PRESENTATION ONPRESENTATION ONCW DOPPLER RADARCW DOPPLER RADAR

Prepared by,Prepared by,Anurag poojariAnurag poojariAbhijit PujariAbhijit PujariHarshad RaneHarshad RaneChirag RangrassChirag RangrassMandar RaneMandar Rane

Presentation OutlinePresentation Outline INTRODUCTIONINTRODUCTION PRINCIPLEPRINCIPLE WORKINGWORKING ADVANTAGESADVANTAGES DISADVANTAGESDISADVANTAGES APPLICATIONAPPLICATION CONCLUSIONCONCLUSION

cw doppler radar uses the doppler effect to detect the cw doppler radar uses the doppler effect to detect the frequency change caused by a moving target,and displays this frequency change caused by a moving target,and displays this as a relative velocity.as a relative velocity.

Continuous-wave radar system is a radar system where a known stable frequency continuous wave radio energy is transmitted and then received from any reflecting objects. The return frequencies are shifted away from the transmitted frequency based on the Doppler effect if they are moving.

The Doppler effect (or Doppler shift), named after Austrian physicist Christian Doppler who proposed it in 1842, is the change in frequency and of a wave for an observer moving relative to the source of the waves. It is commonly heard when a vehicle sounding a siren approaches, passes and recedes from an observer. The received frequency is increased (compared to the emitted frequency) during the approach, it is identical at the instant of passing by, and it is decreased during the recession.

Doppler Shift: A frequency shift that occurs in electromagnetic waves due to the motion of scatterers toward or away from the

observer.

PRINCIPLEPRINCIPLE

Sign conventionsThe Doppler frequency is negative (lower frequency, red shift) for objects receding from the radar

Red: Receding from radar

Blue: Toward radar

The Doppler frequency is positive (higher frequency, blue shift) for objects approaching the radar

TRANSMITTERTRANSMITTER MIXER MIXER

ft

ft

fi

ft +fI

ft ±fd

ft ±fd

fd

ADVANTAGESADVANTAGES

Its is limited in the maximum power its transmits.

It is incapable of indicating the range of the target, it can only measure its velocity.

Can not detect moving target easily.

Can not measure range

APPLICATIONAPPLICATION

Cw Doppler radar is a simple radar which uses the Doppler effect to detect the frequency change caused by a moving target ,& displays this as a relative velocity.

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