Parameter Estimation of LFM Signal Intercepted by Synchronous Nyquist Folding Receiver Based on Instantaneous Autocorrelation

Abstract

The Nyquist Folding Receiver (NYFR) samples signals at sub-Nyquist rates to fold the ultra-wideband (UWB) signal into an analog interpolation filter. The RF local oscillator signal (LOS) used in NYFR introduces modulation related to the Nyquist-zone (NZ) on the received signal so that signal information can be separated and recovered from the sparse wideband RF environment. As a consequence, NYFR can enable broadband surveillance via one low-speed analog-to-digital converter (ADC) in theory. The synchronous NYFR breaks through the disadvantage of NYFR being susceptible to noise and unable to extract initial phase. An NZ and chirp rate estimation algorithm for linear frequency modulation (LFM) signals considering two-time delay instantaneous autocorrelation is proposed in this paper. The simulation results show that when the signal to noise ratio (SNR) is greater than -8dB, the parameter estimation accuracy of the algorithm reaches near 100%.