Revisiting Velocity Ambiguity

A technique originally employed in a US fighter aircraft attack radar has been adapted to eliminate velocity ambiguity (aka aliasing, or folding) in coherent pulsed Doppler weather radars. The transmitted pulse, or carrier, is modulated with a longer wavelength signal. Doppler computations are then performed on the detected modulation rather than on the carrier. The unambiguous velocity is thereby decoupled from pulse repetition frequency and carrier wavelength. The possibility of extending this technique to pseudo-coherent systems is also discussed.