The mechanics of Aircraft Flutter - Doppler Shift

Far

F

Fas

?

?

F = Frequency of transmission

Far = frequency of received signal at aircraft

Fas = frequency of received signal, at viewer’s

TV receiver, sent from aircraft.

F

wf

wfas

(wfas - wf )

Doppler shift

Direct signal

Ghost signal (doppler shifted)

RF envelope

Detected video signal :

Direct

Ghost

time

tg

Amplitude variation

at doppler frequency

Far = F - F * Cos ? * Va / c

Fas = Far + Far * Cos ? * Va / c

As (F * Cos ? * Va / c) <<< F :

Fas = F - F * Cos ? * Va / c + F * Cos ? * Va / c

ie : Fas = F + sum of doppler shifts

Va

Va = Speed of aircraft

c = Speed of light (constant)

Incident

Reflected

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