Removal of aliasing in pulse-to-pulse Doppler radar measurements


  • John D. Sahr,

  • Donald T. Farley,

  • Wesley E. Swartz


Frequency aliasing is a problem often encountered in pulsed radar studies of some deep targets, such as the radar aurora. It is possible to resolve the aliasing ambiguities by transmitting closely spaced pulse pairs, rather than single pulses. Instead of the usual power spectrum, we compute a cross spectrum of the received signals. The amplitude of this cross spectrum is just the normal, possibly aliased, power spectrum, and the phase determines the aliasing, if any, at each frequency bin. The technique works as long as the spectrum is not seriously wrapped around upon itself, that is, as long as each frequency bin is dominated by signals with a single Doppler shift, no matter what that Doppler shift may be. The price paid for this extra information is the addition of radar clutter, uncorrelated signals from unwanted ranges, but this price may be acceptable.