Techsi

2020-09-02T02:59:00.001-07:00

Original Xiaomi Pro 300M WiFi Router Amplifier Repeater Signal Cover Extender Roteador 2 Wireless Router Repetidor Mi repeater

Please note:

1. The product comes with the plug is the American standard 2. For European, English and Australian plugs. 1) If you buy a non-American product, we will send the corresponding European, English and Australian plugs in the package, noting that they are not original. 2) When using, please use this plug to connect the American regulations of the amplifier.

operating manual

About Xiaomi WiFi Amplifier Pro

Xiaomi WiFi Amplifier Pro is a device that is used to extend the WiFi signal and can expand the existing network signals in the home.

Indicator light Blue light is on (normal work)

Blue flashing (upgrading)

Yellow light is on (starting)

Yellow flashing (waiting for initialization)

Red flashing (hardware failure)

Reset hole Press for more than 5 seconds to restore factory settings

Install

1.Place the amplifier close to the router, wait for the yellow light to flash after power connection.

2.Scan the QR code, or go to “Mi Store” and “Apple Store” to download the Mi App. Open the "Mi home" app, or click "+" to add Xiaomi WiFi Amplifier Pro and follow the prompts.

3.After setting successful, the blue light is on, the amplifier can moved to another location without operate again.

LAN Ports: 0

Main Features:

● Two powerful high-gain external antennas give wider coverage and better performance
● Wireless function, make your wireless coverage larger
● Compatible with other brands router
● Transmission rate: 300Mbps
● Support up to 64 devices to fulfill the needs of the whole family
● Manage your network settings easily with the Xiaomi Mi WiFi APP
● This amplifier will upgrade automatically without any setting
● Plug and play, easy to use

Compatible with most routers

3 stages make your wireless coverage large.

Follow the instruction and scan QR codes with your phone.

One router can work with several our amplifier

2 powerful high-gain external anternnas(2dBi) give wider coverage and better performance when lots of devices are connected, making it ideal even for a large home

Support up to 64 devices to fulfill the needs

of the whole family (24 devices are suggested)

Network fault detection, to protect your network use

When the network has problem, Xiaomi App will remind you, and provide you with solution, accurately check the current signal strength and link status, to solve the problem.

Plug-in design, rechargeable from a conventional wall outlet

This amplifier will upgrade automatically without any settting

Purchase note

1. after receiving the parcel in 7 days, we can accept to return back and refund without any reason;More than 7 days, we supply warranty to repair or a replacement;

2. when you receive the parcel, in order to protect your interests, please be sure to shoot video when opening the parcel, so if the item is lost or the packaging appearance is damaged, the buyer can provide the evidence on time.If can't provide the opening parcel video , we will not undertake any responsibility for it;

3. about the outer packing, we guarantee the products are 100% original , but manufacturer have right to amend it ,so appearance and packaging design may change without prior notice, at the same time we also will not undertake any responsibility;

4. if you place the order, indicate that you agree to the above terms and conditions.

Kind Tips:

1. Color

Display and light of shoot will affect the color of the products, pictures for reference only, subject to our available products

2. Surface Scratch

All of Xiaomi products need to be tested before sent out , surface scratch is normal

3. Weight

Based on the express company and our weight result before sent

4. Appearance of Products

pictures for reference only, subject to our available products

5. Package Broken

Long international shipping will damage and crush the package , if you found there is unpacking signs, please do not sign for . Outer Package in good condition, but the product retail package by extrusion deformation, but does not affect the product use, is normal.

6. Package

We guarantee the products are 100% original , but manufacturer have right to amend it ,so appearance and packaging design may change without prior notice, at the same time we also will not undertake any responsibility

7. Authorization

We are Xiaomi official authorized seller, All of our products are original , can be checked on Xiaomi official website

8. Russian Buyer

Russian policy , please confirm your full name .

Easily remove watermark of Windows 8 Consumer preview

2012-03-24T00:54:00.001-07:00

Microsoft released "Windows 8 Consumer preview".Which is a preview of the Microsoft's next version of Operating system after "windows 7".

Download Windows 8 from here ( If you haven't done-it is totally free )

This version of Windows has targeted mainly on mobile computing and it will be very handy in Laptops,Tabs and Smart-phones in future.

There is a watermark on the desktop after instaling the Windows 8 Consumer Preview.Which can be seen on the right bottom of the Windows 8 desktop.
I am giving you a small software, which removes the watermark very easily.You may not need any advance computer knowledge.Just download the software and run it.

Here is the link to download ,

Click here to download(556kB)

Run this software. you may see a interface like this.

Tick "remove all watermarks" at the top and click on Apply new settings.Wait few time until this finishes the operation.

Here you go..Enjoy windows 8

2012-03-19T06:31:00.000-07:00

Dear All,

Please visit www.funcom.info for complete set of articles.This is a website dedicated for sharing knowledge of Telecommunication engineering.

Difficulties in Radio Interface and Solutions to Them

2012-03-04T20:48:00.002-08:00

a) Path Loss

Increase Power

Path loss if fading the transmitting or receiving signals with the distance increases. Increasing the transmit power is a solution for this problem. But there are limitations in transmit power.

Idle mode cell changing

To avoid receiving strength failures, MS always measure the receiving signal strength from connected cells and its neighboring cells. If a neighboring cell’s signal strength is higher and MS is in idle mode then MS listen to its BCCH and make connection to that cell’s BTS.

Handover

However when MS is in active mode (In a call) then this procedure is bit of tricky since traffic channels should be changed. Handovers are controlled by the BSC according to the hand over definitions in the site.

b) Shadowing

Shadowing is path failures due to obstacles in the air interface. This is unavoidable but it can be minimized by proper planning.

c) Multipath Fading

Multipath fading occurs due to existence of more than one receiving paths of signal.

Rayleigh fading

These signals might be a reflection from a space and it is identical to the original signal and only a phase changes are there. This is also called ghost signals. There are some ghost cancellation technologies to avoid the problem.

Time Dispersion

Time Dispersion is also a multipath fading but due to reflecting from distance bodies there may be time differences in signals.

d) Time Alignment

A large distance between the MS and the BTS causes time alignment. Effectively, the signal cannot travel over the large distance within the given time. So the part of a particular timeslot’s signal may come in next timeslot’s time. To avoid this problem a special time adjustment is used in air interface. This is called the Timing Advance (TA). It instructs MS to transmit certain time before the actual time it transmits. BSC calculate and transmits the TA to the MS.

e) Capacity and Frequency Limitations

Allocating same set of frequencies in neighboring cells is not applicable with conventional GSM. But with the growth of the network need of more capacity raised as a big problem. Frequency hopping techniques were introduced to overcome this problem.

GSM - Global System for Mobile Communications

2011-11-29T06:35:00.001-08:00

GSM is widely used network system used in the World.It uses TDMA and FDMA as access technologies.

Frequency Allocation and Physical Channels

From 890 MHz to 915 MHz is used for uplink (from MS to BTS) and 935 MHz to 960 MHz is used for downlink (from BTS to MS). Both uplink and downlink has a bandwidth of 25 MHz each. That 25 MHz bandwidth is divided in to 124 carriers. Each carrier is time divided in to TDMA frames which are consisted of 8 time slots. A one time slot can be considered as a “channel”, each timeslot consists of a usable part of 114 bits and a training sequence of 26 bits. This training sequence is very important as it is used by the Mobile to identify the timeslot number.

In a GSM Base Transceiver Station, up to 12 transceiver units can be used to serve for a single cell. (That is for latest BTS). Each transceiver can handle one carrier. (I.e.8 channels). That one channel can act as a traffic channel for a single user. Normally time slot 0 and time slot 1 are used for signaling between the mobile and the BTS. Since signaling doesn’t need data rate as that for traffic, we can divide the signaling channels in to more logical channels.

Channel Concept in GSM

One carrier in GSM form 8 TDMA channels and these channels can be used to transmit and receive signaling, voice or data. There are special channels defined in GSM air interface for signaling purposes. These are called logical channels. Sometimes they exist in the same physical channel but logically separated. Some of the important logical channels are listed below.

· Broadcast Channels (BCH) (Down-link Only)

Ø Frequency Correction Channel (FCCH) - used for frequency correction of MS

Ø Synchronization Channel (SCH) - carries information on the TDMA frame number and the Base Station Identity Code (BSIC) of the BTS

Ø Broadcast Control CHannel (BCCH) - Broadcasts cell specific information to the MS

· Common control channels

Ø Paging Channel (PCH) - BTS Transmits a paging message to indicate an incoming call or short message. The paging message contains the identity number of the mobile subscriber that the network wishes to contact. At certain time intervals the MS listens to the PCH. If it identifies its own mobile subscriber identity number on the PCH, it will respond.

Ø Random Access Channel (RACH) – used on uplink by MS to request a SDCCH for call setup, locations update, SMS or answers paging message.

Ø Access Grant Channel (AGCH) – Used on downlink to allocate a SDCCH (signaling) or a TCH to a MS.

· Dedicated Control Channels (DCCH)

Ø Stand alone Dedicated Control Channel (SDCCH) - used for system signaling during call set-up or registration. Uplink and downlink as well as transmission of SMSs (in idle mode) are done in this logical channel.

Ø Slow Associated Control Channel (SACCH) – control channel associated with a TCH or an SDCCH. Measurement Reports from the MS to the BTS are sent on the up-link. On the down-link the MS receives information from the BTS what transmitting power to use. In addition, the SACCH is used for the transmission of short text messages in call connected (busy) mode.

Ø Fast Associated Control Channel (FACCH) – Control channel associated with a TCH. Also referred to as Fast Associated Signaling (FAS), the FACCH works in stealing mode. That is, 20 ms of speech is replaced by a control message. It is used during handover, as SACCH signaling is not fast enough. Used on up-link and down-link

· Traffic Channels (TCH)

Traffic channels are used to transmit voice traffic. They caries no signaling and MS tuned in to these TCHs according to the information given through SDCCH.

· Packet Data Channels (PDCH)

PDCH are used transmit packet data traffic. They are used in GPRS and EDGE.

These logical channels are mapped into the physical channels in groups. For example BCH can be set at timeslot 0 of carrier 0. Likewise others can be mapped to the physical channels in GSM air interface.Others are defined as TCH channels and PDCHs are dynamically allocated according to the request.

Data Coding, Encryption and Data Integrity Techniques in GSM

As a digital communication system GSM has to convert analog voice signals to digital data streams. Other than normal A/D conversion GSM uses speech coding technique which will transform analog voice to digital stream with bit rate 13 Kbits/s per subscriber.

After speech cording channel coding take place. Channel coding in GSM uses the 260 bits from speech coding as input to channel coding and outputs 456 encoded bits. This will assure the data integrity on air interface. Channel coding took place in hierarchical way such that its input is divided into three blocks and do the coding to them. They are 50 very important bits, 132 important bits and 78 not so important bits. These blocks are coded in different levels so that important bits may go through the air interface very safely.

After channel coding , two stages of interleaving takes place. Single step of interleaving divide a single information packet in to four transmitting packets . Ultimately lost of one packet at air interface will only affect 12.5% of information lost. Then the ciphering takes place to encode the burst so that it cannot be interpreted by any other device than the intended receiver. The ciphering algorithm in GSM is called the A5 algorithm. Then burst formatting include some extra information such as the 26 training sequence bits, 2 flag bits and 6 tail bits to the packet and modulate the digital data with GMSK (gaussian-minimum-shift-keying) to transmit.

Access Networks- Mobile

2011-11-29T06:10:00.001-08:00

The Access Network is defined as the setting up the communication between end user terminal and the transmission Network.

The bandwidth allocated for a mobile telecom operator is a very expensive resource. Therefore the company must occupy the frequencies very efficiently.

The widely used moble technology is GSM(Global System for Mobile Communications).GSM networks operate in a number of different carrier frequency ranges.GSM 900MHZ Band is used, when increasing the coverage. Typically GSM 900MHz can cover wide area compared with 1800MHz band.When the frequency getting higher and higher air lose increases. Sometimes, 900 Band will not enough to deliver high customer demand ,in that case we have to use 1800 band to increase the capacity.

We are using different access technologies to address each user privately with the limited resource frequencies.TDMA,FDMA and CDMA are the access technologies which allow to share the limited bandwidth with subscribers.

FDMA (Frequency Division Multiple Access) In FDMA, signals from various users are assigned to various frequencies. (Just as in an analog system) Cross talk between adjacent channel users is avoided by maintaining a frequency guard band between them. Advantages of FDMA are that the capacity increases can be done by reducing the information rate and efficient digital codes. Also the technological advances required for implementing the system are simple
TDMA (Time Division Multiple Access) This is the access method used in GSM. In a TDMA system data from each user is conveyed in time intervals called slots. Several slots make up a frame. Each slot is made up of a preamble plus information bits addressed to various (mobile) stations. The functions of the preamble are to provide identification and incidental information and to allow synchronization of the slot at the intended receiver. However it is a disadvantage that TDMA requires a large amount of signal processing for matched filtering and correlation detection for synchronization with a time slot.

CDMA (Code Division Multiple Access) The primary advantage of CDMA is its ability to tolerate a fair amount of interfering signals compared to FDMA and TDMA. So the problems of frequency band assignment and adjacent channel interference is greatly reduced. With CDMA, adjacent micro cells share the same frequencies whereas with FDMA/TDMA it is not feasible for adjacent micro cells to share the same frequencies because of interference.

I will discuss about these access technologies in later posts.

A New Set of Articles

2011-10-05T05:47:00.000-07:00

I am extremely sorry that i couldn't write any thing for a long period.But I thought to start bloging again about technical stuffs.So I thought to write a complete set of articles about telecommunication.Wait for articles

Free web hosting

2009-12-28T08:34:00.000-08:00

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2009-10-22T05:39:00.001-07:00

Importance of the parallel operation of transformers

Transformers are placed in parallel by electric utilities when they want to provide a 'stronger' voltage source and will result in higher available fault current that can be delivered downstream. Usually the utility transformer can serve its own load but two are put together to achieve with a ties primary and secondary bus to 'stiffen' the voltage to ride through system load changes. Because here we have more transformers connected in parallel. So even if, one of the transformers gets into a fault or is taken out for maintenance or repair, the load can continued to be serviced. Therefore by this we can reduce the spare capacity also.

Before two or more transformers connected in parallel and to share a common load satisfactorily, there are some conditions to be satisfied. Those are the voltage ratio (turns ratio) and the per unit impedance of each machine on its own base must be the same. When two transformers are connected in parallel, the impedances of the transformers must match (within 10%) to divide the load approximately equally between the two transformers or to divide the load according to the rating of each transformer. If the transformers to be connected in parallel are equipped with load tap changing windings, then the impedances for each of the tap changer positions must match. If these conditions are not met, then one of the transformers could conceivably carry a continuous overload, resulting in overheating.

Also the polarity must be the same, so that there is no circulating current between the transformers.
The polarity of connection in the case of single phase transformers can be either same or opposite. Inside the loop formed by the two secondary the resulting voltage must be zero. If wrong polarity is chosen the two voltages get added and short circuit results. The phase sequence must be the same and no phase difference must exist between the voltages of the two transformers. When these requirements are satisfying we can have a good parallel operation of transformers which is very useful and favourable in practice.

Generally, application of parallel transformers allows achieving the following benefits:

Reducing the total capacity of electrical transformers (as compared to separate their work). The decrease of total installed capacity is reached:

by lowering the overall demand load to the diversity of loads connected to different transformers
by using a higher load rate of parallel transformers
less required backup in case of electrical transformer failure

2) Reduction of electricity losses in electrical transformers due to a possible disconnection of unloaded transformers

3) Improving the power quality due to the stable level of short circuit current throughout the network

4) Increasing the reliability of operation of protective devices in the case of phase-to-earth short circuits in the network.

5) Possibility of placing electrical transformers in operation phase-by-phase

Importance of the parallel operation of transformers

2009-10-22T05:37:00.000-07:00

Transformers are placed in parallel by electric utilities when they want to provide a ‘stronger’ voltage source and will result in higher available fault current that can be delivered downstream. Usually the utility transformer can serve its own load but two are put together to achieve with a ties primary and secondary bus to ‘stiffen’ the voltage to ride through system load changes. Because here we have more transformers connected in parallel. So even if, one of the transformers gets into a fault or is taken out for maintenance or repair, the load can continued to be serviced. Therefore by this we can reduce the spare capacity also.

Also the polarity must be the same, so that there is no circulating current between the transformers. The polarity of connection in the case of single phase transformers can be either same or opposite. Inside the loop formed by the two secondary the resulting voltage must be zero. If wrong polarity is chosen the two voltages get added and short circuit results. The phase sequence must be the same and no phase difference must exist between the voltages of the two transformers. When these requirements are satisfying we can have a good parallel operation of transformers which is very useful and favourable in practice.

Generally, application of parallel transformers allows achieving the following benefits:

1) Reducing the total capacity of electrical transformers (as compared to separate their work). The decrease of total installed capacity is reached:

· by lowering the overall demand load to the diversity of loads connected to different transformers

· by using a higher load rate of parallel transformers

· less required backup in case of electrical transformer failure

2) Reduction of electricity losses in electrical transformers due to a possible disconnection of unloaded transformers

3) Improving the power quality due to the stable level of short circuit current throughout the network

4) Increasing the reliability of operation of protective devices in the case of phase-to-earth short circuits in the network.

5) Possibility of placing electrical transformers in operation phase-by-phase

Windows 7 released

2009-10-22T05:29:00.000-07:00

Windows 7 finally released today.The interest for the new OS from Microsoft has been huge, making Windows 7 the biggest pre-order item in the history of Amazon UK and a perpetual trending topic on Twitter. The reactions from users and reviewers have been mostly positive, but after the lukewarm it’s-ok-but-why-should-switch-from-WinXP attempt that was Vista, the fact that people can’t wait to get their hands on Windows 7 is hardly a surprise.
And, for the most part, it’s true. Annoying security features such as UAC have been fixed in Windows 7 (you can now manually set its annoyance level), the system feels speedier and more responsive (although it really isn’t that much faster when you actually measure it (for example, boot time on both systems is pretty much the same on my computer), but it feels that way, and it’s all that matters), compatibility issues have been fixed. In short, it’s more of a really, really good service pack for Vista than a new OS, but it’s definitely enough to switch from the eight year old Windows XP.
If you’re interested in making the switch, the price is $319 for Windows 7 Ultimate, and $299 for the Professional version ($219 and $199 for the upgrade, respectively). Windows 7 Home Premium will set you back $199, and an upgrade from either Vista or XP will cost you $119.

QUICK START GUIDE & USER’S MANUAL

2009-09-02T01:38:00.001-07:00

Table OF Content

Welcome 1

Check Components 3

Installation 4

Configuration 5

Troubleshooting 5

Welcome to the PC Remote control system which will give you a easy handling on presentations and multimedia activities. PC Remote Control lets you control all aspects of your computer from a remote control without using a keyboard or mouse you can use any remote control to configure the PCRC You Can do lot of actions as mentioned below.

Remote actions

Keyboard key press simulation.

You can specify if you want to use Alt, Ctrl or Shift.

Mouse

Movement and click control.

Execution

Of external applications.

Post Message

API function access which lets you send Windows type messages.

Volume

Control on volume.

Miscellaneous

Actions: Computer log off, reboot or shutdown.

On Screen Display

Of system parameters or free text

Installation

YOU should follow each step carefully as shown below in order to guarantee proper operation of PCRC set.

Connect the Rs 232 terminal to the computer using appropriate cable
Connect the USB cable to a USB port of the computer.
If it is good, the blue LED is indicated.
Try sending some signal to the receiver, if red led is blinking while sending signal then system sends signal to the computer.

PLACE THE PCRC SET

Place the device on the system unit or any other appropriate place where IR beam can easily pointed by IR sender.
Do not place the unit where external IR noises are high.
Avoid direct exposure to sunlight.

Configuration

You must configure device before using it. You may find lot of software which can configure IR receiver models. But we recommend using PC remote control by moises cambra. Other best option is use the winlirc. WinLIRC is the Windows equivalent of LIRC, the Linux Infrared Remote Control program. it is open source free software, but configuring it is little bit confuse for local usres.If you are using Linux, you have to use LIRC.

Configuring using Pc remote control is easy. Follow the instructions given by the help file and configure. You can configure four actions with the trial version of the software. You have to register the program to activate more commands.

Troubleshooting Tips

No Signal display when configuring

Check system is power on and serial cable is properly connected

Incoming signals are not identical for same button on remote

This can be happen if your serial port does not have enough serial port voltage. Especially, with the latest laptop computers that using low power RS232 interfaces ICs.