Question

A defense radar system is operating at 20GHz and the target speed range is found to be 0.5 to 3 times the sound speed (334.4 m/s) while the radar speed resolution is selected 10 m/s. For this radar system:

i. What is the required spectral frequency range for a filter bank that is needed to detect Doppler shift? And

ii. How many narrowband filters are required for this filter bank?

Answer 1

Spectral frequency range can be determined using Doppler shift formula

c is the speed of sound and v is speed of receiver target

So for v= 0.5c

And for v= 3c

So the required frequency range to observe doppler shift is

30GHz to 80 GHz

2) and because the speed resolution is 10m/s so minimum frequency shift to be observed is

So frequency shift is ,

And spectral rage is

So narrow bands required are

I have done this calculation for target moving toward radar to show doppler shift you can do same with v changes to -v for target moving away from radar as question not mentioned clearly in which direction it is moving.