Estimation of Doppler Centroid of Fading Radar Targets

The echo from a rapidly fading radar target may have a Doppler spectrum which is wider than the Doppler resolution cell. In tracking the target in Doppler, estimates of the centroid of the target Doppler spectrum may be used. Here, the target echo is modeled as a complex Gaussian random process modulated by the radar pulse shape. The variance for a particular estimator of the Doppler centroid is evaluated in terms of the signal power spectral density. In the noise-free case, this variance is shown to be independent of the radar Doppler resolution provided the resolution is coarse with respect to the target Doppler spectrum width, and directly proportional to the Doppler resolution when the resolution is relatively fine. The analysis is also applicable to dual problems of delay-distributed or angle-distributed targets.