 Dr. Rupali Sherke from Volchin Institute of Technology working as an associate professor in electronic department. In this video lecture we are going to discuss with the pulse radar system. The learning outcomes of these sessions are after completion of this session students are able to draw and explain the pulse radar system, examine the different parts and working of each block which are used for inner pulse radar system. As we know that any radar system basically consists of the transmitter and the receiver part. A transmitter part transmit the electromagnetic waves which are transmitted towards the target and the reflected signal which are in the form of the receiver are restored by the receiver and which are displayed on the radar display. Here in this case in a radar communication both transmitter and the receiver both are situated at the same position pulse radar system. In a pulse radar system basically a transmitter part is consists of a trigger source, pulse modulator and output source which are connected with the duplexer to the antenna. And the receiver part consists of the RF amplifier, mixer, local oscillator, IF amplifier, detector, video amplifier and the radar display. This is a diagram which is showing the block diagram of the basic pulse radar system. Now let us see one by one the what are the blocks consist of and how the working of each blocks takes place. The first block is a trigger source. The function of the trigger source is to provide the impulse pulses sawtooth waveforms for the pulse modulator. The pulse modulator consists of a two inputs. One is the sign signal, sign wave where the sign waves are modulated by the pulses which are generated by the trigger sources. The pulse modulator gives the rectangular pulses which are modulated by the sign wave. Then the this pulse waveforms acts as a input to the output tube. The output tube is generally consists of an oscillator. If it is working for the high frequency then with the high power then it is using the magnetron and if it is a low frequency or a low power signals then it is using an impact or a gun diode. Basically this magnetron impact diode these all are the microwave devices which are used as an oscillator. Now if the output tube acts as an amplifier basically it is using the castron tube or a TWT which are also called as a microwave devices. The signals which are generated from the output tube are basically a are in the range of frequency range 3.9 gigahertz to 8 gigahertz which are working in a C band at a radar communication system. The output tube input is kept is fed to the duplexer. The duplexer which is gives the input to the antenna. The signals from the antennas are being transmitted into the free space. The basic function of the duplexer is that it exactly it is consists of the two tubes it is a gas discharging tube the tube and ATR tube. The basic function of the duplexer is to prevent the receiver while transmitting the high power as the transmitter power is high compared to the receiver power that is why the function of the duplexer is to prevent the receiver while transmitting the signal. The TRT tube is activated when it when it is receiving the signal and ATR tube is activated when it is transmitting the signal. Now, let us recall what is superhetrodynam principle the here it is also using the radar superhetrodynam receiver before that let us see what is a superhetrodynam receiver principle. The principle of the superhetrodynam is to convert the radio frequency signal into the intermediate frequency. The signals which are received by the antennas are the radio frequency signals and now first we have to convert them into the intermediate frequency which is known as a superhetrodynam principle. Now, the receiver part the receiver the received signals from the antenna are fed to the duplexer to the first block which is called as a RF amplifier. The function of the receiver is also to receive the proper signals which is interrupted due to the noise other interfacing signals and also due to the clustering. The received signals are in a form of eco signals or a reflected signals. The received signals are first which are in the band of the gigahertz frequency are received by the same antenna through the duplexer it has fed to the RF amplifier. The function of the RF amplifier consists of a low frequency which are in the range of 12 1 1 2 1 5 to 1400 megahertz. If it is using BJT for the for amplifying of the signals for the high frequency it is using the gallium arsenide fed as an amplifier. The output from the RF amplifier are first given to the mixer circuit. The one more input to the mixer circuit is from the local oscillator. The output of the mixer gives the radio frequency into the intermediate frequency which is fed to the intermediate amplifier. Here, IF amplifier which is a cascaded tuned amplifier the basic amplifier this amplifies the eliminate the noise and just provides the required bandwidth of the frequency. And the frequency range if it is a example for the air surveillance radar system it is a frequency range for the 30 to 60 megahertz with 1 megahertz bandwidth. The basic function of the receiver the gain of the receiver is totally dependent on the IF amplifier. So, it provides the receiver gain the output of the IF amplifier is fed to the detector circuit that for detecting the signals or to collecting back the original signals we are using the socket the barrier diode. The output of the diode is given to the video amplifier which amplifies the signals and then it is fed to the radar display. Now, this the interconnections of all these devices are made to the by the waveguides as the electron signals are in a form of the gigahertz frequency the normal coaxial cables cannot be supported that is why all these devices are connected through the waveguides. The radar display is used to represent the signals which are received by the superhetrodynam received the radar display may be a CRT 2 or ASCO. Now, this ASCO device works on the deflection modulation and this only determines the range of the target it only is provide the distance of the target from the location. This ASCO is represented in term like a X and Y axis which are received power volt versus the time. The second radar display can be a PPI radar system plane position indicator the plane position indicators are used to represent the works on the principle of intensity modulation and they are used for determining the range as well as the azimuth angle of the target. The how this is a diagram which shows the this is totally on the intensity modulation and it is represented in a form of polar plot the radius represent the time duration of that which is nothing but the range and the intensity gives the angle for that. The another display system is the computer is directly a data is fed to the and then they are displayed by the different to identify the range and the angle of the system. This in a pulse radar system the signals which are being transmitted in a pulses are received and the received pulses are being calculated and then they are fed to the radar display system. These are the few references through which I had collected the information for this presentation. Thank you.