PRESENTED BY:PRESENTED BY:Mustahid ALIMustahid ALI

WHAT IS RADAR?WHAT IS RADAR? RADAR (Radio Detection And RADAR (Radio Detection And

Ranging) is a way to detect and study Ranging) is a way to detect and study far off targets by transmitting a radio far off targets by transmitting a radio pulse in the direction of the target and pulse in the direction of the target and observing the reflection of the wave.observing the reflection of the wave.

Radar observables:• Target range• Target angles (azimuth & elevation)• Target size (radar cross section)• Target speed (Doppler)

Antenna

TransmittedPulse

TargetCross

Section

Propagation

ReflectedPulse

(“echo”)

RADAR SIGNAL PROCESSINGRADAR SIGNAL PROCESSING

a) Distance Measurementa) Distance Measurement

1. transit time1. transit time

2. frequency modulation2. frequency modulation

b) Speed measurementb) Speed measurement

c) Reduction of interference effectsc) Reduction of interference effects

d) Plot and track extractiond) Plot and track extraction

DISTANCE MEASUREMENTTransit time: 1.The round trip time for the radar pulse to

get to the target and return is measured. 2.The distance is proportional to this time. 3. The distance is one half the product of the

round trip time and the speed of the signal.

Radar Range Measurement

Transmitted

Pulse

Reflected

Pulse

Range

Target

• Target range = c2

where c = speed of light = round trip time

FREQUENCY MODULATIONAnother 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 measuring the frequency of the returned signal and comparing that with the original, the difference can be easily measured.

2. Speed measurementSpeed is the change in distance to an

object with respect to time. Thus the existing system for measuring

distance, combined with a memory capacity to see where the target last was, is enough to measure speed.

There is another effect that can be used to make almost instant speed measurements known as the Doppler effect.

REDUCTION OF INTERFERENCE EFFECTS:Signal processing is employed in radar

systems to reduce the radar interference effects.

Signal processing technique include MTI, pulse Doppler, constant false alarm rate and digital terrain model(DTM) are also used in clutter environments.

Doppler effect:The Doppler effect is a frequency shift that

results from relative motion between a frequency source and a listener.

The Doppler shift is directly proportional to speed between source and listener, frequency of the source, and the speed the wave travels.

RADAR SIGNAL PROCESSOR

The signal processor is that part of the system which separates targets from clutter on the basis of Doppler content and amplitude characteristics.

In modern radar sets the conversion of radar signals to digital form is typically accomplished after IF amplification and phase sensitive detection.

Military applicationNavigational radarsRadar altimetersAir traffic controlLaw enforcement and highway safety