Passive Angle-Doppler Profile Estimation for Narrowband Digitally Modulated Wireless Signals

In this paper, we improve estimation of the Doppler shift present in signals that originate from multiple wireless digital communication transmitters. We deploy a uniform linear array (ULA) that overhears the frequency band of interest, hence an unauthorized wireless receiver (URx), and propose an algorithm for extracting the symbol duration from the unknown modulated data. The baseband wireless modulated signal is stripped from its data-induced phase shifts, allowing us to calculate high quality estimates of the periodogram, the spectrogram, and the angle-Doppler profile. Performance results show that high quality results without artifacts from digital modulation can be obtained.