A Receiver for Doppler Estimation Capable Waveforms Utilizing Chirp Signature Diversity

Abstract

This paper discusses a receiver for a new class of Doppler estimation capable radar waveforms formed by appending a CDMA signature to a Doppler estimation capable radar waveform in a separate frequency band. The CDMA signature is created from a sequence of modulated linear chirp functions. Reception begins by separating the radar and signature bands via a bandpass filter, digitizing, and feeding the resulting signals into separate data buffers. The receiver is time sychronized and the Doppler shift is estimated by matched filtering the radar waveform. The CDMA signature is decoded by convolving the chips with a Doppler adjusted matched filter, thresholding, sampling at the peaks, and finding the closest signature in a codebook. This paper illustrates these waveforms, their receiver, and their performance against Swerling III and IV targets, noise, and a Doppler shift.