Optimum Unbiased Estimation Algorithms for Solving the Range Sidelobe Problem in Radars using Expanded Waveforms

The conventional method of signal processing in the receivers of radar systems using expanded waveforms is based on filtering the received signal by a filter matched to the expanded waveform. This kind of signal processing is not optimum because of the range sidelobes. In this paper, an optimum unbiased estimation algorithm is proposed which eliminates the range sidelobes totally. The prize to be paid for this elimination is a signal-to-noise ratio (SNR) degradation in comparison to matched filtering. It will be shown that for a large class of expanded waveforms this SNR degradation is in the order of 1dB or less. A suboptimum alternative of the optimum algorithm will also be presented. This alternative can be implemented in the form of a mismatched filter and is less expensive than the implementation of the optimum algorithm.