Working of a Pulse RADAR and its applications
In this article, a brief introduction is given about the basic working concept of a RADAR system along with block diagram. RADAR is a system similar to SONAR. But difference is, SONAR is used to detect under water objects. Now a days RADAR is finding a vast range of application in various fields. Some interesting applications are discussed in this section.
Acronym RADAR stands for RAdio Detection And Ranging. Radar is an electromagnetic system used to detect the objects which are not visible to normal eye sight. It can be used to detect aircrafts, ships, space vehicles etc... Such objects which are detected by Radar are called 'targets'. There are many types of radars based on their area application. It can be used in air force, weather forecasting, to measure speed and shape of the moving target etc.
Now let us see a brief description of a pulse Radar. It is mainly used to detect the presence of any target in the range of Radar. The block diagram of the same is shown below:
Description:
A low power signal is produced by the waveform generator which is given as an input to the power amplifier.
The power amplifier (Such as Klystron, TWT) produces a high power signal, may be in terms of megawatts. Pulse modulator shown in the block is used as a switch, which will turn on and off the power amplifier.
For both transmission and receiving purpose we will use a single antenna. The operation is achieved by using a duplexer. Duplexer connects the antenna to the transmission section during the process of transmission of the signal. Then it isolates transmission section and connects to the receiver section during the reception of the signal. Antenna used here is usually a parabolic reflector type.
The receiver section is of super heterodyne type. As seen from the block diagram, the first block is a low-noise RF amplifier. Combination of mixer and local oscillator will convert RF signal to an intermediate frequency (IF).
The combination of IF amplifier and Matched filter stage will increase the output signal to noise ratio (S/N).
The output of IF amplifier is connected to a detector. Demodulation of the signal is done here. And then it is fed to video amplifier. The output of video amplifier is given to the threshold detector where it is decided whether the received signal is from a target or just because of the presence of noise. The output pulse is displayed on CRT (Cathode Ray Tube). Commonly used CRT display is PPI (Plan-Position Indicator). Even A-scope display can be used for the same. Applications of RADAR:
• Military purpose
• Remote sensing
• Air traffic control
• Weather interpretation
• Ground probing
• Aircraft safety & navigation
• Tracking of icebergs on the sea
• Planetary research
• Highway safety and enforcement of speed limit system
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