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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 RADAR transmissiontransmission
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
λλ
FFd =d = doppler shift doppler shift
VVr 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.