Fractional Range Migration Compensation and Doppler Ambiguity Resolution for Pulse Doppler Radars Using Variable Chirp Rate Signals and Pulse Compression With Partial Reference Signals

We present a method that simultaneously addresses range migration compensation and Doppler ambiguity resolution for fast-moving targets in pulse Doppler radars. Although pulse Doppler radars are used for high-sensitivity and high-resolution target detection, problems arise when target velocities exceed the Nyquist limit. These problems include a decrease in detection probability due to range migration loss and Doppler ambiguity caused by the folding of the Doppler velocity. Several methods have been proposed to tackle these problems. However, achieving simultaneous resolution remains challenging due to high computational demands and interference between methods in some cases. Our approach integrates a range migration compensation method that uses variable chirp rate signals with a velocity estimation method that employs pulse compression using partial reference signals (i.e., portions of the reference signal) to detect the intra-pulse Doppler-shift frequency difference. However, these methods do not yield satisfactory results when simply integrated; therefore, modifications are applied to each method prior to their combined use. Numerical simulations demonstrate that our method effectively mitigates the decrease in detection probability while estimating target velocities beyond the Nyquist limit.