Doppler Shift Calculator

Calculate frequency shift due to relative motion for radar targets and satellite links.

What is the Doppler Effect?

An ambulance siren sounds higher-pitched as it approaches and lower-pitched as it drives away — that's the Doppler effect. Radio waves behave exactly the same way: a signal from a moving source arrives at a slightly different frequency than it was transmitted at.

Why it matters: Speed cameras and weather radar both use Doppler to measure how fast things move. Satellite ground stations must compensate for Doppler shift so communications stay locked even as a satellite streaks overhead at 17,000 mph.

Radar Doppler
Monostatic radar with moving target. Doppler is doubled on round trip.
GHz

The frequency the radar transmits at. Higher frequencies give more Doppler shift per km/h of speed

m/s

How fast the target is moving toward or away from the radar. Positive = approaching. 100 m/s ≈ 360 km/h

Hz

How often the radar sends pulses — limits the maximum speed it can measure without ambiguity

Radar Doppler Results
Doppler Shift6.338kHz6.3377 kHz

Doppler Shift

6.3377 kHz

Velocity (cross-check)

100.00 m/s

Max Unambiguous Velocity (at PRF)

±7.89 m/s (28.4 km/h)