Electronics

Introduction to MATLAB graphics

2013-03-03T18:01:00.000+05:30

MATLAB has a large number of functions associated with graphical output. If you'd like to explore the possibilities use help plot or help plot 3 for 3-dimensional plots, or run the MATLAB demo (by typing demo) and look at the information on visualization and graphics. We start with basic plotting routines and look at some fancy graphics to get a taste of MATLAB’s abilities.

Suppose that the maximum and minimum temperature (in degrees Celsius) recorded from 12 to 18 January are 23, 27, 21, 28, 24, 25, 26, and 11, 10, 15, 15, 14, 15, 12 respectively.

1) Set up the vector 'date' to have elements from 12 to 18, and the vectors 'maxtemp' and 'mintemp' to contain the temperature data given above. It does not matter whether the vectors are row or column vectors.

All the vectors are of the same length so it is possible to plot one against the other.

2) Create a plot of the maximum temperatures by typing plot(date, maxtemp) The x-axis variable is listed first. This graph will be created in a window called Figure No. 1. If this window is not visible select Figure No. 1 under Window on the menu. Your graph should look like the one below.

3) Now type plot(date,mintemp) . The previous plot disappears and the new plot is displayed.

We can also plot both graphs in one figure:

4) Type plot(date,maxtemp); followed by hold on; Then type plot(date, mintemp); followed by hold off; hold on tells MATLAB to keep the old plot and add the new graph to it. hold off turns the hold-feature off again. We could also have used plot(date, maxtemp, date, mintemp); which tells MATLAB to plot maxtemp against date and then mintemp against date in the same graph. The colors of the graphs are then different.

5) Select Insert from the figure window and then Title. A text box will appear in the figure window. Type '12-18 January'. Now add the label 'date' to the x-axis and 'temp (Celsius)' to the y-axis using the appropriate selections under Insert.

6) Select Edit and then Axes properties. Un-select Auto for X (click in the Auto box to remove the tick). Then change the limits of 12 and 18 for the x-axis to 11.5 and 18.5 respectively. Now change the limits for the y-axis to 9 and 30. If the Immediately apply box at the bottom of the Axes Properties window is not ticked you must click OK to see the changes.

7) Click on the graph corresponding to the maximum temperature. Then select Current Object Properties under Edit in the figure window. Select No line (none) under Line Style. Under Marker Properties, select a marker of your choice, eg. Six-pointed star. Choose a nice color.

8) Repeat for the graph corresponding to the minimum temperature with a different color and marker.

9) To add a legend, select Insert then Legend. You can change the description of the graphs in the legend by double clicking on the text in the figure window. Change the descriptions to 'maxima' for the maximum temperature graph and 'minima' for the minimum temperature graph.

10) Select Insert, then Text (or click on the A button on the menu). Move your mouse to the plot window. Position the cursor near the highest point in the graph and click. Type 'highest' in the field.

The final graph is shown below:

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Night Vision Technology

2013-02-24T16:41:00.001+05:30

Night vision technology, literally allows one to see in the dark. It is originally developed for military use .Humans have poor night vision compared to many other animals.With the proper night-vision equipment, we can see a person standing over 200 yards (183 m) away on a moonless, cloudy night.

Types of Night Vision device:

1) Image intensification (light amplification) and

2) Thermal imaging(infrared).

IMAGE ENHANCEMENT COMPONENTS

Front lens
Photo cathode
Micro Channel Plate
High Voltage Power Supply
Phosphor Screen
Eyepiece
Image Intensifier

v IMAGE INTENSIFICATION

It is also called light amplification

It is less expensive than thermal

Light amplification technology takes the small amount of light, such as moonlight or starlight, that is in the surrounding area, and converts the light energy (scientists call it photons), into electrical energy (electrons).

These electrons pass through a thin disk that's about the size of a quarter and contains over 10 million channels.

As the electrons travel through and strike the walls of the channels, thousands more electrons are released.

These multiplied electrons then bounce off of a phosphor screen which converts the electrons back into photons and lets you see an impressive nighttime view even when it's really dark.

v THERMAL IMAGING

SPECIFICATIONS

Scan 30 times per sec.

Sense temperature ranging from -20 to 2,000 degree Celsius.

It shows a very minute difference of as small as 0.1 degree Celsius from more than 1,000 ft away.

v TYPES OF THERMAL IMAGING DEVICES

v GENERATION OF NVT:

Generation 0
Generation 1
Generation 2
Generation 3
Generation 4
Generation 0

The earliest (1950's) night vision products were based on image conversion, rather than intensification.

Generation 1

Vacuum Tube Technology
Full Moon Operation
Amplification: 1,000
Operating Life: 2,000 Hours

Generation 2

First Micro channel Plate Application
One-Quarter Moon Operation
Amplification: 20,000
Operating Life: 2,500 Hours

Generation 3

Improved Micro channel Plate & Photo cathode
Starlight Operation
Amplification: 40,000
Operating Life: 10,000 Hour

Generation 4

Generation 4 has less noise than generation 3, however it has shorter life.

Improvements

MCP & Photo cathode
Starlight Operation
Amplification: 40,000
Operating Life: 10,000 Hour

APPLICATIONS

- Military
Law enforcement
Hunting
Wildlife observation
Surveillance
Security
Navigation
Hidden-object detection Entertainment

v NIGHT VISION DEVICES

SCOPES : They are monocular normally handheld or mounted on a weapon.
GOGGLES: They are binocular and worn on the head.
CAMERAS: Used for transmission or recording of images mostly if the location is fixed.

v FUTURE ASPECTS

1.The Army is pushing NVT into the digital aspects. Future NV goggles are being designed not just to see better at night but also to allow soldiers to share images of what they see with other soldiers who may be miles away.

2. Technologists are working to meet the challenges of the Army, which includes their requirements for power of capture, size and weight of equipment.

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Introduction to Arduino

2013-02-18T17:50:00.000+05:30

What is Arduino?

Arduino is a tool for making computers that can sense and control more of the physical world than your desktop computer.

Arduino is an open source physical computing platform based on a simple input/output (I/O) board and a development environment that implements the Processing language. Arduino can be used to develop standalone interactive objects or can be connected to software on your computer (such as Flash, Processing, or Max/MSP).

The boards can be assembled by hand or purchased preassembled; the open-source IDE can be downloaded for free on www.arduino.cc

How differs from others?

Multiplatform Environment so it can run on Windows, Linux, Macintosh.
Easy to use Development environment
Programmable via USB port, not Serial port
Easy-to-use for beginners, yet flexible enough for advanced users to take advantage
Open source and extensible software- The Arduino software is published as open source tools, available for extension by experienced programmers.
Open source and extensible hardware - The Arduino is based on Atmel's ATMEGA8 and ATMEGA168 microcontrollers.

Arduino Board

Arduino Development Environment

The Arduino development environment contains a text editor for writing code, a message area, a text console, a toolbar with buttons for common functions, and a series of menus. It connects to the Arduino hardware to upload programs and communicate with them.

Software written using Arduino are called sketches. These sketches are written in the text editor. Sketches are saved with the file extension .ino.

reference: arduino.cc , Getting Started with Arduino by Massimo Banzi

You can download eBook Getting Started with Arduino by Massimo Banzi from Here

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RFID Technology

2013-02-14T16:42:00.000+05:30

How Does RFID ( Radio Frequency Identification) Technology Work?

RFID is an intelligent application of radio communication technology. Every RFID tag embedded in a product contains an integrated circuit chip,with memory, which can be used to store information about a product, along with a transponder mechanism, which can transmit this information over a radio carrier wave after encoding and modulating it.

An RFID tag can either be active or passive. When the tag is powered by a battery to transmit data, it's known as an active tag. Passive tags don't have on board power to transmit data. They borrow energy from the scanner antenna in the RFID reader to transmit data. An RFID reader consists of a scanning antenna which can receive signals from the tags, decode them and process them for storing it in a database. Here is how a typical RFID tag reading occurs.

Step 1: RFID Antenna Sends Scanning Signal
An RFID tagged product may either be passed through a reader or scanner or brought into the vicinity of one. Line of sight identification is not necessary in case of RFID technology and the tags are embedded inside a product. The tag reading process begins with the RFID antenna sending a scanning signal which activates the transponder in a tag to respond. The scanning frequency is chosen to match with the transmitting frequency of the transponder.

Step 2: RFID Tag Transmits Signal
As soon as the active or passive RFID transponder receives the scanning signal, it sends out its own encoded and modulated signal over a radio carrier wave. Active RFID tags can transmit signals over long distances.

Step 3: Tag Signal is Received, Decoded and Stored
This transmitted signal is received by the reader through its tuned antenna. Subsequently, the signal is demodulated and decoded to register product information in a database. These RFID scanners are attached to computers where this information is stored.

Bulk identification of products and short scanning time are two of the prime advantages of using RFID tags, instead of bar code labels. RFID tags find varied applications. They have been used to track dwindling populations of animals in the wild. Employee ID cards have built in RFID tags, encased in plastic layers that are used in most corporate and industrial settings nowadays. The US army is one of the biggest patrons of this technology, using it to tag all containers transported worldwide, followed by Walmart which uses the technology in all its retail outlets. RFID chip implants in humans have been used for providing medical history and identification purposes.

image source en.Wikipedia.com

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Software introduction

2012-08-26T16:03:00.002+05:30

Matlab is the software developed by the MathWorks, Inc., Natick, USA. In 1984, the first
version appeared. Software was primarily used only for the mathematical computation
enabling the computation of complicated matrix equations and their systems. All major
functions can directly use the matrix as the input. From that year, the software is still under
development enlarging the area of the users every year. Matlab became the standard in the
area of simulation and modelling and it is used by the researchers and students at
universities mainly in the areas of Control Engineering, Power Plant Systems, Aerospace,
Bioinformatics, Economics and Statistics. In comparison to other software such as
Mathematica or Maple, Matlab has several advantages. Let us mention some. Its open
architecture enables sharing all source code among the user community and several
different areas are solved and the solution appears usually as a new toolbox. Simulink is the
important Matlab enlargement which simplifies the computation very much. You just drag
and drop the blocks to the new window from the block libraries and connect them and run
the model. Matlab is used not only at universities but also in practice, for instance by NASA
or General Motors. Most Matlab users are from the major world countries, such as USA,
Japan, China, and India.

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MATLAB introduction

2012-08-26T15:01:00.001+05:30

About MATLAB

The Golden Ratio:-What is the world's most interesting number? Perhaps you like ¼, or e, or 17.
Some people might vote for Á, the golden ratio, computed here by our ¯rst Matlab
statement.
phi = (1 + sqrt(5))/2
This produces
phi =
1.6180
Let's see more digits.
format long
phi
phi =
1.61803398874989

If you have forgotten the quadratic formula, you can ask Matlab to ¯nd
the roots of the polynomial. Matlab represents a polynomial by the vector of its
coe±cients, in descending order. So the vector
p = [1 -1 -1]
represents the polynomial
p(x) = x2 ¡ x ¡ 1:
The roots are computed by the roots function.
r = roots(p)
produces
r =
-0.61803398874989
1.61803398874989
These two numbers are the only numbers whose reciprocal can be computed by
subtracting one.

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