Ppt Presentation on Radar@ Himank Charaya

RadarRadar&&

its Classificationits Classification

by: Himank by: Himank CharayaCharaya

OutlineOutline

1.1. Introduction to radar .Introduction to radar .2.2. Radar classification.Radar classification.3.3. Continous wave radar.Continous wave radar.4.4. Doppler effect.Doppler effect.5.5. Frequency-modulated CW Frequency-modulated CW

radar.radar.

RADARRADAR What is RADAR an acronym for? What is RADAR an acronym for?

Radio Detection and Ranging.Radio Detection and Ranging. Radio wave is generated, Radio wave is generated,

transmitted, reflected, and detected.transmitted, reflected, and detected. RADAR unimpaired by night, fog, RADAR unimpaired by night, fog,

clouds, smokeclouds, smoke RADAR is good for isolated targets RADAR is good for isolated targets

against a relatively featureless against a relatively featureless background.background.

The components of a radar system.The components of a radar system. 1. Transmitter 2. Antenna 3. Receiver 4. Display unit 5. Power supply 6. Duplexer( improved radar).

Two Basic Radar Two Basic Radar TypesTypes

Pulse Pulse

TransmissionTransmission

Continuous Continuous

WaveWave

Pulse TransmissionPulse Transmission

Continuous Wave Continuous Wave RadarRadar Employs continual Employs continual

RADAR transmissionRADAR transmission

Separate transmit Separate transmit and receive and receive antennasantennas

Relies on the Relies on the “DOPPLER SHIFT”“DOPPLER SHIFT”

Continuous Wave Continuous Wave RadarRadar

Continuous wave (CW) radars Continuous wave (CW) radars typically determine target typically determine target velocity, and can achieve velocity, and can achieve considerable ranges without considerable ranges without the high peak power. These the high peak power. These radars are typically simpler, radars are typically simpler, more compact and less costly.more compact and less costly.

Doppler EffectDoppler Effect that the Doppler effect is the that the Doppler effect is the

change in frequency that change in frequency that occurs when a source and a occurs when a source and a target are in relative motion.target are in relative motion.

The Doppler affect can be used The Doppler affect can be used in a CW radar in order to in a CW radar in order to determine velocity.determine velocity.

Doppler effect theoryDoppler effect theory FFd = d = 2V2Vrr

λλFFd =d = doppler shift doppler shiftVVr r = relative velocity of target = relative velocity of target

with respect to radar.with respect to radar.

Doppler Frequency Doppler Frequency ShiftsShifts

Motion Away: Echo Frequency Decreases

Motion Towards:Echo Frequency Increases

Continuous Wave Continuous Wave Radar ComponentsRadar Components

Discriminator AMP Mixer

CW RFOscillator

Indicator

OUTOUT

ININ

Transmitter Antenna

Antenna

FM-CW radarFM-CW radar An unmodulated CW radar is An unmodulated CW radar is

incapable of detecting range, as incapable of detecting range, as there is no reference point in the there is no reference point in the transmitted or returned signal transmitted or returned signal for measuring elapsed time.for measuring elapsed time.

By frequency modulating the CW By frequency modulating the CW signal, differences between the signal, differences between the transmitted and received frequencies transmitted and received frequencies can be used to estimate range.can be used to estimate range.

Pulse Vs. Continuous Pulse Vs. Continuous WaveWave

Pulse EchoPulse Echo Single AntennaSingle Antenna Gives Range, Gives Range,

usually Alt. as usually Alt. as wellwell

Susceptible To Susceptible To JammingJamming

Physical Range Physical Range Determined By Determined By PW and PRF.PW and PRF.

Continuous WaveContinuous Wave Requires 2 Requires 2

AntennaeAntennae Range or Alt. InfoRange or Alt. Info High SNRHigh SNR More Difficult to Jam More Difficult to Jam

But Easily DeceivedBut Easily Deceived Amp can be tuned Amp can be tuned

to look for expected to look for expected frequenciesfrequencies

Specific Types of Specific Types of RadarRadar

Frequency Modulated CW Radar Frequency Modulated CW Radar Use for radar altimeters and missile guidance.

Pulse DopplerPulse Doppler Carrier wave frequency within pulse is compared

with a reference signal to detect moving targets. Moving Target Indicator (MTI) SystemMoving Target Indicator (MTI) System

Signals compared with previous return to enhance moving targets. (search radars)

Frequency Agile SystemsFrequency Agile Systems Difficult to jam.

Thank you.Thank you.