Technology of 2 day

Broadband Network

2012-02-14T06:31:00.000-08:00

Broadband Network

In general, broadband refers to telecommunication in which a wide band of frequencies is available to transmit information. Because a wide band of frequencies is available, information can be multiplexed and sent on many different frequencies or channels within the band concurrently, allowing more information to be transmitted in a given amount of time (much as more lanes on a highway allow more cars to travel on it at the same time). Related terms are wideband (a synonym), baseband (a one-channel band), and narrowband (sometimes meaning just wide enough to carry voice, or simply "not broadband," and sometimes meaning specifically between 50 cps and 64 Kpbs).

Various definers of broadband have assigned a minimum data rate to the term. Here are a few:
• Newton's Telecom Dictionary: "...greater than a voice grade line of 3 KHz...some say [it should be at least] 20 KHz."
• Jupiter Communications: at least 256 Kbps.
• IBM Dictionary of Computing: A broadband channel is "6 MHz wide."
It is generally agreed that Digital Subscriber Line (DSL) and cable TV are broadband services in the downstream direction.

Broadband Traffic

Types of traffic carried by the network

Modern networks have to carry integrated traffic consisting of voice, video and data. The Broadband Integrated Services Digital Network (B-ISDN) satisfies these needs . The types of traffic supported by a broadband network can be classified according to three characteristics
• Bandwidth is the amount of network capacity required to support a connection.
• Latency is the amount of delay associated with a connection. Requesting low latency in the Quality of Service (QoS) profile means that the cells need to travel quickly from one point in the network to another.
• Cell-delay variation (CDV) is the range of delays experienced by each group of associated cells. Low cell-delay variation means a group of cells must travel through the network without getting too far apart from one another.

Modern communication services

Society is becoming more informationally and visually oriented. Personal computing facilitates easy access, manipulation, storage, and exchange of information, and these processes require reliable data transmission. The means or media for communicating data are becoming more diverse. Communicating documents by images and the use of high-resolution graphics terminals provide a more natural and informative mode of human interaction than do voice and data alone. Video teleconferencing enhances group interaction at a distance. High-definition entertainment video improves the quality of pictures, but requires much higher transmission rates.
These new data transmission requirements may require new transmission means other than the present overcrowded radio spectrum . A modern telecommunications network (such as the broadband network) must provide all these different services (multi-services) to the user.
Differences between traditional (telephony) and modern communication services
Conventional telephony communicates using:
• the voice medium only,
• connects only two telephones per call, and
• uses circuits of fixed bit-rates.
In contrast, modern communication services depart from the conventional telephony service in these three essential aspects. Modern communication services can be:
• multi-media,
• multi-point, and
• multi-rate.
These aspects are examined individually in the following three sub-sections
Multi-media
A multi-media call may communicate audio, data, still images, or full-motion video, or any combination of these media. Each medium has different demands for communication quality, such as:
• bandwidth requirement,
• signal latency within the network, and
• signal fidelity upon delivery by the network.
The information content of each medium may affect the information generated by other media. For example, voice could be transcribed into data via voice recognition, and data commands may control the way voice and video are presented. These interactions most often occur at the communication terminals, but may also occur within the network .
Multi-point
A few examples will be used to contrast point-to-point communications with multi-point communications. Traditional voice calls are predominantly two party calls, requiring a point-to-point connection using only the voice medium. To access pictorial information in a remote database would require a point-to-point connection that sends low bit-rate queries to the database and high bit-rate video from the database. Entertainment video applications are largely point-to-multi-point connections, requiring one-way communication of full motion video and audio from the program source to the viewers. Video teleconferencing involves connections among many parties, communicating voice, video, as well as data. Offering future services thus requires flexible management of the connection and media requests of a multi-point, multi-media communication call [3][4].
Multi-rate
A multi-rate service network is one which flexibly allocates transmission capacity to connections. A multi-media network has to support a broad range of bit-rates demanded by connections, not only because there are many communication media, but also because a communication medium may be encoded by algorithms with different bit-rates. For example, audio signals can be encoded with bit-rates ranging from less than 1 kbit/s to hundreds of kbit/s, using different encoding algorithms with a wide range of complexity and quality of audio reproduction. Similarly, full motion video signals may be encoded with bit-rates ranging from less than 1 Mbit/s to hundreds of Mbit/s. Thus a network transporting both video and audio signals may have to integrate traffic with a very broad range of bit-rates

Wireless Broadband Networks
What is a Wireless Broadband Network?
Wireless broadband terminology should not be confused with the generic term “broadband networking” or BISDN (Broadband Integrated Services Digital Network), which refers to various network technologies (fiber or optical) implemented by ISPs and NSPs to achieve transmission speeds higher than 155 Mbps for the Internet backbone. In a lay-person’s terms, BISDN is the wire and cable that run through walls, under floors, from pole to telephone pole, and beneath feet on a city street. BISDN is a concept and a set of services and developing standards for integrating digital transmission services in a broadband network of fiber optic and radio media. BISDN encompasses frame relay service for high-speed data that can be sent in large bursts, the Fiber Distributed-Data Interface (FDDI), and the Synchronous Optical Network (SONET). BISDN supports transmission from 2 Mbps to much higher transfer rates.
Wireless broadband, on the other hand, refers to the wireless network technology that addresses the “last mile” problem whereby we can connect isolated customer premises to an ISP or carrier’s backbone network without leasing traditional T-1 and higher speed copper or fiber channels from your local telecommunication service provider. Wireless broadband refers to fixed wireless connectivity that can be utilized by enterprises, businesses, households and telecommuters who travel from one fixed location to another fixed location. In its current implementation, it does not address the needs of “mobile users” on the road.

Technologically, wireless broadband is an extension of the point-to-point, wireless-LAN bridging concept to deliver high-speed and high capacity pipe that can be used for voice, multi-media and Internet access services. While in simple implementations, primary use of wireless broadband is for connecting LANs to the Internet, in more sophisticated implementations, you may connect multiple services (data, voice, video) over the same pipe. The latter requires multiplexing equipment at customer premises or in a central hub.
From an implementation perspective Wireless Broadband circumvents physical telecommunications networks; it is as feasible in rural as it is in urban areas. For topographies that haven’t yet technically evolved to cable and copper wire infrastructures, vendor solutions circumventing costly installation, maintenance and upgrades, means skipping 120 years of telecommunications evolution. In other areas, deregulation is making the licensing process for Wireless Service Providers (WSPs) hassle free.
Wireless broadband is faster to market, and subscribers are added incrementally, bypassing those installations that are required before wired subscribers can connect.
What Wireless Broadband is Not?
Wireless broadband is for fixed wireless connection - it does not address the mobility needs which at present only 2.5 G and 3G networks intend to provide. In future, there is a technical possibility that broadband wireless radios can be miniaturized and installed in handheld devices. Then they might be able to augment 3G in mobile applications However, it is only a possibility of the physics and electronics - none of the vendors have any prototype products in this area. Of course, wireless broadband is expected to meet the needs of residential connections to the Internet bypassing local telcos.
Four technologies for faster broadband in 2011
10G GPON

The use of PON (passive optical network) technology in fixed broadband networks has grown in popularity in the last couple of years, thanks to lower costs compared to using an optical fiber for each household. The technology calls for several households to share the same capacity, which is sent over a single optical fiber.
Today's systems have an aggregate download capacity of 2.5G bps (bits per second). The move to 10G GPON increases that by a factor of four, hence the name. The technology is also capable of an upstream capacity of 10G bps, which is eight times faster than current networks, according to Verizon Communications.
The increased capacity can either be used to handle more users or increase the bandwidth.
In December 2009, Verizon announced that it had conducted the first field-test for the technology. Since then, a number of operators have conducted tests, including France Telecom, Telecom Italia, Telefonica, Portugal Telecom, China Mobile and China Unicom, according to Huawei.
The first commercial services based on 10G GPON are expected in the second half 2011, according to Alcatel-Lucent. Pioneering operator Verizon hasn't announced any commercial plans yet, according to a spokesman.
Besides broadband, the technology is also being pitched for mobile backhaul use.

VDSL2
The DSL family of technologies still dominates the fixed broadband world. To ensure that operators can continue to use their copper networks, network equipment vendors are adding some new technologies to VDSL2 to increase download speeds to several hundred megabits per second
To boost DSL to those kinds of speeds, the vendors are using a number of technologies. One way is to send traffic over several copper pairs at the same time, compared to traditional DSL, which only uses one copper pair. This method then uses a technology -- called DSL Phantom Mode by Alcatel-Lucent and Phantom DSL by Nokia Siemens -- that can create a third virtual copper pair that sends data over a combination of two physical pairs.
However, the use of these technologies also creates crosstalk, a form of noise that degrades signal quality and decreases bandwidth. To counteract that, vendors are using a noise-canceling technology called vectoring. It works the same way as noise-canceling headphones, continuously analyzing the noise conditions on the copper cables, and then creates a new signal to cancel it out, according to Alcatel-Lucent.
Products are now entering field trials and the first commercial services are expected to be launched in 2011. Just like 10G GPON, it is also being pitched as an alternative for mobile backhaul.
LTE

The rollout of LTE (Long Term Evolution) is now under way in Europe, Asia and the U.S., and by the end of 2011 about 50 LTE commercial networks will have launched, according to an October report from the Global Mobile Suppliers Association (GSA) detailing current operator launch plans.

The first round of LTE services, with the exception of MetroPCS and its Samsung Craft phone, connects users with USB modems. That will change in 2011 with the arrival of LTE capable smartphones and tablets. Verizon Wireless expects such handsets will be available by mid-2011, according to a statement.

The bandwidth and coverage operators can offer depends on their spectrum holdings.

LTE isn't just about offering higher speeds to metropolitan areas. In Germany, the government has mandated that the mobile operators first use the technology to offer broadband to rural areas.

Besides higher speeds LTE also offers lower latencies, which will help the performance of real-time applications sensitive to delays, including VoIP (Voice over Internet Protocol) video streaming, video conferencing and gaming, to perform better.

The rollout of isn't going to happen overnight, even for those operators that have are now launching services. By 2013, Verizon plans to cover its entire 3G network with LTE. Telenor in Sweden also plans to have its network upgrade complete by 2013, according to a statement.
HSPA+

LTE may be getting most of the attention, but 2010 has been a banner year for HSPA+ (High-Speed Packet Access). Migration to HSPA+ has been a major trend this year and more than one in five HSPA operators have commercially launched HSPA+ networks, according to the GSA.

However, today's download speeds of up to 21Mbps is far from the end of the line for HSPA+. Nine operators -- including Bell Mobility in Canada and Telstra in Australia -- have already launched services at 42Mbps. The average real-world download speed is 7Mbps to 14Mbps, according to Bell.

To get to that speed, operators use a technology called DC-HSPA+ (Dual-Channel High-Speed Packet Access), which sends data using two channels at the same time.

More than 30 DC-HSPA+ (42Mbps) network deployments are on-going or committed to, including T-Mobile in the U.S. It will launch services next year, but isn't ready give any additional details on timing, according to a spokeswoman.

Also, five operators have already committed to 84Mbps, which is the next evolution step for their HSPA+ networks, the first of which is also expected to arrive next year.
IP Broadband Network Management Ericsson's

Ericsson's IP Broadband Network Management portfolio is a cutting-edge network management system solution for IP and broadband networks that contributes to improved service delivery and performance while lowering costs. It includes Ericsson IP Transport NMS, ServiceOn family and NetOp EMS.
Managing the Broadband Revolution
IP Broadband Network Management portfolio manages the complete range of technologies used for the deployment of Ericsson broadband network systems. Managed components include copper, fiber and radio-based transmission systems for both narrowband and broadband data. Managed transport technologies include IP, MPLS-TP, MPLS, Ethernet, PDH, SDH, ODU, ATM, DWDM, CWDM and xDSL.

Multi-layer management
Service, network and element management layers can be seamlessly integrated into a single solution, based on a selection of integrated products from the IP Broadband Network Management portfolio. Key features include administration of customers and services, facilities management, routing of network trails, network map presentation with fault and performance monitoring, equipment and inventory management.

Distributed, scalable and resilient architecture
IP Broadband Network Management can be tailored to the operator's requirements according to functional, organizational, security or geographical criteria. The solution is scalable and can easily grow with the managed network.

Open interfaces for integration
IP Broadband Network Management includes an open integration framework enabling it to serve as a higher-order management system for subordinate managers or network elements. The integration framework supports a number of network management protocols including SNMP, CLI, XML and Corba. A range of strategic 3rd party network element integrations are already supported as ready-to-manage solutions.
IP Broadband Network Management supports the international TeleManagement Forum (TMF) standard to facilitate platform-independent access to system resources from a variety of distributed client applications. This architecture is used to realize a range of northbound and external interfaces including a web-based customer care management application.

Field-proven expertise
Ericsson's IP Broadband Network Management portfolio has been developed using Ericsson field proven worldwide expertise in telecom networks, delivering cost savings to the operators and new capabilities to the IP Broadband network portfolio. The solution exploits completely the characteristics of each network technology, delivers advance functionality like traffic restoration or alarm correlation, and support operators' way of working and procedures.

User-friendly operation
With IP Broadband Network Management the emphasis is on user-friendliness and consistency of presentation to increase operator efficiency and effectiveness, also to minimize training overheads. Network Management is performed by a graphical user interface specially designed to leverage the commonality between different technologies and tasks. The user can move between managed technologies and management layers with ease.

As the IP Broadband Network Management portfolio is inherently modular it is possible to deliver the following levels of network management for all the broadband networks elements:
• Element management solutions, providing centralized, feature-rich maintenance support platform
• Network management solutions, allowing end-to-end provisioning, fault and performance analysis across the entire domain of broadband networks
• Cross-domain management solutions, supporting multi-technology and multi-vendor networks
• Integration capabilities, providing seamless and easy integration of IP Broadband Network Management with customers' existing systems
• Service management solutions, delivering integrated service management across multiple domains
IP Broadband Network Managementfor broadband networks is also open to adaptation and customization to serve any special needs of operators worldwide.
• Over 650 customers worldwide
• Covering all broadband network technologies, including optical and microwave transport and broadband access
• Carrier class, Tier-1 approved with High Availability options
• Scalable to meet Tier 1, Tier 2, new operators and private network requirements
• Unique management features
• Integrated with Ericsson OSS's

Public Safety Broadband Network

Objective
To develop communications and network models for public safety broadband networks, and to analyze and optimize the performance of these networks.
Background
The FCC and the Administration have called for the deployment of a nationwide, interoperable public safety mobile broadband network. Public safety has been allocated broadband spectrum in the 700 MHz band for such a network. The National Public-Safety Telecommunications Council and the FCC have endorsed the 3GPP Long Term Evolution (LTE) standard as the technology of choice for this network.
Network Analysis and Optimization
The Emerging & Mobile Network Technologies Group (EMNTG) performs RF network analysis and optimization of public safety broadband networks using commercially available and in-house customized network modeling and simulation tools. Current efforts are focused on wide area networks based on LTE techology.
Network analyses can be used to predict wide area performance metrics over a defined geographic area, such as the uplink and downlink:
• Signal-to-interference-and-noise ratio,
• Coverage probability, and
• Achievable data rate.

The tools can also be used to optimize network configurations (e.g., sector antenna directions, transmission powers) for various optimization criteria (e.g., maximum coverage area).

Protocol Modeling and Simulation

EMNTG also develops and customizes protocol-level models of wireless technologies such as LTE. These models can be used to perform more detailed simulations of an incident area communication scenario. They include models of the application traffic (e.g., push-to-talk voice, video streams, file transfers), lower layer communication protocols, and the RF channel environment. Performance metrics generated by these models include
• Achieved throughput
• Communication delay
• Packet loss rate
• Network utilization

Protocol models complement the wide area network analysis and optimization tools described above to provide a more complete picture of the expected public safety communication performance. Using the cell sizes, antenna configurations, and transmission powers obtained from a network optimization, the protocol-level analysis generates realistic sector loads which can be fed back to the network analysis and optimization tools for further refinement of the optimized configuration.

Channel Measurements
The fidelity of the predictions generated by the network and protocol models is dependent in large part on the accuracy of the underlying RF channel propagation model. In collaboration with its partners in NIST/PML, EMNTG collects and analyzes channel measurements that are used to develop and tune RF propagation models. Of particular relevance to the Public Safety Broadband Network, these efforts include measurements in the 700 MHz public safety band.

Multiservice broadband network technology

Multiservice broadband networks are on the verge of becoming a reality. The key drivers are rapid advances in technologies; privatization and competition; the convergence of the telecommunication, data communication, entertainment, and publishing industries; and changes in consumers' life-styles.
Wide-area networks today consist of separate networks for voice, private lines, and data services, supported by a common facility infrastructure. Similar separation between voice and data networks exists on enterprise premises (Fig. 1). Residential users typically use copper loop to access voice networks as well as data networks (using voice-band modems).

Fig. 1 Current network architecture.

Public voice and private line networks have been designed for very low latency and with an unrelenting attention to reliability and quality of service. Data networks (especially the public Internet) introduce longer and less predictable delays and are not suitable for highly interactive communication. For the most part, the Internet has not yet been shown to be reliable enough for mission-critical functions.
The time is ripe for these networks to change in fundamental ways. There is a demand for services involving multiple media, increasing intelligence, diverse speeds, and varied quality-of-service requirements. Increasing dependence on network services requires all forms of networking to be as reliable as today's voice network. The revolution taking place in electronics and photonics will provide ample opportunities to satisfy these requirements.
Technological advances
The storage capacity of a single dynamic read-only-memory (DRAM) chip increased from 64 kilobits in 1970 to 256 megabits in 1998, and 4-gigabit chips are possible in research laboratories (Fig. 2 a). Development of multistate transistors and new lithographic techniques (enabling the fabrication of atomic-scale transistors) promise the continuation of this trend. The computing power in a single microprocessor chip increased from 1 million instructions per second (MIPS) in 1981 to about 400 MIPS in 1998, and no limit is in sight (Fig. 2 b). These advances are being translated into explosive growth in switching and routing capacities, information processing capacities, database sizes, and data retrieval speeds. Atomic-scale transistors also promise “system on a chip,” resulting in inexpensive wearable computers, smart appliances, and wireless devices. They also promise less power consumption and longer battery life.

Fig. 2 Progress in semiconductor technologies. (a) Density of dynamic random-access memories (DRAMs). Lengths (in micrometers) are minimum internal spacings of chip components. Advances in manufacturing techniques allow narrower spacing, making
possible higher density and hence larger storage capacity. (b) Microprocessor speeds.
The advances in photonics are even more remarkable. The capacity of a single optical fiber increased from 45 megabits per second in 1981 to 1.7 gigabits per second in 1990 (Fig. 3). A major change occurred with the advent of dense wavelength-division multiplexing (DWDM) and optical amplifiers. Dense wavelength-division multiplexing allows the transport of many colors (wavelengths) of light in one fiber, while optical amplifiers amplify all wavelengths in a fiber simultaneously. These two innovations have made it possible to carry 400 gigabits per second (40 wavelengths each carrying 10 gigabits per second) on a single fiber and 1600 Gbps systems are on the horizon. Experimental work in research laboratories is pushing this capacity to over 3 terabits per second. Recent innovations have made it possible to put 432 fibers in a single cable. One such cable will be able to transport the daily volume of current worldwide traffic in 60 seconds. Many new and existing operators of wide-area networks have already started capitalizing on this growth in transport capacity. Transport capacity in wide-area networks around the world is expected to increase by a factor of up to 1000 by 2005.

Fig. 3 Capacity growth in long-haul optical fibers. Evolution is plotted in both the total capacity and the number of wavelengths employed.
Advances in electronics and photonics will also permit tremendous increases in access speeds, releasing the residential and small business users from the current speed restriction of the “last mile” on the copper loop that links the user to the network. New digital subscriber loop (DSL) technologies use advanced coding and modulation techniques to carry from several hundred kilobits per second to 50 megabits per second on the copper loop. Hybrid fiber-coaxial (HFC) technologies allow the use of cable television channels to provide several megabits per second upstream and up to 40 megabits per second downstream for a group of about 500 homes. Similar access speeds may also be provided by hybrid fiber-wireless technologies. Fiber-to-the-curb (FTTC) and fiber-to-the-home (FTTH) technologies provide up to gigabits per second to single homes by bringing fiber closer to the end users. Passive optical networks (PONs) will allow a single fiber from the central hub to serve several hundred homes by providing one or more wavelengths to each home using wavelength splitting techniques.
Advances in network infrastructure
Innovations in software technologies, network architectures, and protocols will harness this increase in networking capacities to realize true multiservice networks.
Narrowband voice [analog, ISDN (Integrated Services Digital Network), and cellular] and Internet Protocol (IP)–based data end systems are likely to continue operating well into the future, as are the Ethernet-based local-area networks. Most of the present growth is in IP-based end systems and cellular telephones, although many parts of the world are still experiencing enormous growth in analog and ISDN telephones. New services are being developed for the IP-based end systems (such as multimedia collaboration, multimedia call centers, distance learning, networked home appliances, directory assisted networking, on-line language translation, and telemedicine). These services will coexist with the traditional voice and data services. See also: Distance education

One challenge is to find the right network architecture for transporting efficiently the traffic generated by current and new services. An approach involving selective layered bandwidth management (SLBM) provides efficiency, robustness, and evolvability. SLBM uses all or some of the IP, Asynchronous Transfer Mode (ATM), SONET/SDH (synchronized optical network/synchronized digital hierarchy), and optical networking layers, depending on the traffic mix and volume (Fig. 4).

Fig. 4 Protocol layering and evolution. Heavy arrows represent new and future layering. PPP is Point-to-Point protocol; HDLC, High-speed Data-Link Control (used here only for

Fig. 4 Protocol layering and evolution. Heavy arrows represent new and future layering. PPP is Point-to-Point protocol; HDLC, High-speed Data-Link Control (used here only for the purpose of delineating the packets); SDL, Simplified Data-Link protocol; HSSF, High-Speed Synchronous Framing protocol; Cell PL, (ATM) Cell-based Physical Layer.

For the near future, ATM provides the best technology for a true multiservice backbone due to its extensive quality-of-service and traffic management features such as admission controls, traffic policing, service scheduling, and buffer management. An ATM backbone network can support the traditional voice traffic, new packet voice traffic, various types of video traffic, Eithernet traffic, and IP traffic. The ATM Adaptation Layer protocols AAL1, AAL2, and AAL5 facilitate this integration. ATM also enables creation of link-layer (layer 2) virtual private networks (VPNs) over a shared public network infrastructure while providing secure communication and performance guarantees.
Traditional voice, IP, and ATM traffic will be transported over the circuits provided by the SONET/SDH network layer over the optical (wavelength) layer. SONET/SDH networks allow partitioning of the wavelength capacity into lower-granularity circuits which can be used by this traffic for efficient networking. The SONET/SDH layer also provides extensive performance monitoring. Finally, SONET/SDH networks, formed using ring topology, allow simple and fast (several tens of milliseconds) rerouting around a failure in a link or a node. This fast restoration of service makes such failures transparent to the service layers. The optical layer will consist of point-to-point fiber links over which many wavelengths will be multiplexed to allow very efficient use of the fiber capacity. Many public carriers and enterprise networks will use this multilayered networking. However, all these situations will change over time.
Rapid growth of IP end systems and high access speeds to the wide-area networks will create high point-to-point IP demands in the core backbone. At this level of traffic, the finer bandwidth partitioning provided by the ATM layer may not compensate for the additional protocol and equipment overhead. Thus, an increasingly higher portion of IP traffic will be carried directly over SONET/SDH circuits. At even higher traffic levels, even the partitioning provided by the SONET/SDH layer will be unnecessary. Meanwhile, optical cross connects and add-drop multiplexers will allow true optical-layer networking using ring or mesh topology. New techniques and algorithms being developed for very fast restoration at the optical layer will further reduce the need for the SONET/SDH layer. IP-over-wavelength networking is then expected to develop.
Of course, this simplification in the network infrastructure requires IP- and Ethernet-based networks to multiplex voice, data, video, and multimedia services directly over the SONET/SDH or dense wavelength-division multiplexing layer. Ethernet and IP protocols are being enhanced to allow such multiplexing.
New high-capacity local-area network switches (layer 2/3 switches) provide fast (10–1000 megabits per second) interfaces and large switching capacities. They also eliminate the need for contention-based access over shared-media local-area networks. Protocol standards (802.1p and 802.1q) are being defined to provide multiple classes of service over such switches by providing different delay and loss controls. Similarly, router technology and Internet protocols are beginning to eliminate the bottlenecks caused by software-based forwarding, rigid routing, and undifferentiated packet processing. New IP switches (layer 3 switches) use hardware-based packet forwarding in each input port, permitting very high capacities (60–1000 gigabits per second, or 50–1000 million packets per second). Protocols are being defined to use the Differential Service (DS) field in the header of each IP packet to signal the quality-of-service requirement of the application being supported by that packet. Intelligent buffering and packet scheduling algorithms in IP switches can use this field to provide differential quality of service as measured by delay, jitter, and losses. At the interface between layer 2 and layer 3 switches, conversion between 802.1p- and DS-based signaling can provide seamless quality-of-service management within enterprise and carrier networks. Resource reservation protocols are being defined to allow the application of signal resource requirements to the network. Traffic-policing algorithms will guarantee that the traffic entering the network is consistent with the resources reserved by the reservation protocols. Resource reservation protocols and traffic policing will further help quality-of-service management. Two other factors will add to the quality-of-service capability of IP networks. In particular, hierarchical classification of IP traffic using additional fields in the header will allow bandwidth guarantees and delay control for individual or aggregated flows based on the users as well as applications. Also, ongoing work on Multi Protocol Label Switching (MPLS) will allow flexible routing and traffic engineering in IP networks.
With these capabilities, public carriers can offer IP-layer (layer 3) virtual private networks to many enterprise customers over a shared infrastructure. Carrier-based policy servers, service and resource provisioning servers, and directories will interact with enterprise policy servers to map the enterprise requirements into carrier actions consistent with the overall virtual private network contract.
While backbone networks are likely to become more uniform, many different access technologies (such as copper loop, wireless, fiber, coaxial cable, fiber-cable hybrid, and satellite) will continue to play major roles in future networks. Standards are being defined for each of the access technologies to support diverse quality-of-service requirements over one interface. Thus, a true end-to-end solution is expected for multiservice broadband networking.
See also: Data communications; Integrated circuits; Integrated services digital network (ISDN); Local-area networks; Microprocessor; Optical communications; Packet switching; Semiconductor memories; Telephone service; Wide-area networks

New technology uses human body for broadband networking
Your body could soon be the backbone of a broadband personal data network linking your mobile phone or MP3 player to a cordless headset, your digital camera to a PC or printer, and all the gadgets you carry around to each other.
These personal area networks are already possible using radio-based technologies, such as Wi-Fi or Bluetooth, or just plain old cables to connect devices. But NTT, the Japanese communications company, has developed a technology called RedTacton, which it claims can send data over the surface of the skin at speeds of up to 2Mbps -- equivalent to a fast broadband data connection.
Using RedTacton-enabled devices, music from an MP3 player in your pocket would pass through your clothing and shoot over your body to headphones in your ears. Instead of fiddling around with a cable to connect your digital camera to your computer, you could transfer pictures just by touching the PC while the camera is around your neck. And since data can pass from one body to another, you could also exchange electronic business cards by shaking hands, trade music files by dancing cheek to cheek, or swap phone numbers just by kissing.
NTT is not the first company to use the human body as a conduit for data: IBM pioneered the field in 1996 with a system that could transfer small amounts of data at very low speeds, and last June, Microsoft was granted a patent for "a method and apparatus for transmitting power and data using the human body."
But RedTacton is arguably the first practical system because, unlike IBM's or Microsoft's, it doesn't need transmitters to be in direct contact with the skin -- they can be built into gadgets, carried in pockets or bags, and will work within about 20cm of your body. RedTacton doesn't introduce an electric current into the body -- instead, it makes use of the minute electric field that occurs naturally on the surface of every human body. A transmitter attached to a device, such as an MP3 player, uses this field to send data by modulating the field minutely in the same way that a radio carrier wave is modulated to carry information.
Receiving data is more complicated because the strength of the electric field involved is so low. RedTacton gets around this using a technique called electric field photonics: A laser is passed though an electro-optic crystal, which deflects light differently according to the strength of the field across it. These deflections are measured and converted back into electrical signals to retrieve the transmitted data.
An obvious question, however, is why anyone would bother networking though their body when proven radio-based personal area networking technologies, such as Bluetooth, already exist? Tom Zimmerman, the inventor of the original IBM system, says body-based networking is more secure than broadcast systems, such as Bluetooth, which have a range of about 10m.
"With Bluetooth, it is difficult to rein in the signal and restrict it to the device you are trying to connect to," says Zimmerman. "You usually want to communicate with one particular thing, but in a busy place there could be hundreds of Bluetooth devices within range."
As human beings are ineffective aerials, it is very hard to pick up stray electronic signals radiating from the body, he says. "This is good for security because even if you encrypt data it is still possible that it could be decoded, but if you can't pick it up it can't be cracked."
Zimmerman also believes that, unlike infrared or Bluetooth phones and PDAs, which enable people to "beam" electronic business cards across a room without ever formally meeting, body-based networking allows for more natural interchanges of information between humans.
"If you are very close or touching someone, you are either in a busy subway train, or you are being intimate with them, or you want to communicate," he says. "I think it is good to be close to someone when you are exchanging information."

RedTacton transceivers can be treated as standard network devices, so software running over Ethernet or other TCP/IP protocol-based networks will run unmodified.
Gordon Bell, a senior researcher at Microsoft's Bay Area Research Center in San Francisco, says that while Bluetooth or other radio technologies may be perfectly suitable to link gadgets for many personal area networking purposes, there are certain applications for which RedTacton technology would be ideal.
"I recently acquired my own in-body device -- a pacemaker -- but it takes a special radio frequency connector to interface to it. As more and more implants go into bodies, the need for a good Internet Protocol connection increases," he says.
In the near future, the most important application for body-based networking may well be for communications within, rather than on the surface of, or outside, the body.
An intriguing possibility is that the technology will be used as a sort of secondary nervous system to link large numbers of tiny implanted components placed beneath the skin to create powerful onboard -- or in-body -- computers.

References

http://www.mobileinfo.com

http://www.infoworld.com

http://www.ericsson.com

http://www.nist.gov

http://accessscience.com

http://searchtelecom.techtarget.com

http://en.wikipedia.org

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How Does A Refrigerator Work?

2012-02-11T22:30:00.000-08:00

How Does A Refrigerator Work?

Now here's a cool idea: a metal box that helps your food last longer! Have you ever stopped to think how a refrigerator keeps cool, calm, and collected even in the blistering heat of summer? Food goes bad because bacteria breed inside it. But bacteria grow less quickly at lower temperatures, so the cooler you can keep food, the longer it will last. A refrigerator is a machine that keeps food cool with some very clever science. All the time your refrigerator is humming away, liquids are turning into gases, water is turning into ice, and your food is staying deliciously fresh. Let's take a closer look at how a refrigerator works!

How to move something you can't even see
Suppose your chore for today is to empty a stable full of rank smelling horse manure. Not the nicest of jobs, so you'll want to do it as quickly as possible. You won't be able to move it all at once, because there's too much of it. To get the job done fast, you need to move as much manure as you can in one go. The best thing to do is use a wheelbarrow. Pile the manure up into the barrow, wheel the barrow outside, and then empty the manure into a pile in the stable yard. With a few of these trips, you can shift the manure from inside the stable to outside.
Moving something you can see is easy. But now let's give you a harder chore. Your new task is to move the heat from the inside of a refrigerator to the outside to keep your food fresh. How can you move something you can't see? You can't use a wheelbarrow this time. Not only that, but you can't open the door to get at the heat inside, or you'll let the heat straight back in again. Your mission is to remove the heat, continually, without opening the door even once. Tricky problem, eh? But it's not impossible—at least not if you understand the science of gases

How to move heat with a gas
Let's step sideways a moment and look at how gases behave. If you've ever pumped up the tires on a bicycle, you'll know that a bicycle pump soon gets quite warm. The reason is that gases heat up when you compress (squeeze) them. To make the tire support the weight of the bicycle and your body, you have to squeeze air into it at a high pressure. Pumping makes the air (and the pump it passes through) a little bit hotter. Why? As you squeeze the air, you have to work quite hard with the pump. The energy you use in pumping is converted into potential energy in the compressed gas: the gas in the tire is at a higher pressure and higher temperature than the cool air around you. If you squeeze a gas into half the volume, the heat energy its molecules contain fills only half as much space, so the temperature of the gas rises (it gets hotter).
What happens if you release a gas that's stored at high pressure? When you spray an aerosol air freshener, you've probably noticed that the spray is really cold—for exactly the opposite reason that a bicycle pump gets hot. When you release the gas, it is suddenly able to expand and occupy much more volume. The heat energy its molecules contain is now divided over a much bigger volume of space, so the temperature of the gas falls (it gets cooler).

The heating and cooling cycle
By compressing gases, we make them hotter; by letting them expand, we make them cooler. How can we use this handy bit of physics to shift heat from the inside of a refrigerator? Suppose we made a pipe that was partly inside a refrigerator and partly outside it, and sealed so it was a continuous loop. And suppose we filled the pipe with a gas. Inside the refrigerator, we could make the pipe gradually get wider, so the gas would expand and cool as it flowed through it. Outside the refrigerator, we could have something like a bicycle pump to compress the gas and release its heat. If the gas flowed round and round the loop, expanding when it was inside the refrigerator and compressing when it was outside, it would constantly pick up heat from the inside and carry it to the outside like a heat conveyor belt.

And, surprise surprise, this is almost exactly how a refrigerator works. There are some extra details worth noting. Inside the refrigerator, the pipe expands through a nozzle known as an expansion valve. As the gas passes through it, it cools dramatically. This bit of science is sometimes known as the Joule-Thomson (or Joule-Kelvin) effect for the physicists who discovered it, James Prescott Joule (1818–1889) and William Thomson (Lord Kelvin, 1824–1907). You won't be surprised to discover that the compressor outside the refrigerator is not really a bicycle pump! It's actually an electrically powered pump. It's the thing that makes a refrigerator hum every so often. The compressor is attached to a grill-like device called a condenser (a kind of thin radiator behind the refrigerator) that expels the unwanted heat. Finally, the gas that circulates round the pipe is actually a specially designed chemical that alternates between being a cool liquid and a hot gas. This chemical is known as the coolant or refrigerant.

Here's what's happening inside your refrigerator as we speak! The left-hand picture shows what's happening on the inside back wall of the chiller cabinet. The right-hand picture shows what's going around the back of the fridge on the outside.
1. The coolant is a liquid as it enters the expansion valve. As it passes through, the sudden drop in pressure makes it expand, cool, and turn into a gas (just like a liquid aerosol turns into a cool gas when you spray it out of a can).
2. As the coolant flows around the chiller cabinet (usually around a pipe buried in the back wall), it absorbs and removes heat from the food inside.
3. The compressor squeezes the coolant, raising its temperature and pressure. It's now a hot, high-pressure gas.
4. The coolant flows through thin pipes on the back of the fridge, giving out its heat and cooling back into a liquid as it does so.
5. The coolant flows back into the expansion valve and the cycle repeats itself. So heat is constantly picked up from inside the refrigerator and put down again outside it.

Norcold refrigerator circuit board replacement

LG Refrigerator Circuit diagram Parts

Old Refrigerators
If you look at the back or bottom of an older refrigerator, you'll see a long thin tube that loops back and forth. This tube is connected to a pump, which is powered by an electric motor.
Inside the tube is Freon, a type of gas. Freon is the brand name of the gas. This gas, chemically is called Chloro-Flouro-Carbon or CFC. This gas was found to hurt the environment if it leaks from refrigerators. So now, other chemicals are used in a slightly different process (see next section below).
CFC starts out as a liquid. The pump pushes the CFC through a lot of coils in the freezer area. There the chemical turns to a vapor. When it does, it soaks up some of the heat that may be in the freezer compartment. As it does this, the coils get colder and the freezer begins to get colder.
In the regular part of your refrigerator, there are fewer coils and a larger space. So, less heat is soaked up by the coils and the CFC vapor.
The pump then sucks the CFC as a vapor and forces it through thinner pipes which are on the outside of the refrigerator. By compressing it, the CFC turns back into a liquid and heat is given off and is absorbed by the air around it. That's why it might be a little warmer behind or under your refrigerator.
Once the CFC passes through the outside coils, the liquid is ready to go back through the freezer and refrigerator over and over.

Today's Refrigerators
Modern refrigerators don't use CFC because CFCs are harmful to the atmosphere if released. Instead they use another type of gas called HFC-134a, also called tetrafluoroethane. HFC turns into a liquid when it is cooled to -15.9 degrees Fahrenheit (-26.6 degrees Celsius).
A motor and compressor squeezes the HFC. When it is compressed, a gas heats up as it is pressurized. When you pass the compressed gas through the coils on the back or bottom of a modern refrigerator, the warmer gas can lose its heat to the air in the room.
Remember the law of thermodynamics.
As it cools, the HFC can change into a liquid because it is under a high pressure.
The liquid flows through what's called an expansion valve, a tiny small hole that the liquid has to squeeze through. Between the valve and the compressor, there is a low-pressure area because the compressor is pulling the ammonia gas out of that side.
When the liquid HFC hits a low pressure area it boils and changes into a gas. This is called vaporizing.
The coils then go through the freezer and regular part of the refrigerator where the colder liquid in the coil pulls the heat out of the compartments. This makes the inside of the freezer and entire refrigerator cold.
The compressor sucks up the cold gas, and the gas goes back through the same process over and over.

How Does the Temperature Stay the Same Inside?
A device called a thermocouple (it's basically a thermometer) can sense when the temperature in the refrigerator is as cold as you want it to be. When it reaches that temperature, the device shuts off the electricity to the compressor.
But the refrigerator is not completely sealed. There are places, like around the doors and where the pipes go through, that can leak a little bit.
So when the cold from inside the refrigerator starts to leak out and the heat leaks in, the thermocouple turns the compressor back on to cool the refrigerator off again.
That's why you'll hear your refrigerator compressor motor coming on, running for a little while and then turning itself off.
Today's refrigerators, however, are very energy efficient. Ones sold today use about one-tenth the amount of electricity of ones that were built 20 years ago. So, if you have an old, old refrigerator, it's better to buy a new one because you'll save money (and energy) over a long period of time.

For more information go to:
• Argone National Laboratory - Ask A Scientist (http://newton.dep.anl.gov/newton/askasci/1993/eng/ENG30.HTM)

• Mr. Hand's 8th Grade Science Site (www.mansfieldct.org/schools/mms/staff/hand/heatrefrig.htm)

• How Stuff Works - Refrigerator (www.howstuffworks.com/refrigerator.htm)

• Science Treasure Trove - refrigerator page (www.education.eth.net/acads/treasure_trove/refrigerator.htm)

Reference

1.www.explainthatstuff.com
2.www.energyquest.ca.gov

INTRODUCTION TO MICROCONTROLLERS

2011-09-27T04:15:00.000-07:00

INTRODUCTION TO MICROCONTROLLERS

What are micro controllers? They are what their name suggests. Today they can be found in almost any complex electronic device - from portable music devices to washing machines to your car. They are programmable, cheap, small, can handle abuse, require almost zero power, and there are so many variaties to suit every need. This is what makes them so useful for robotics - they are like tiny affordable computers that you can put right onto your robot.

Augmented Microcontrollers and Development Boards

In a pure sense, a micro controller is just an IC (integrated circuit, or a black chip thing with pins coming out of it). However it is very common to add additional external components, such as a voltage regulator, capacitors, LEDs, motor driver, timing crystals, rs232, etc to the basic IC. Formally, this is called an augmented microcontroller. But in reality, most people just say 'microcontroller' even if it has augmentation. Other abbreviations would be ucontroller and MicroController Unit (MCU). Usually when I say 'microcontroller' what I really mean to say is 'augmented microcontroller.'

As a beginner it is probably best to buy an augmented micro controller. Why? Well because they have tons of goodies built onto them that are all assembled and debugged for you. They also often come with tech support, sample code, and a community of people to help you with them. My micro controller parts list shows the more popular types that you can buy. They tend to cost from $30 to $150 depending on the features. This will give you a good introductory to micro controller programming without having to be concerned with all the technical stuff.

In the long term however you should build your own augmented microcontroller so that you may understand them better. The advantage to making your own is that it will probably cost you from $10-$30.

Between getting a full augmented board and doing it yourself is something called a development board. These boards come pre-augmented with just the bare basics to get you started. They are designed for prototyping and testing of new ideas very quickly. They typically cost between $15 and $40.

What comes with the IC?

There is a huge variety of microcontrollers out on the market, but I will go over a few common features that you will find useful for your robotics project.

For robots, ore important than any other feature on a microcontroller, is the I/O ports. Input ports are used for taking in sensor data, while output is used for sending commands to external hardware such as servos. There are two types of I/O ports, analog and digital.

Analog Input Ports

Analog Ports are necessary to connect sensors to your robot. Also known as an analog to digital converter (ADC), they recieve analog signals and convert them to a digital number within a certain numerical range.

So what is analog? Analog is a continuous voltage range and is typically found with sensors. However computers can only operate in the digital realm with 0's and 1's. So how does a microcontroller convert an analog signal to a digital signal?

First, the analog is measured after a predefined period of time passes. At each time period, the voltage is recorded as a number. This number then defines a signal of 0's and 1's as shown:

The advantage of digital over analog is that digital is much better at eliminating background noise. Cell phones are all digital today, and although the digital signal is less representative than an analog signal, it is much less likely to degrade since computers can restore damaged digital signals. This allows for a clearer output signal to talk to your mom or whoever. MP3's are all digital too, usually encoded at 128 kbps. Higher bit rates obviously mean higher quality because they better represent the analog signal. But higher bit rates also require more memory and processing power.

Most microcontrollers today are 8 bit, meaning they have a range of 256 (2^8=256). There are a few that are 10 bit, 12 bit, and even 32 bit, but as you increase precision you also need a much faster processor.

What does this bit stuff mean for ADC? For example, suppose a sensor reads 0V to an 8 bit ADC. This would give you a digital ouput of 0. 5V would be 255. Now suppose a sensor gave an output of 2.9V, what would the ADC output be?

Doing the math:

2.9V/5V = X/255

X = 2.9*255/5 = 148

So how do you use an analog port? First make sure your sensor output does not exceed your digital logic voltage (usually 0V -> 5V). Then plug that output directly to the analog port.

This bit range could also be seen as a resolution. Higher resolutions mean higher accuracy, but occasionally can mean slower processing and more succeptability to noise. For example, suppose you had a 3 bit controller which has a range of 2^3=8. Then you have a distance sensor that outputed a number 0->7 (a total of 8) that represents the distance between your robot and the wall. If your sensor can see only 8 feet, then you get a resolution of 1 bit per foot (8 resolution / 8 feet = 1). But then suppose you have an 8 bit controller, you would get 256/8=32 ~ 1 bit per centimeter - way more accurate and useful! With the 3 bit controller, you could not tell the difference between 1 inch and 11 inches.

Digital I/O Ports

Digital ports are like analog ports, but with only 1 bit (2^1=2) hence a resolution of 2 - on and off. Digital ports obviously for that reason are rarely used for sensors, except for maybe on/off switches . . . What they are mostly used for is signal output. You can use them to control motors or LED's or just about anything. Send a high 5V signal to turn something on, or a low 0V to turn something off. Or if you want to have an LED at only half brightness, or a motor at half speed, send a square wave. Square waves are like turning something on and off so fast that its almost like sending out an analog voltage of your choice. Neat, huh?

This is an example of a square wave for PWM:

These squarewaves are called PWM, short for pulse width modulation. They are most often used for controlling servos or DC motor H-Bridges.

Also a quick side note, analog ports can be used as digital ports.

Serial Communication, RS232, UART

A serial connection on your microcontroller is very useful for communication. You can use it to program your controller from a computer, use it to output data from your controller to your computer (great for debugging), or even use it to operate other electronics such as digital video cameras. Usually the microcontroller would require an external IC to handle everything, such as an RS232. To learn more, read my microcontroller UART tutorial.

Timers

A timer is the method by which the microcontroller measures the passing of time - such as for a clock, sonar, a pause/wait command, timer interrupts, etc. To learn more, read my microcontroller timer tutorial.

I^2C

I^2C (pronounced 'I-squared-C') is also useful for communicating, but I have never used it. Just make sure your controller has some method of communicating data to you for easy and effective debugging/testing of your robot programs. Its actually somewhat complicated, but usually the manufacturer has simplified it so all you have to do is plug-n-play and do a few print statements. To learn more, read the I^2C tutorial.

Motor Driver

To run a DC motor you need to either have an H-Bridge or a Motor Driver IC. The IC is great for small robots that do not exceed 1 or 2 amps per motor and the rated motor voltage is not higher than about 12V. The homemade H-Bridge would need to be used if you wanted to exceed those specs. There are a few H-Bridge controllers commercially available to buy, but usually they are way too expensive and are designed for battlebot type robots. The IC is small, very cheap, and can usually handle two motors. I highly recommend opting for the IC. Also, do not forget to put a heatsink onto the motordriver. Motordrivers give off pretty fireworks when they explode from overheating =)

Another interesting note, you can stack IC's in parallel to double the allowable current and heat dissipation. Theoretically you can stack as many as you want, as long as the current is high enough to still operate the logic of the IC. This works for voltage regulators too.

Output Indicators

Im referring to anything that can be used for debugging by communicating information to you. LED's, buzzers, LCD screens, anything that gives output. The better the indicator, the easier the debugging. The best indicator is to have your robot tethered and print or data log sensor and action data to your computer, but it isn't always possible to have your robot tethered.

Programming Languages

The lowest form of programming languages is the machine language. Microcontrollers need to be programmed with this.

An example of machine language:

3A 10 51

E6 DF

32 38 00

Obviously neither of us could ever memorize what all those seemingly random numbers and letters do, so we would program in a higher language that makes much more sense:

If (language = = easy)

print "yay!";

These higher languages would then be compiled automatically into a machine language, which then you can upload into your robot. Probably the easiest language to learn would be BASIC, with a name true to itself. The BASIC Stamp microcontroller uses that language. But BASIC has its limitations, so if you have any programming experience at all, I recommend you program in C. This language was the precurser to C++, so if you can already program in C++, it should be really simple for you to learn. What complicates this is that there is no standard to programming microcontrollers. Each has its own features, its own language, its own compiler, and its own uploading to the controller method.

This is why I do not go into too much detail because there are too many options out there to talk about. The support documents that come with the controllers should answer your specific questions. Also, if you decide to use a PIC, understand that the compiler program (at least the good ones) can cost hundred of dollars. Most microcontrollers also require a special interface device between your computer and the chip for programming which could also cost from $10-$40.

Costs

With possibly the exception of DC motors, the microcontroller is the most expensive part of your robot. There is just no escaping the costs, especially for the beginner. But remember, after buying all this for your first robot, you do not need to buy any of it again as you can reuse everything. So here is the breakdown of costs. The chip itself, without augmentation, would only cost dollars. But understand the chip is useless without the augmentation, so you would need to do it yourself if you do not buy it already augmented. This could potentially cost just as much with the augmentation, and could cause you many frustrations.

If however you are more experienced (and for some odd reason still reading this), you can customize your own circuit to do exactly what you want. Why have a motordriver when you are only using servos anyway? If you decide to buy an augmented MCU, the cost will range from about $50-$150. To compile your program, you would need to get special compiling software. Atmel and BASIC Stamps have free compilers. PIC's however have fairly expensive compilers. There are some free ones available online, but they are of poor quality in my opinion. CCSC PIC C compiler is about $125, but I think it is worth getting if you are going to use PIC's.

You will also need an uploader to transfer the program from your computer to the chip. This generally requires more special software and a special interface device. The Cerebellum PIC based controller has this built in which is really nice and convienent, but for any others expect to spend from $10-$40. People often opt to just make their own as the circuit isnt too complicated.

As a prototyper, what you probably want most is a MCU development board. These augmented microcontrollers are designed for the prototyper in mind. To find these augmented MCU's, do a search for 'pic development board,' 'atmel development board,' 'stamp development board,' etc.

Conclusion

If you have more specific questions about microcontrollers, or would like me to go into more detail about something, just write me and I will.

Update

I've created a microcontroller product, called the Axon, that's both easy to learn and powerful in features. I use it for all my robot creations now, and will continuously release source code updates and tutorials using it. Feel free to check it out!

Axon Microcontroller

Neural Networks and Machine Learning

2011-08-11T03:45:00.000-07:00

Neural networking is the science of creating computational solutions modeled after the brain. Like the human brain, neural networks are trainable-once they are taught to solve one complex problem, they can apply their skills to a new set of problems without having to start the learning process from scratch.

The Lab seeks models which combine the best aspects of neural network mechanisms and symbolic artificial intelligence machine learning paradigms. Neural networks and machine learning algorithms represent a dramatic departure from conventional programming techniques. Rather than explicitly build a program to solve a problem, examples, called "training sets," of a type of problem are given, which the neural network "learns" how to solve. The network can then be presented with new examples on which it was not trained, known as "test sets," and it will use the skills it gained from the training set to formulate solutions. For many tasks, neural networks actually outperform human experts. For example, a doctor must go through years of training to learn to diagnose a disease on the basis of a set of symptoms. A neural network, in comparison, would diagnose a disease by first learning from a training set made up of symptoms with the correct diagnoses, and then would formulate a diagnosis when presented with new symptoms on which it was not trained.
Some of the problems considered in the Neural Networks and Machine Learning Laboratory are control problems, such as controlling a large flock of independent robots. Just as a person who understands how to drive a car can transfer that knowledge to driving a truck, a computer which controls one robot should quickly learn how to control a whole flock. Other problems being solved in the lab are planning and classification tasks. One project would allow computers to be able to recognize individuals' facial features and thus pick individuals out of photographs. Other applications include automatically sorting music libraries and classifying species of plants and animals.

Basic Science and Mathematics: Which Topics Are Most Needed?

2011-06-14T22:49:00.000-07:00

Basic Science and Mathematics: Which Topics Are Most Needed?

The engineering technology faculty at Wake Technical College undertook a study in the fall of 1978 to determine if our basic science and mathematics offerings were relevant to graduates' needs on the job. Since 1964, when Wake admitted its first engineering technology students, the engineering technology division had expanded to six fully accredited two year associate degree curricula with over 200 students enrolled. Feedback from employers and graduates indicates that the curricula are equipping graduates with the necessary entry ¬level skills. The explosion in technological information, however, has placed demands on two year ET curricula to include more state of the art subjects at the expense of fundamental science and mathematics subjects. Since only a limited number of topics can be covered in two years, ET curriculum planners must scrutinize subject matter to ensure that it does help to prepare students for jobs as science and engineering technicians, and to avoid technical obsolescence as their field changes.

We surveyed graduates of Wake's six ET programs and their employers to learn what they considered the basic science and mathematics topics most needed by engineering technicians on the job. We also sought to obtain comments about topics not listed on the survey which may be needed.

Of the 697 participants selected to receive our questionnaire, 470 had graduated from one of the six ET programs at Wake from 1969 through 1977, and 227 were employers of graduates of these programs. The questionnaire was drafted by a group of department heads and a second group of people involved with two and four year ET programs nationwide.

Results

Table 1 summarizes the basic science and mathematics topics needed by engineering technicians, as determined by the 29 percent of the enployers and 23 percent of the graduates who responded to the questionnaire. The findings are based on response patterns for a given item in which at least the group of employers or the group of graduates agreed with the combined group of respondents by a majority response in eitherthe essential (E), desirable (X) or not needed ( ) categories.

1) The strongest support for the items under mechanics came from respondents in the architectural, chemical, civil engineering, and industrial engineering technologies.

2) The items under the fundamentals of electricity/electronics were unani¬mously supported by respondents in the computer, electronic engineering, and industrial engineering technologies.

3) All groups of respondents supported the study of the general theory of

light, but only the electronic engineering technology respondents indicated support for all the items under light.

4) The study of the items under sound was supported by three groups of respondents: architectural, computer, and electronic engineering technologies.

5) All groups of respondents supported the study of heat.

6) Modern physics was important only to responding chemical technicians and electronic engineering technicians.

7) Only the chemical technology respondents supported the study of the chemistry subjects.

8) Items listed under biology were needed only by chemical technicians.

9) Civil engineering technicians were the only group who needed a knowledge of all the items under geology.

10) The two items under data processing were important to all but architectural technicians.

11) The study of algebra, trigonometry, logarithms, geometry, analytic geometry, and calculus was supported by all respondents.

12) The chemical, civil, electronic, and industrial engineering technology respondents indicated support for the items under statistics.

At the end of the questionnaire, the study participants were given the opportunity to make further comments, such as to be more specific with regard to certain topics or to list further topics they thought should be included.

In general, their comments addressed specific skills and knowledge required by technicians to do well in their jobs. The comments did reflect an awareness of the rapidly changing requirements in engineering technology and an appreciation of the value of basic science and mathematics in keeping abreast of these changes.

In addition to determining the basic science and mathematics topics most needed by engineering technicians, the study revealed several other trends:

Graduates and employers in all six engineering technology fields indicated that a knowledge of mathematics ranging from algebra to calculus was important for engineering technicians. The extent to which a certain mathematical topic was important depended upon its direct usefulness in solving day to day problems on the job. Support for the study of other mathematical topics resulted from a need for a foundation in mathematics which would afford the technician an opportunity to keep abreast of technological changes, as well as to develop analytical skills.

The respondents believed that an engineering technician needs a knowledge of basic science topics, which provide a foundation for applying skills and knowledge in their particular field. For example, chemical technicians indicated support for a study of the basic science of chemistry. Electronic technicians, on the other hand, indicated an interest in the fundamentals of electricity and electronics that explain the electrical phenomena associated with the application of electronics and electricity.

In the case of data processing, all participants except those in architectural technology believed that a knowledge of at least one scientific programming language was important. In addition, respondents indicated an interest in the study of COBOL.

Analysis of the response patterns of employers and graduates showed that graduates were more supportive of a knowledge of basic science and mathematics topics. Employers, on the other hand, tended to support only those topics that

were immediately useful in solving day to day problems. This difference in response patterns can be attributed to the desire of engineering technicians to stay abreast of technological change, while their employers appear interested primarily in the knowledge and skills that contribute to immediate productivity.

Engineering Technology Definitions,Yesterday, Today, and Tomorrow

2011-06-08T05:30:00.000-07:00

Yesterday

Before establishing the definition, it seems desirable to provide a brief history of engineering. This will demonstrate that although “we’ve come a long way, baby,” the rate of change in engineering is progressing at a breathtaking pace, particularly when compared to the early history.

Three developments in engineering in the nineteenth century have changed the course of history and altered the quality of human life. The first was the expansion of the Industrial Revolution. The second was the emergence of civilian engineering as a profession, distinctly emphasizing the importance of technical and scientific education as prerequisites for the practice of engineering. The third and most important development, however, was the introduction of applied science as a new method of approach to the achievement of engineering advances.¹

Men who earned a living from the practice of engineering, or “professional engineers, “ had begun to appear in France during the seventeenth century. The first schools for instruction in engineering were established by the French in the in the eighteenth century. However, these institutions largely employed the apprenticeship method of instruction and only occasionally were general theoretical lectures given. After the French Revolution, these schools began instruction in such basic sciences as mathematics, physics, and chemistry.²The rise of engineering science in the eighteenth century was typical of the Age of Reason with its emphasis on the use of the scientific method. This drastically altered the practice of engineering and the concept of technical education in the nineteenth century. For example, when it became apparent that a structure scientifically designed to perform a specific function was more economical than one designed on the basis of experience, engineering science began to develop rapidly. It also became clear that technical schools were far more competent for teaching the new science than was the age-old institution of apprenticeship.³

The U.S. Military Academy at West Point was founded in 1802, and in 1817 became the first school in the United States to offer an engineering program. Norwich University in Vermont was established in 1819 and is reported to have offered engineering in the early days. Rensselaer Polytechnic Institute was founded in 1824 and it granted its first engineering degree in 1835.~

In 1806, shortly after the military academy at West Point was founded, Webster’s Dictionary defined “engineer” as follows:

engineer, n. One who directs engines or artillery.

engineer, v.1. To manage engines.⁵

There was no definition for “engineering” in the 1806 Dictionary.

Engineering instruction was confined to civil engineering in the early years. A school of mines was founded at Columbia University in 1864, and in 1865 M.I.T. opened, offering programs in mechanical, mining, and civil engineering and in what was called “practical chemistry.” With the passage in 1862 by the United States Congress of the Morrill Act, an “Act donating Public Lands. to the several States and Territories which may provide Colleges for the benefit of Agriculture and the Mechanic Arts,” the number of engineering schools in the United States

was increased by more than five times. “These schools trained men who could apply the increasing wealth of scientific knowledge to practical problems, and they had a large part in transforming the industrial, economic and social life of the nation.”⁶

In October of 1 933, ECPD adopted the “Minimum Definition of an Engineer.” A careful review of the definition indicates that ECPD did not attempt to define engineer at all but merely framed the minimum qualifications required for licensing for professional registration.

As a means of improving the quality of education for technicians, in 1945 ECPD set up a program for accrediting technical institute-type curricula. Since the work of the technician overlapped that of the engineer, clear recognition and identification of the roles became necessary. The 1953 ECPD Annual Report set forth specific definitions of “professional engineer” and “engineering technicians.” In 1961 ECPD adopted the following definition:

Engineering is the profession in which a knowledge of mathematical and natural sciences gained by study, experience and practice is applied with judgment to develop ways to utilize economically the materials and forces of nature.

It is interesting to note that ECPD at this time adopted seven paragraphs attached to this definition to clarify words and phrases. In 1962 ECPD modified the definition by adding a terminal phrase, “for the benefit of mankind.” That definition is still the current definition utilized by both ECPD and the American Society for Engineering Education (ASEE). In 1962, also, ECPD created the Engineering Technology Committee to perform the functions of accreditation for the Council. ~n 1963 ECPD adopted the following definition:

Engineering technology is that part of the engineering field which requires the application of scientific and engineering knowledge and methods combined with technical skills in support of engineering activities; it lies in the occupational spectrum closest to the engineer.

(a) Engineering technology is identified as a part of the engineering field to indicate that it does not by any means encompass the entire field and also to differentiate it from other types of technology in areas such as medicine and the biological sciences. The engineering field is viewed as a continuum extending from the craftsman to the engineer. Engineering technology falls, in the continuum, between the craftsman and the engineer and closer to the engineer than the craftsman.

b) Engineering technology is concerned primarily with the application of established scientific and engineering knowledge and methods.

(c) Technical skills such as drafting are characteristic of engineering principles and methods. Engineers graduated from scientifically oriented curricula may be expected to have acquired less of these skills than previously and the engineering technician will be expected to supply them.

(d) Engineering technology is concerned with the support of engineering activities whether or not the engineering technician is working under the immediate supervision of an engineer. It may well be that in a complex engineering activity he would work under the supervision of an engineer, a senior engineering technician, or a scientist.

In 1967 ECPD accredited the first baccalaureate engineering technology program.

Today

The 1963 definition of engineering technology based on associate degree programs has remained unchanged.

Tomorrow

In the spring of 1977 an ASEE ad hoc committee was appointed to review the published definition of “engineering technology.” After considerable deliberation the committee members concluded that in order properly to define engineering technology the definition of engineering would also have to be considered. The resulting document which was formulated has been refined through six drafts and widely circulated to representatives of engineering and engineering technology from both education and industry. The extensive favorable reaction to the definition from all segments indicates that the ASEE approval at this time would be a most appropriate, positive step toward verifying the relationship between the various components of the engineering profession. The definitions as developed by the ASEE committee follow:

Definition

Engineering is the profession in which a knowledge of the mathematical and natural sciences gained by study, experience, and practice is applied with judgment to develop ways to utilize economically the materials and forces of nature for the benefit of mankind.

Scope

The scope of the engineering profession in industry, government, and business is extremely broad. It includes research, development, design, production, construction, administration, testing, maintenance, and sales. There is a wide spectrum of technical personnel within the engineering profession.

Academic Programs

To embrace this total spectrum, academic institutions offer associate, baccalaureate, and advanced degree programs in engineering and engineering technology, as well as other programs in related areas. Graduates of these programs have the opportunity to advance in their careers depending upon their ability, personal characteristics, and professional development as well as their initial and continuing academic preparation. Undergraduate academic programs in engineering and engineering technology overlap considerably and programs with similar titles will vary from one institution to another. However, the following characteristics are usually found.

Baccalaureate Engineering: programs are characterized as including advanced mathematics through differential equations, basic physical science, engineering science, and engineering design courses which emphasize research, conceptual design, systems, and development.

Baccalaureate Engineering Technology: programs are characterized as including applied mathematics through differential and integral calculus, applied sciences, and technical courses which emphasize the application of technical knowledge and methods to current day-to-day industrial problems.

Associate Engineering Technology: programs are characterized as including mathematics through the elements of calculus, applied sciences, and applied technical courses in a specific technical discipline which emphasize technical support of engineering activities.

Placement :of graduates from these different types of programs varies considerably depending upon the region in which the programs are offered and the specific needs of industry at a particular time. However:

The baccalaureate-engineering graduate would most likely aspire to an entry-level position in conceptual design, systems engineering, or product research.

The baccalaureate engineering technology graduate would most likely aspire to an entry-level position in product design, technical operations, product development, production, or technical service and sales.

The associate engineering technology graduate would most likely aspire to an entry-level position in support of engineering activities.⁸

Dr. Walter E. Thomas, Dean

School of Technology and Applied Sciences

Western Carolina University

NOTES

1. Richard Shelton Kirby, et al., Engineering in History (New York: McGraw-Hill,

1956), pp. 327-28.

2. Ibid.

3. Ibid.

4. “Engineering Education,” Encyclopedia Britannica, Vol. 8 (1968), p. 392.

5. Noah Webster, A Compendious Dictionary of the English Language (A facsimile of the first 1 806 edition), Bounty Books, A Division of Crown Publishers, p. 103.

6. Ibid., p. 393.

7. Annual Report, Engineers’ Council for Professional Development (1961), p. 18.

8. Weidhass, Thomas, Rath, and Ungrodt, American Society for Engineering Education ad hoc committee report (sixth draft), 1978.

PopCARD: Pop Machine Cash Card

2011-05-14T23:59:00.000-07:00

PopCARD: Pop Machine Cash Card

The machine is made by Dixie Narco, and it turns out the machine is quite common and very capable, although by vending standards it is now considered "out of date". But it's good enough for my needs. I put it in the hallway of my building and use it to sell a variety of drinks to my neighbours.
Just 6 days ago, as I was fishing around for change to buy a drink from my own machine, I wondered how difficult it would be to add a key-override for myself, so I could buy drinks without having to put money in. That idea quickly ballooned into building a full-fledged cash card system that all of my neighbors could use. But, what was the best way to make the machine think that money had been inserted without actually doing it?
Digging through the service manual for the machine, I found and then quickly ruled out using the "modern" protocol that coin changers and credit card readers use to interface with the machine. This protocol is called MDB, short for Multi Drop Bus. It's a powerful protocol, but it has an irritating 9-bit word with an 11-bit transmission protocol, and it seemed to be much too complicated for what I really needed. So, I turned my attention to the mysterious port on the machine's main board, labeled "P8", designated for dollar bill acceptors.

In this photo, you can see the port circled in red. It is labelled "Bill Validator Interface" and has 8 pins. However, no other information about the connections was forthcoming. The service manual only contained information about compatible changers, but that didn't get me far. I spent hours digging around on the internet as well as speaking to the authorized distributer for Dixie-Narco in Canada, with no luck.

The big break came when a phone call to 'Dennis', a tech rep at Crane (the company that bought Dixie-Narco), was able to find me the pinout of the port. Here's what he gave me:

1 - Vend NO
2 - Vend COM
3 - Low Level Inhibit COM
4 - AC HOT
5 - AC Neutral
6 - Low Level Inhibit 2
7 - Low Level Inhibit 1
8 - High Level Inhibit 1

So, those pinouts looked about as greek to me as I'm sure they do to you. And with 110V right on the same connector, I wanted to be really sure of the wiring before I put any connections to them! With help from my friend Justin, we were able to figure out that shorting Vend NO and Vend COM twice caused the machine to add a credit of $1.00. In addition, I discovered that when 5V is present on Low Level Inhibit 2, the machine is ready to accept money, and otherwise it is not.

Armed with this information, I bought a new Arduino, an Adafruit ethernet shield, a Wiznet ethernet module, an LCD screen, and an RFID reader. Here's the initial set up:

The basic operation of the system is like this: A user scans their card, which is read via the RFID reader. The ID is sent to a piece of software running on one of my servers, which compares it to a database and retrieves the user name and their current credit amount. This is then displayed. If the vending machine is ready to accept money, pressing a "buy" button subtracts $1 from the account and places it in the machine. The user can then use that money to make a beverage purchase.

The final setup before it was mounted into the pop machine. I added a speaker to provide audio feedback. It plays the "1-up" sound from Mario!

Inside the machine, the relay board and the Arduino were mounted into a plastic case.

Since we don't have dollar bills in Canada, my machine doesn't have a bill changer. So I used the bill changer opening as an access hole for the LCD display, RFID reader, and pushbutton. The alligator clips are temporary -- I need to buy some spade connectors.

Here's that 8-port connector on the back of the vending control board. I found that a 6-pin PCI-E power cable matched the bottom 6 holes perfectly, while also leaving the 110V AC holes not connected.

On the front of the machine, I create a (crappy) template to display instructions and tell people what to do:

This is probably one of the more complicated Arduino-based builds I have done, and I am very happy with how well it works!

View the Arduino source code for the pop machine interface here.

Here's a schematic of the electronics. Click to enlarge.

Standard Arduino Works With Android Open Accessory

2011-05-14T23:26:00.000-07:00

Standard Arduino Works With Android Open Accessory

A lot of people have been put off by the price of the reference hardware kit, which is roughly $390. What’s worse, they appear to be sold out until end of May, and Microchip’s cheaper ($80) alternative doesn’t arrive until July. So instead of waiting I decided to write a guide on how to get an ADK-capable Arduino for about $55.
Since the ADK reference design is based on Arduino and Oleg Mazurov’s excellent USB host shield, it stands to reason that we should be able to build our own hardware kit from these components. I already had these parts lying around from my work on MicroBridge, so I decided to ‘port’ their code, which in reality means just changing a couple of pin definitions.
disclaimer: Since I don’t have a phone that supports accessory mode I have no way to verify that this actually works. What I can see however is the output from the Arduino which seems to indicate that everything is working as it should be. If anyone has actual Android hardware that supports ADK and would like to help me test this, let me know!
Hardware
In order to replicate this you’ll need two things:

An Arduino board or compatible. You can get an Arduino from places like Sparkfun, although cheaper clones can be had on Ebay for as low as $20.
A USB host shield. You have the choice of either Oleg’s USB host shield, which will run you $40, or Sparkfun’s cheaper variant which sells for $25.

You can either get a ‘regular’ 328p-based Arduino or an Arduino Mega. The higher price of the Mega gives you extra IO pins, which you might actually need since the host shield occupies pins 7-13.
Sparkfun’s shield is cheaper but has some drawbacks. Firstly it does not work with Arduino Mega variants because these boards have their SPI pins in a different location. Oleg’s 2.0 shield solves this by connecting to the ICSP header on the Arduino, which is in the same location on all variants. Second, Sparkfun’s shield requires an external power source to be connected the the Arduino board. Finally, it’s not stackable, which is really annoying when you’re trying to drive servos, motors, and so forth.
Here’s a picture of the setup I use. As you can see, I use Sparkfun’s shield and an Arduino Uno. Note also the external power supply to power the phone. If you get this combo from Sparkfun, it’ll cost you about $55 ex shipping.

Firmware
While the ADK reference software includes Oleg’s USB library, they slightly modified the code, hardcoding the pin assignment to the max3421e chip. Unfortunately this breaks compatibility with the Arduino shields, so I had to patch their code a bit to make it work again. All I really had to do is add some #defines and it worked pretty much out of the box from there.
To try it out for yourself, download the ADK software package and follow the installation instructions on the ADK page. Instead of installing the USB host lib from their package, get the patched version here and copy it into the libraries directory of your Arduino installation. Remove all the stuff from demokit.pde that uses the demo shield (joystick, RGB leds), and you should be good to go.
You should see the following output on the serial port:

Start
Device addressed... Requesting device descriptor.
found possible device. swithcing to serial mode
Data packet error: 5could not read device protocol version

Device addressed... Requesting device descriptor.
found possible device. swithcing to serial mode
Data packet error: 5could not read device protocol version

Et cetera. This means that the electrical wiring to the shield is in working order and the max3421e is finding the phone. The ‘Data packet error: 5′ means that my phone is not responding to the non-standard control request, which it shouldn’t, since it’s not an accessory-capable device (yet).
Conclusions
As far as I can tell following this guide should give you a slightly more economical Android accessory device compared to the reference kit. Until I get my hands on a phone I cannot test it, so if anyone out there has a capable device or knows how to hack support for it onto a rooted ZTE Blade, let me know. When ADK makes it into Cyanogen mod I’ll certainly flash it on one of my blades and let you know how it goes.
Finally, if anyone out there has one of those cool ADK demo kits and wants to lend me one, feel free to contact me. I’d like to port MicroBridge to it so that it can be used it with pre-2.3.4 devices.
update: much thanks to RobotFreak and Follower for confirming that this setup works! Apparently some versions of avr-libc require ‘PORTB1′ instead of ‘PB1′ to compile correctly

New laser will be powerful enough to rip apart space itself

2011-05-02T22:17:00.000-07:00

New laser will be powerful enough to rip apart space itself

The European Commission has approved the construction of three gigantic new research lasers, with the option for a fourth that would, for an instant, be several hundred times more powerful than the entirety of the power generated by our civilization. The hope is that this will be enough energy to actually conjure virtual particles out of nothingness.

At peak power, the fourth laser in Europe's Extreme Light Infrastructure project (or ELI) will combine ten beams into a single pulse measuring 200 petawatts. 200 petawatts is significantly more power that our entire race generates at any given moment, and in fact more total power than Earth receives from the sun.

Needless to say, this is not the type of laser that you just turn on and wave around for your cat to chase. The only way that this massive amount of power is able to be harnessed is if the amount of time that it's being used for is insanely small. The 200 petawatt pulses will only last 1.5 x 10^-14 second, which is about the same amount of time that it takes for light to travel from one side of a human hair to the other, if you shave the hair down by 90%.

The point of all this is to try to explore some of the weirdness of quantum mechanics, which suggests that space is actually a giant party of random particles that are popping in and out of existence too fast for us to see. The hope is that a laser this powerful might actually be able to tear apart the vacuum of space-time itself, revealing the matter and antimatter underneath.

what is solid state electronics

2011-05-02T22:14:00.000-07:00

what is solid state electronics

Integrated circuit technology and its later development, Micro systems technology, make good use of a multitude of processes and analysis methods developed and refined during the second half of the last century. The impact on society from this evolution has been tremendous.

Electrical and Electronics Engineer,s Careers

2011-04-23T07:54:00.000-07:00

Electrical and Electronics Engineer,s Careers

Electrical and electronics engineers are involved in a wide variety of technology ranging from huge global positioning systems which can pinpoint the location of a moving vehicle to gigantic electrical power generators. These engineers are responsible for designing, developing, testing as well supervising the production of electrical and electronic equipment and machinery. Broadcast and telecommunication systems, electric motors, controls of machinery, lights and wiring in building complexes, vehicles, aircraft, radar and navigation systems, power generation, control and transmission devices which are used by electric utilities are all examples of equipment built by these engineers. They may also work in fields which relate to computers and IT. However, those engineers who deal exclusively with computer hardware are called computer hardware engineers- an engineering specialty with is discussed separately in the Handbook.

Electrical and electronics engineers may choose to specialize in various areas like power generation, transmission and distribution; communications; manufacture of electrical equipment etc or a one particular specialty within these area; foe e.g. industrial robot control systems or aviation electronics. These engineers are involved in designing new products, writing requirements for their performance, as well as developing maintenance schedules and charts. Testing equipment and machinery, solving operation problems, estimating time and cost of electrical and electronic products also come under their job.

In 2002, electrical and electronics engineers had around 292,000 jobs and constituted the largest branch of engineering. Most of these engineers were employed in professional, scientific, and technical services firms as well as government agencies. Manufacturers of computer and electronic equipment and machinery also employed these engineers. The remaining engineers were absorbed by firms which deal in wholesale trade, communications, and utilities.

Electrical and Electronics Engineering Job and Employment Opportunities

Favorable employment opportunities are predicted for electrical and electronic engineers. Job opportunities which would result from retirement and transfers of existing electrical and electronic engineers are in proportion with the degree granted to these graduates and thus demand for these workers roughly equals their supply.

Although the employment opportunities for electrical and electronic engineers are predicted to grow through 2012, their growth rate is slower than the growth of other occupations. Even though there is a rise in demand for electrical and electronic products, (including advanced communication goods) defense-related electronic products, and consumer electronics equipment, competition from abroad and increased use of electronic and electrical engineering services in foreign countries, hinder domestic employment. The growth rate of employment opportunities are predicted to be highest in the service industries which provide electronic engineering expertise.

It is imperative that electrical and electronic engineers continue their education. Those who do not keep abreast of latest advances in technology are at the risk of either loosing jobs or loosing good promotion opportunities

Electronics Engineer Job Description

The job duties and responsibilities of electronics engineer include:

• Researching, designing, developing and testing electronic products and components

• Designing electronic circuit, components and integrated systems

• Drawing plans and specifications for projects

• Taking care that the projects fulfill electrical safety regulations

• Designing test control apparatus and tools

• Handling the design of electrical devices

• Keeping abreast of the developments in the field of technology

• Writing technical reports

• Writing specifications of electronic products

• Developing user-friendly interfaces

Education Requirement

To enter this field, you are required to have a Bachelor’s degree in electrical engineering. A considerable experience in designing electronic systems is also necessary for this job. You may also require a combination of experience and training. There are a few colleges that provide training. Some colleges conduct work-study programs in which students can avail the opportunity of on-the-job training. If you want to do a job related to research or teaching you will need a Master’s degree. These engineers also need a license if their work influences the life and property of others or they provide services to public. Such types of engineers require degree from an engineering school, four years experience and passing grade on the state examination.

Skills Required

• Outstanding skills in math, science and technology and the field of IT

• Skills to develop and maintain budgets

• Aptitude to clearly explain the design ideas

• Ability to design electronic circuits

• Extra-ordinary communication skills

• Ability to maintain good working relations with the personnel

• Skills to analyze needs of electronic system

• Decision-making skills

• Ability to understand the electrical safety and health rules

Getting Job

You can find the job easily but extensive efforts will be required on your part. You will have to search internet, job ads on newspaper and read professional journals. You may also try your luck by applying to the private organizations and government agencies. Civil service examination will have to be passed to get a government job. Wherever you apply for the job, you will have to prepare a resume first and then apply for a job. You

can find a number of electronics engineer resumes on different sites for your help and guidance. After reading one or two resumes, you will be able to compose your own.

Advancement Opportunities

Electronic engineers can be promoted to managers and executives. Those who get extra training may be promoted to highest paid specialists. Experienced engineers can start their own engineering firm.

Salary

The salary of electronics engineers vary according to their experience.

Historical Earnings Information

In 2002, the median salaries received by electrical engineers were $68,180 annually. The middle 50 percent received salaries between $54,550 and $84,670 while the lowest 10 percent earned below $44,780. The highest 10 percent earned above $100,980. In 2002, the median annual earnings in the industries which employed the largest numbers of electrical engineers were:

• Scientific research and development services – $77,410

• Semiconductor and other electronic component manufacturing – $72,670

• Electric power generation, transmission, and distribution – $71,640

• Navigational, measuring, electro-medical, and control instruments manufacturing – $70,430

• Architectural, engineering, and related services – $66,980

In 2002, the median earnings of electronics engineers (except computer engineers) were $69,930 annually. The middle 50 percent received salaries between $55,930 and $85,980. The lowest 10 percent received salaries below $46,310, and the highest 10 percent earned above $103,860. In 2002, the median annual earnings in the industries which employed the largest numbers of electronics engineers were:

• Federal government – $78,830

• Architectural, engineering, and related services – $72,850

• Navigational, measuring, electro-medical, and control instruments manufacturing – $70,950

• Semiconductor and other electronic component manufacturing – $70,800

• Wired telecommunications carriers – $62,670

In a 2003 slaary survey conducted by the National Association of Colleges and Employers, candidates with a bachelor’s degree in electrical/electronics and communications engineering earned starting salaries of $49,794 on an average in a year; those with a master’s degree earned around $64,556; and those with a Ph.D. received $74,283on an average.

Seasoned Engineers may earn even more.

Electrical and Electronic Engineering Study

Why Study Electronics Engineering Technology?

As an Electronics Engineering Technology student, you will be able to develop a background in the areas of circuit analysis, interfacing and installation of electronic systems, communications systems, use of specialized equipment including oscilloscopes, spectrum analyzers, HART analyzers, and many other types of instrumentation. For example, in depth courses provide you with the capability of doing functional design and building up of circuits for sensor interfacing, communications over air, cable and fiber.

You will be prepared for a technical career in a wide variety of electronics, electrical, and related fields. You may find employment in areas related to automation engineering, computer electronics, telecommunications, power systems, general manufacturing, product design and testing, quality assurance, field engineering, prototype fabrication, process management, and customer service. You may be able to pursue the professional engineer license.

Choosing an Electronic Engineering Course

Electronics is fundamental to many of the things we take for granted today. Everything from mobile phones to aircraft and medical equipment relies on electronics, and it is difficult to think of any area of life that has not been affected by developments in electronics.

Technology, and particularly electronics, is developing at a more rapid pace than ever before. This makes the job of the Electronic Engineer both exciting and challenging, but it also means that there are great rewards for engineers, both in terms of remuneration and job satisfaction.

An International Career

Today, engineering in general - and electronics in particular - is an international business. Most of the well-known companies in electronics operate not just in several countries, but across continents, and many smaller companies depend on international trade for their business. In order to compete in this situation, companies recruit engineers from around the world. To succeed, engineers need to have internationally recognised qualifications.

Qualifications themselves are only one of the benefits to be gained from study abroad. A successful career depends on who you know as well as what you know, and the people that you study with are likely to become important contacts once you leave university. If you choose a suitable course, the people who are classmates today will be the leaders of tomorrow.

Britain has long been recognised for its success in engineering and technology innovation, and this reputation is built on an excellent education system. The engineering knowledge you gain in a British university is, of course, the same as you would in any other country, but there are differences in the way these are taught and learnt from many others. You need to be aware of these differences of approach and expectation before you start to study.

In most courses in Britain, there is a lot of emphasis placed on learning to think for yourself and study on your own. This can come as a shock to students who are used to being given all of the information they need, but independent learning skills are vital once you start a real job, solving problems that have never been encountered before. Fortunately, courses develop these skills gradually, with plenty of support available to ensure your confidence is built up.

Engineering courses in Britain are shorter than in many other countries, being three or four years in length. Most students complete the course within this time, since it is unusual for students to repeat years. So although course fees may seem high, the overall cost of study in Britain can be lower than elsewhere.

Choosing a Course

Deciding what to study and where to study it is a big decision, both in terms of time and money, and so it is vital that you choose the right course and the right university. To make the right decision you have to take account of many different factors, as outlined below.

Looking at the lists of courses available, it is easy to be confused by the wide choice, ranging from straightforward Electronic Engineering to more specialist courses, such as communications, semiconductor devices or microelectronics. There is also a wide range of joint courses, combining electronics with computer science or language studies, for instance.

An Electronic Engineering course will cover all of the key knowledge and skills required to become a successful engineer, including the skills required to rapidly become familiar with new developments, while a more specialist course may neglect some of these topics in order to cover the more specialist subjects. This can be an advantage for those wanting to follow a career in the particular specialisation, but if you do not know which specialisation would suit you best, then a more general course may be more appropriate.

Fortunately, many courses begin by covering general Electronic Engineering, but allow specialisation in later stages of the course. A typical course may be fairly general for the first two years, with specialisation available in the third and fourth years. While following a joint course will give additional skills, it will allow less time for the core electronics knowledge, and so choosing an unrelated subject can leave the graduate not fully qualified in either of the subjects contributing to the degree.

Quality Courses

Besides deciding which type of course would suit you best, it is important to choose the right university. Each university sets its own curriculum, decides the teaching methods that will be used, and the qualifications required for entry. The facilities available within each university, the qualifications of the staff, and the specialisations available will also differ. It can be difficult to know which universities will offer the best education, especially as each institution wishes to promote its own courses. Although the reputation of a university may give an indication of the quality of education, the fact that they have a good reputation does not necessarily mean that the Electronic Engineering course will be equally good. Similarly, some of the best universities for the study of electronics are not generally recognised.

In order to help choose a suitable course, there are a number of sources of independent information. The British Government established the Quality Assurance Agency to assess the quality of education provided by each university in particular subjects. In order to make these assessments, a panel of experts visit the university to observe teaching, talk to students, graduates and their employers. They then award a grade out of 24 points. The panel also produce a report covering each of the six areas of the assessment. The assessments for Electronic Engineering, involving 76 institutions, were carried out between 1996 and 1998. The reports on each institution are publicly available on the QAA Website: www.qaa.ac.uk.

A total of ten universities gained the maximum possible grade (24 out of 24), but it is important to look at the individual reports, since these specify what the courses aim to achieve. The assessment is a judgement of how well these aims are achieved.

A second factor to consider in quality of courses is accreditation by professional bodies. In the case of Electronic Engineering, this is the Institution of Engineering and Technology (IET). The IET looks at both the subject matter and the way it is taught, and can award accreditation for three different levels of course. Accredited Master of Engineering (MEng) and Bachelor of Engineering (BEng) honours courses lead eventually to chartered engineer status, while other degree courses can lead to Incorporated Engineer status. Although accreditation of a course means that it has met the required standard, if a course is not accredited this does not necessarily mean that it is not a good course. A course can only be fully accredited once students have graduated, and so it may take four to five years before a new course can be accredited. Courses that address new technologies may be very relevant to industry, but because they are new, they may not be accredited. Courses that combine electronics with other disciplines may also not be accredited because they do not contain sufficient core Electronic Engineering material, but this does not mean they are not worth considering if the subject is what you want to study.

The choice of whether to study an MEng or BEng (honours) course can be a difficult one. MEng courses tend to last four years, while BEng's are generally one year shorter. This does save money on fees and living expenses, but if your eventual aim is to gain chartered status, a further year of academic study is required following graduation from a BEng.

Your choice of university may also take account of the cost of living. This can vary a great deal depending on the location of the university. Although London, for example, has many attractions for students, the costs of accommodation, transport and food all tend to be higher than in other parts of the country. Worrying about money and the need to work can be a big distraction from your academic work.

With the choice of different subjects, course structures and universities open to students of Electronic Engineering, it can seem overwhelming. You should try to decide what you really want to get out of your course. Then look for independent information, try to talk to someone who has studied at the universities you are interested in and, if you are unsure about what a particular course involves, or whether a particular university would suit you, then contact the Department with your questions. You will be able to learn a lot from the way they answer, both about the courses and the way that they treat students.

Why should You study Electrical and Electronic Engineering?

• You enjoy maths and science and want to make the most of your excellent grades.

• You want to learn more about quantum effects and their application in security and computing.

• You’re fascinated by electricity, energy and electronics.

• You want to reduce our carbon footprint by developing more efficient renewable energy solutions, rolling out smart energy grids, and designing hybrid and all-electric vehicles.

• You love the latest gadgets and want to design mobile phones, set-top boxes, music players and 3D TVs.

• You’re inquisitive and want to explore how things work, invent things, and design things that benefit society.

• You want to develop innovative real-time software solutions that run on embedded computers and processors.

• You’re passionate about medical electronics, and want to contribute to the development of life-saving instrumentation.

• The Internet amazes you and you want to learn more about terabit optical communications and gigabit wireless handsets.

• You’re creative and want to work in the digital media industry.

• You’re looking for generous sponsorship options, interesting summer placements, and exceptional employment prospects.

• With an electrical and electronic engineering degree you’ll have no trouble earning money. The technology is all-pervasive and present in every aspect of modern life.

• Electrical and electronic engineering is embedded in all other engineering disciplines (particularly mechanical and aerospace).

• The skills we teach are portable and starting salaries are up to £29k a year.

Study Electrical and Electronic Engineering

World's Best Universities: Engineering Top 100

TOP TEN

Massachusetts Institute of Technology (MIT) United States

Stanford University United States

University of California, Berkeley (UCB) United States

University of Cambridge United Kingdom

California Institute of Technology (Caltech) United States

Imperial College London United Kingdom

The University of Tokyo Japan

ETH Zurich (Swiss Federal Institute of Technology) Switzerland

University of Oxford United Kingdom

National University of Singapore (NUS) Singapore

OTHER,S

11 Tsinghua University China

12 Carnegie Mellon University (CMU) United States

13 Georgia Institute of Technology United States

14 University of Toronto Canada

15 University of California, Los Angeles (UCLA) United States

16 University of Illinois at Urbana-Champaign (UIUC) United States

17 Kyoto University Japan

18 Delft University of Technology (TU Delft) Netherlands

19 University of Michigan United States

20 Cornell University United States

21 Princeton University United States

22 Harvard University United States

23 Tokyo Institute of Technology Japan

24 KAIST - Korea Advanced Institute of Science & Technology South Korea

25 University of Manchester United Kingdom

26 Hong Kong University of Science and Technology (HKUST) Hong Kong

27 University of Texas at Austin (UT Austin) United States

28 Purdue University United Statess

29 McGill University Canada

30 University of British Columbia (UBC) Canada

31 École Polytechnique Fédérale de Lausanne (EPFL) Switzerland

32 University of Melbourne Australia

33 Peking University China

34 University of California, San Diego (UCSD) United States

35 École Polytechnique, ParisTech France

36 Technische Universität München (TUM) Germany

37 Nanyang Technological University (NTU) Singapore

38 Seoul National University (SNU) South Korea

39 University of Waterloo Canada

40 RWTH Aachen Germany

41 National Taiwan University (NTU) Taiwan

42 University of New South Wales (UNSW) Australia

43 Shanghai Jiao Tong University (SJTU) China

44 University of Sydney Australia

45 Australian National University (ANU) Australia

46 University of Edinburgh United Kingdom

47 Indian Institute of Technology Bombay (IITB) India

48 Technische Universität Berlin Germany

49 Universität Karlsruhe Germany

50 Eindhoven University of Technology (TU Eindhoven) Netherlands

51 UCL (University College London) United Kingdom

52 University of Hong Kong (HKU) Hong Kong

53 University of Southampton United Kingdom

54 Indian Institute of Technology Delhi (IITD) India

55 University of Auckland New Zealand

56 Columbia University United States

57 Technion - Israel Institute of Technology Israel

58 Monash University Australia

59 Osaka University Japan

60 University of Wisconsin-Madison United States

61 KTH, Royal Institute of Technology Sweden

62 University of Queensland (UQ) Australia

63 University of California, Santa Barbara (UCSB) United States

64 Indian Institute of Technology Kanpur (IITK) India

65 Politecnico di Milano Italy

66 University of Washington United States

67 National Tsing Hua University Taiwan

68 Indian Institute of Technology Madras (IITM) India

69 Technical University of Denmark Denmark

70 Hong Kong Polytechnic University Hong Kong

71 University of Science and Technology of China China

72 University of Pennsylvania (UPenn) United States

73 Northwestern University United States

74 University of Alberta Canada

75 Technische Universität Darmstadt Germany

76 Katholieke Universiteit Leuven Belgium

77 Chalmers University of Technology Sweden

78 École Normale Supérieure de Paris (ENS Paris) France

79 Zhejiang University China

80 University of Minnesota United States

81 Yale University United States

82 Virginia Polytechnic Institute (virginia Tech) United States

83 University of Bristol United Kingdom

84 Universität Stuttgart Germany

85 Chinese University of Hong Kong (CUHK) Hong Kong

86 University of Chicago United States

87 Pennsylvania State University (Penn State) United States

88 Johns Hopkins University United States

89 RMIT University Australia

90 Indian Institute of Technology Kharagpur (IITKGP) India

91 University of Birmingham United Kingdom

92 Texas A&M University United States

93 Bandung Institute of Technology (ITB) Indonesia

94 Tohoku University Japan

95 Universität Politecnica de Catalunya Spain

96 Lomonosov Moscow State University Russia

97 University of Maryland, College Park United States

98 Vienna University of Technology Austria

99 Trinity College Dublin Ireland

100 Politecnico di Torino Italy

Source www.usnews.com

Best University Of Engineering In Bangladesh

1 Bangladesh University of Engineering and Technology

2 Ahsanullah University of Science and Technology

3 United International University

4 American International University-Bangladesh

5 North South University

6 East West University

7 Shahjalal University of Science and Technology

8 Islamic University of Technology

9 Khulna University of Engineering and Technology

l0 Daffodil International University

11 Independent University, Bangladesh

12 Chittagong University of Engineering and Technology

13 BRAC University

14 Rajshahi University of Engineering & Technology

15 Khulna University

16 Dhaka University of Engineering & Technology, Gazipur

17 University of Information Technology & Sciences

18 The University of Asia Pacific

19 International Islamic University, Chittagong

20 International University of Business Agriculture and Technology

21 University of Liberal Arts Bangladesh

22 Noakhali Science and Technology University

BEST Electrical and Electronic Engineering University Of Bangladesh

1 Bangladesh University of Engineering and Technology

2 Ahsanullah University of Science and Technology

3 United International University

4 Khulna University of Engineering and Technology

5 Chittagong University of Engineering and Technology

6 Rajshahi University of Engineering & Technology

7 Dhaka University of Engineering & Technology, Gazipur

4 American International University-Bangladesh

Keep your property where you can see it

2011-04-06T23:12:00.000-07:00

Surveillance camera ensures your valuables aren't part of the vanishing act

A safe home is a happy one, but many off-the-shelf surveillance cameras are too expensive or simply impractical for home use. That's why designer Alberto Ricci Bitti created an automated and inexpensive surveillance camera that uses a flash card as recording media.

All the required functionalities fit inside a small 8-bit microcontroller and the design harnesses the potential of the ATmega32: almost every hardware component of the AVR is put to good use, resulting in a leaner, more cost-effective parts list. The camera only needs to be set up once and an IR remote and easy-to-use voice-prompt menu means this award-winning design will be the star of the show.

Witness Camera

Video surveillance systems have rapidly grown from being a specialized equipment for high-risk areas (like banks and airports), to the point of being standard facilities of most places open to the public. Nowadays, no shopping centre, office, industry can afford lacking one. In conjunction with a time-lapse video recorder, these little cameras play an active role discouraging theft and collecting evidences and precious information about the offenders.

Despite their huge commercial success, video surveillance recorders have had little impact on residential markets. No doubt they would be useful at home as well as they are at work: according to the Police, most home thieves go unpunished, so in a sense homeowners must help for themselves.

I have always wanted a video recording system protecting my house, but commercially available systems didn't persuade me. Let's see why.

Standard systems won't do.

Commercially available systems are not designed for home use, and unfortunately don't adapt well to the new role. Problems start with the time-lapse recorder, which is a special recorder capable of recording several days of slow-frame-rate video on an ordinary VHS tape or a big hard disk. Most units are solidly built and usually they worth their money, nonetheless my concept of reliability for home use is "install and forget", which doesn't match hard disks or tape heads spinning forever.

If the price tag and periodic functionality inspections are OK for you, there is always the problem of placement. You need a out-of-sight place, spacious enough to accommodate the recorder and the video display, because images can only be inspected using the original recorder.

Another issue differentiating between commercial and residential systems is the way you run the wires from the camera to the recorder. For shops and offices you can easily pass the cable under the floor or over the ceiling, but if you live in a old brick house like me, you simply can't do it without cutting the walls. You can try RF-linked cameras, if you don't care wiping out all WiFi networks in your neighbourhood (and you are not concerned about exposing your privacy). Alternatively, you can use good WiFi cameras that by definition preserve the network, with only drawback of consuming most of the bandwidth for themselves...

My tailored solution.

The Witness Camera is a combination of a VGA CMOS camera, a passive-infrared movement sensor, a 1 GB SD-card (or bigger), and an AVR Mega32 microcontroller implementing a solid-state time-lapse recorder. It is a compact, complete, self-contained surveillance system designed with home users in mind. It can be installed in minutes wherever there is a mains plug, and it is affordable because of it is built using an handful of inexpensive parts.

For most typical domestic environments, it can store more than one month of images at a maximum rate of a colour picture every 2 seconds (320x200 pixels, comparable to VHS-CCTV recorders), or 3 seconds (VGA, 640x480 pixels). Recording starts automatically upon detecting a movement. Alternatively you can set a timer, or supply an external trigger, and even do continuous recording.

You only need to setup the camera once. An infrared remote control and voice-prompt menus allow easy operation, even when the camera is concealed or installed in places like ceiling corners.

When the card is full, new images replace automatically older ones, so you get always the most recent snapshots. You won't even notice the system is working; there are no moving parts, no fans, no electrical power wasted.

In the (unfortunate) case you need to investigate the images, just take off the card from the camera and put it on any PC or laptop with an SD-card slot. Specialized software is not required: the Witnesscam records its files using a standard file system (FAT16 or FAT32) and image compression format (JPEG). Retrieval is immediate as the camera sorts the pictures in folders according by date and time.

How it works.

The Witness Camera operation is conceptually simple, but involves many ingredients. Some are physical components, the others are software blocks. To make things clear, I will introduce them gradually, according to the operating mode.

The most important hardware component is the ITC328 camera module. It consists of a VGA (640x480) CMOS colour sensor and a JPEG-compression chip. The compression engine includes a serial interface at 3.3V levels that can be connected directly to a microcontroller's UART. Issuing the appropriate commands you can take snapshots as JPEG-compressed byte streams. The camera comes in a handy module with everything including the lens, and a 4-pole connector for power and data.

The most important software component is the AVR-DOS file system. It is a library for driving mass storage devices, like SD and MMC cards, CompactFlash, and even hard disks connected to the AVR microcontroller. It provides an high-level programming interface for accessing disks formatted according to FAT16 or FAT32 specifications, which means its files are directly compatible with PCs. By linking AVR-DOS to your program you can create and open files, write and read data, create and change directories with simple commands, like you would do on a PC. Restricting read/write access to one file at a time, the FLASH and RAM footprints are minimal (8kB and 1.3kB), making it possible to use a small 8-bit AVR device like the Mega32 for tasks usually accomplished by 16- or even 32-bit processors.

These two blocks are the foundation and starting point of the Witness Camera design. With the aid of the simplified block diagram of Figure 1, let's see how these block interoperate during normal operation as a time-lapse recorder.

This diagram introduces a second hardware block, the PIR (Passive Infra-Red) movement sensor model ITM256. This module can sense people up to 5 meters/16 feet away, by measuring changes in the infrared radiation caused by human body temperature. It is a cheap mass-production part from the burglar alarm market, including a Nicera RE200B thermopile and a KC778B companion chip in dice form, under the familiar epoxy blob. A Fresnel lens with an angle of 60º snaps in the PCB, which connects to the outside world by means of a short 3-pole cable (power, ground and signal).

The PIR triggers a software block, the recorder, which is in charge of deciding if and how many pictures to take according to its trigger inputs and operating mode. The recorder controls the camera driver (another software module) in order to get the JPEG byte stream. The real-time clock is an hardware feature of the AVR controller, and the recorder uses it both for time-stamping the JPEG files with current date and time, and as an interval timer if time-lapse photography mode is selected. After time-stamping, the recorder hands over picture data to the file system, which stores it permanently on the SD-card.

Having a file system in place opens up many possibilities to the world 8-bit microcontrollers. Once you try it, it's hard to go back. The capability of accessing huge data files is exploited also in the other operating mode of the Witnesscam, the setup mode.

During setup the user interacts by means of an infrared remote control (I have used an off-the-shelf universal remote), and the Witnesscam responds with voice prompts. The prompts guide the user through the editing of all the operating parameters (date, time, recording mode, picture resolution, number of frames to take each time the sensor triggers...).

The voice menu block is the software module running the user interface. It takes the pulse train from the infrared receiver as input, and after decoding it uses it to edit the settings from AVR's non volatile memory. During this process, it invokes the speech synthesizer module, which provides the primitives needed to compose and play the messages.

The speech synthesizer takes advantage from the existing mass storage capabilities, using the file system in read mode. The flash disk must be prepared in advance with a special set of files with audio samples for each word or status messages to be pronounced, e.g. the file "15.PCM" stores the waveform samples for the word "fifteen". Reconstructing the audio signal is then a matter of opening the file and sending the samples to the AVR PWM feature.

Samples compression is unnecessary. Years ago, devoting more than one megabyte of flash for this purpose would have been regarded as extravagant opulence, but today this figure represents about 0.1% of flash disk capacity! So this technique is cheaper than an LCD display, and ways more effective, because it's expected that the camera is concealed or placed out-of-the-way.

The complete picture.

The complete block diagram is the sum of the two previous diagrams plus some extra details. The software modules are drawn inside the AVR Mega32 body. For ease of reference, the relevant source file names are given in italics.

The complete block diagram isn't trivial. It includes both hardware parts and software-only objects and libraries (file names in italics). The Mega32 is a perfect fit for this design, as almost all of its features are used.

This chart shows the file system exploded into its constituents: the AVR-DOS library, the underlying SD-MMC software driver which takes care of low-level access to the physical media, and the SD-card itself. The card talks to the AVR via the hardware SPI interface, which is notably fast in Mega devices.

There is a new file manager layer (file archive.bas) mediating between the recorder and the AVR-DOS file system. Its purpose is to provide helper functions like determining the oldest files in the archive, deleting unused stuff to make room for new images, and creating an orderly set of directories and files to archive the pictures according to the time stamp.

Another added functionality, introduced in order to preserve disk integrity, is power monitoring. The system must cease any disk write in case of problems. It measures both main and battery voltages using the 10-bit AD converter of the AVR.

The remaining functions are not essential for the Witnesscam to work, but make development and use much easier. With the PC debug port you can log system operations messages (disk size and free space, JPG file size, read and write file access details, remote control codes received) for diagnostic purposes - or just for the pleasure of watching the internal clockwork in action.. I created the port bit-banging an I/O pin, a technique that works perfectly for low baud rates (9600) and allows setting of signal polarity. That is, you can connect the AVR pin straight to the RX pin on PC serial port, without any interface logic (a priceless trick for debug).

The AVR can drive LEDs from all of its general purpose I/O pins. I have provided two status indicators on the front panel. They are useful to verify the PIR sensor range and to check if disk is actually recording.

Notably, I have introduced two extra LEDs inside the box, next to the SD-card slot. I call this the "disk semaphore": when the green light is on, it's safe to extract or insert the SD-card from its slot. A red light signals that a disk operation is in progress, and you must wait before touching the SD-card. A simple algorithm inside the main recording loop determines what light to put on based on the status of the recorder, the card detect switch from the SD-card receptacle, and the lid detector switch that notifies the system when the camera case is opened.

BASIC instinct.

The most peculiar aspect of this design is that the firmware is written in BASIC. I'm a strong advocate of using C for embedded systems, and I use routinely the excellent GCC compiler for AVR development on PC and Linux platforms. But at the time I was waiting for the samples of the camera to arrive, I was asked to select a BASIC compiler and IDE for an educational board my company was developing.

BASCOM-AVR from MCS electronics is a stable, popular product with a rock-solid user base, and a syntax similar to Visual Basic. The IDE installs with lots of examples, and you don't need anything else to make your applications. Actually, the IDE integrates all sorts of accessories including a simulator, a chip programmer and (nice touch) a serial terminal.

While browsing the online help, my attention was caught by the AVR-DOS library supplied with the package. The help includes a schematic for wiring an SD or MMC card to the SPI, and a 3-line-long code snippet for writing a text file:

open "README.TXT" for output as #1

print #1, "HALLO FILE!"

close #1

I couldn't resist trying it. I grabbed an SD-card from the nearest photo camera, the Atmel's STK300 evaluation board and a soldering iron. A few minutes later, Windows Notepad running on a 32-bit, 3 GHz machine was opening a file written by an 8-bit, 8 MHz AVR microcontroller. I was hooked.

BASCOM does a good work at simplifying hardware access. For small applications, it's a time saver. Do you need a real time clock? Just tell the compiler, and he will do the hard work of making timer interrupt code specific to the AVR flavour you selected. Do you need buffered serial I/O? Just select the buffer size and baud rate. The list of supported features is long - RC5 infrared remote control, ADC readout, timers and PWM setup, to name a few that were useful for the Witnesscam project. But also graphic and text LCD, 1-wire devices, SPI and I2C busses, PS2 mice, AT keyboards, and even a TCP/IP stack.

On the other extreme, as the complexity of your application increases, you will miss C type checking, aggregate types and support for modularity. Also, BASCOM error massages are obscure when not misleading, and lacking of automatic type conversions and true expression handling is an unnecessary pain. My advice is to stay on C if you expect to develop more than 64 kB of code; for smaller designs, like this one, it makes sense to opt for BASIC if you are exploiting most of the built-in features it offers. BASCOM supports structured programming, and with a bit of discipline you can write code as organized as you can do in C. See the sources for my best attempt at doing it!

Filled to capacity

Keeping the disc filled to capacity, but not overfull, was a challenging problem.

In theory you can get disk occupation calling diskFree(), find the oldest file in the disk and delete it. In practice it turns out that both operations are time-consuming, so you must avoid them as much as possible. To complicate matters, file size isn't constant. It depends on the scene and how it gets compressed by the JPEG algorithm. It depends also on the time of acquisition, because storing a picture file may require creating new directories (hence more disk space) each time the year, month, day, or hour change. And users are free to select a different resolution or recording mode at any time, changing the space required to accommodate new files.

I developed an heuristics based on common-sense rules:

When the disk is only partially full, it is sufficient to check disk occupation only every now and then, and all files can be conserved without problems.

As disk occupation increases, the amount of space left need to be checked more frequently, and it's wise to start deleting some files. As deleting files burns precious machine cycles, it's preferable to do it when the camera is idle, i.e. recording isn't triggered.

Should disk occupation reach its limits, disk occupation checks must be performed frequently. Deletion of oldest files must be performed anyway, even if the processor needs resources for recording, because of the risk of getting out of disk space.

Careful section of the value for deleteWhenIdle and cleanupInterval improves recorder's performance in all but continuous recording modes, because all erasing is performed when there is nothing else to do. If you feel 1000 pictures is a large number, consider it represent a negligible percentage of full disk capacity. It takes time to get accustomed to the Gigabyte Age!

The flow chart in Figure 4 should shed some light on how the heuristics works. Experimentation in my house as PIR-triggered recorder resulted in all file erases performed during idle, calling diskFree()at most every 30 minutes.

Speech preparation.

The Witnesscam speech synthesizer plays a set of speech files to build its messages. You can record the files with your own voice if you want, but I was reluctant doing this, so I used computer-generated speech instead.

I would like to tank the people at AT&T Research Laboratories for giving me the permission of using samples from their Natural Voices system for this contest. Those unfamiliar with this technology can test their fantastic software online (http://www.research.att.com/~ttsweb/tts/), typing-in any text and listening for a warm, natural voice reading it.

I used the AT&T online demo tool to download a set of .WAV files with the words of interest. I selected a male voice (Mike) in order to reduce the content of high frequencies as possible. The Witnesscam dynamic range is 8 bit, and sample rate is 11,250 Hz, so I used a sound editing program (Cool Edit Pro) for down-sampling. I compressed the voice waveforms using the dynamic compressor tool in order to compensate for the reduced bit resolution (AT&T audio files are 16-bit). Then, I normalized the amplitudes, and saved each speech segment in a separate file as 8-bit "unsigned" samples - that is, raw numbers where silence corresponds to a value of 128.

At run time, the Witnesscam uses the file name to select the files to play. It expects to find them under a common folder named "speech". Sound playback technique is brutally tricky. The samples are banged straight to the PWM without buffering, the only timing coming from a busy-wait loop. Ironically, the unpredictable delays due to disk access add a pleasant chorus-like effect, making the voice warmer and fuller.

The circuit amplifying the PWM signal is even more brutal, using just one transistor and trusting the speaker elastic properties for filtering higher frequencies and moving the cone back to the positive direction. These shortcuts limit the kind of speaker to use: if it's too small, the Nyquist products will be audible, if it's too large, it won't jump back in time for the next audio peak. I have experimented with various sizes from my junk box, and found that a 75mm/3" speaker works well - surprisingly well. A clear sign that speech is like no other sound, because the brain is capable to reconstruct the voice from very little information.

Circuit implementation.

The final circuit of the Witness camera works out the details of interfacing the modules introduced by the block diagram, and supplying power as appropriate. The circuit develops around the AT Mega 32, and most interfacing resolves to straight connections, as all AVR I/O pins provide programmable pull-ups and respectable output current. One notable exception is the PIR movement sensor (Intertec's ITM256), which is a 5V part (opposed to the rest of the circuit that works at 3.3V), and needs an independent power regulator (IC3, an LM2936-Z5 low-dropout, low quiescent current regulator from National). A separate regulator is beneficial in this case, as it provides extra power decoupling for some very sensitive analog amplification contained on the PIR module. A series resistor on the PIR output is an inexpensive way to adapt its 5V output to the 3.3V input level of the AVR.

The camera module (Intertec ITCM328) connects to the UART RX and TX pins. Communication runs at 115200 baud, thus I selected a 7.3728 MHz crystal for exact bit timing. Don't replace it with the more common 8MHz as the camera module is picky about baud rates. The SD-CARD connects directly to the SPI port pins. The card connector is a Yamaichi FPS009-3202. I like its space-saving outline, with most of its pin placed inside its body instead of sticking out.

The connector features also extra signals indicating card insertion status and the position of the write-protect tab of the card. I routed them to two spare I/O pins (internal pull-ups enabled). A different kind of switch, the micro switch detecting when the lid is opened, and the external trigger switch connect in the same way to the AVR.

However, I selected one of the three AVR interrupt pins for the external trigger, in order to capture and flag automatically any transition. The same applies to the PIR input (think of it as an "internal" trigger) and the remote control input.

The latter pin comes from a Vishay TSOP34836 infrared receiver IC. This inexpensive part is mass produced for the consumer market (TV, VCRs, DVDs...) and is tuned for 36kHz infrared bursts (like the RC5 encoding required by the Witnesscam). You can replace it with similar parts from other manufactures; I selected it for its immunity to false triggers, which improves Witnesscam's overall performance.

As regards the outputs, four LEDs showing device status take half of the port A. A spare bit on port C drives the relay output by means of the typical transistor & diode network. I used a BC847 and 1N4001.

As previously detailed while describing the audio subsystem, the same conventional circuit drives the output speaker in an unorthodox way. I tried it for fun, and it worked so good that I didn't change it.

Another unorthodox section is the serial port built around port C, bit 5 of the AVR. Being a software implementation, its polarity is reversed compared to an hardware UART, so the usual additional polarity inversion circuitry is not required. You can connect it to a PC running a serial terminal program for debug or troubleshooting: connections to the PC DB9 pin are PC-TX to DB9-PIN3, PC-GND to DB9-PIN5.

Admittedly, this circuit doesn't meet RS232 specifications (no negative voltages, just 3.3V swing, imperfect timing during interrupts limiting speed to 9600 baud), nonetheless it's a zero-cost solution that does its job.

I've been less parsimonious with the power supply: it's easy to overlook power supply issues. The camera and the flash disk have an impulsive behavior, consuming almost nothing when not in use and drawing intense bursts when writing or compressing an image. Thus I provided both a 100 µF electrolytic and a 0.1 µF ceramic capacitor for most parts. These caps are outlined in a separate section of the schematic diagram, take care to place the capacitors near to their respective owners.

DC power comes from a wall-wart adaptor and a battery pack. The batteries keep clock running (see the 32.768 kHz crystal), while ensuring completion of disk operations during power outages. A 15V varistor cuts power spikes, and diodes D1 and D2 mix the power sources prior to power regulators. The 1N5822 are Shottcky diodes in order to optimize the voltage drop. The 3.3V regulator is a LM1117-3.3 (National Semiconductor) low-dropout regulator.

The circuit monitors its own power to safeguard disk integrity. Two identical divider networks for battery power (R3-R4-C5), and mixed power (R7-R8-C8), reduce voltages to safe levels suitable for ADC pins. Don't omit the capacitors that smooth the measurements and provide a charge tank for sampling.

Almost all of the parts (with the notable exception of the camera, see the FAQ for details) can be obtained from RS Components: here are the part numbers:

Quantity	RS Part #	Part description
1	267-6930	8 ohm, 3 inch diameter loudspeaker
1	652-7494	Diode (LL4148 or 1N4001)
1	434-8104	100 nF ceramic capacitor (1206 case)
1	519-4059	100uF/25V electrolytic capacitor (TPH)
1	264-4040	15...22pF ceramic capcitor (1206 size)
1	464-8909	15Vdc transient suppressor
1	132-494	1K resistor for LED
1	150-710	microswitch, lever actuated
1	478-9268	32.768kHz CFPX-56 watch crystal
1	226-1695	7.3728 MHz crystal
1	237-647	Yamaichi FPS009-3001-BL SD/MMC card connector
1	533-5604	Ultra low dropout voltage regulator, TO92 case
1	533-9527	LM1117T-3.3 fixed voltage regulator
1	377-9664	Two pole toggle switch
1	461-3739	1000 ohm, 0.25W, 5% resistor (size 1206)
1	461-3723	100 ohm, 0.25W, 5% resistor (size 1206)
1	461-3745	10 kiloohm, 0.25W, 5% resistor (size 1206)
1	461-3751	100 kiloohm, 0.25W, 5% resistor (size 1206)
1	223-2300	2.2 kiloohm, 0.25W, 5% resistor (size 1206)
1	223-2085	50 ohm, 0.25W, 5% resistor (size 1206)
1	223-2186	330, 0.25W, 5% resistor (size 1206)
1	484-2252	BC817 transistor (SOT123 case)
1	826-515	Red LED, 3 mm
1	180-8502	Green LED, 3 mm
1	351-825	Subminiature relay, 10V coil
1	482-193	10-way box connector for programming
1	628-1485	Atmel AtMega32 AVR processor

CIRCUIT

What Is Electronics Technology

2011-03-13T06:33:00.000-07:00

Electronic devices are an integral component of our society. Industrial control and automation systems; communication networks; entertainment systems; wireless communication devices; medical technology devices; home appliances systems; satellite communications; public emergency safety systems; and private security systems all utilize electronics technology.

The Electronics Technology Program offers students a broad-based foundation in electricity, electronics, semiconductors, digital logic, control systems, robotics, instrumentation, data communications, and wireless technologies.