the same location as the transmitter. Although the signal returned is usually very weak, the signal can be amplified. This enables radar to detect objects at ranges where other emissions, such as sound or visible light, would be too weak to detect. Radar is used in many contexts, including meteorological detection of precipitation, measuring ocean surface waves, air [4] traffic control, police detection of speeding traffic, and by the military. Fig.3.1: DETTECTION AN AIRCRAFT USING RADAR 3.1 PRINCIPLE A radar dish or antenna sends out pulses of radio waves or microwaves. These waves bounce off any object in their path, and return to the dish, which detects them. The time it takes for the reflected waves to return to the dish enables a computer to calculate how far away the object is, its radial [4] velocity and other characteristics. 3.2 Distance Measurement One way to measure the distance to an object is to transmit a short pulse of radio signal (electromagnetic radiation), and measure the time it takes for the reflection to return .The distance target is one half the product of the time taken by the radiated signal to travel to the target and back to the receiver and the speed of the signal radiated.[4] 3.3 Frequency modulation Another form of distance measuring radar is based on frequency modulation. Frequency comparison between two signals is considerably more accurate, even with older electronics, than timing the signal. By changing the frequency of the returned signal and comparing that with the original, the difference can be easily measured.[4] 3.4 Speed measurement Speed is the change in distance to an object with respect to time. Speed measurement is done by using the technique of droppler effect. The radar beam is fired at the moving target. As it recedes from the radar source, each
the same location as the transmitter. Although the signal returned is usually very weak, the signal can be amplified. This enables radar to detect objects at ranges where other emissions, such as sound or visible light, would be too weak to detect. Radar is used in many contexts, including meteorological detection of precipitation, measuring ocean surface waves, air traffic control, police detection of speeding traffic, and by the military. [4] Fig.3.1: DETTECTION AN AIRCRAFT USING RADAR 3.1 PRINCIPLE A radar dish or antenna sends out pulses of radio waves or microwaves. These waves bounce off any object in their path, and return to the dish, which detects them. The time it takes for the reflected waves to return to the dish enables a computer to calculate how far away the object is, its radial velocity and other characteristics. [4] 3.2 Distance Measurement One way to measure the distance to an object is to transmit a short pulse of radio signal (electromagnetic radiation), and measure the time it takes for the reflection to return .The distance target is one half the product of the time taken by the radiated signal to travel to the target and back to the receiver and the speed of the signal radiated.[4] 3.3 Frequency modulation Another form of distance measuring radar is based on frequency modulation. Frequency comparison between two signals is considerably more accurate, even with older electronics, than timing the signal. By changing the frequency of the returned signal and comparing that with the original, the difference can be easily measured.[4] 3.4 Speed measurement Speed is the change in distance to an object with respect to time. Speed measurement is done by using the technique of droppler effect. The radar beam is fired at the moving target. As it recedes from the radar source, each