Doppler radar is a Radar system that exploits the Doppler Effect to measure the radial velocity of a target in addition to its range. When a target moves toward or away from the radar, the reflected signal is frequency-shifted relative to the transmitted pulse:
where is the Doppler frequency shift, is the radial velocity of the target, and is the wavelength of the transmitted signal. A target moving toward the radar produces a positive shift; moving away produces a negative shift.
Pulse-Doppler Radar
A common implementation that transmits a train of pulses and computes the phase shift between successive returns from the same target. An FFT across the pulse train converts phase progression into a Doppler frequency bin, allowing simultaneous range and velocity measurement.
Applications
- Weather radar: maps precipitation velocity to detect rotation (tornadoes)
- Air traffic control: separates moving targets from stationary clutter
- Speed enforcement: measures vehicle radial velocity directly