Abstract

A synchronous Nyquist folding receiver (SNYFR) could intercept wideband signals in multi-Nyquist zones with two analog-to-digital converters. The instantaneous Nyquist zone (INZ) of the SNYFR may not exist or is not unique, and the dual local harmonics was presented to improve the stability of the SNYFR. It was found that the existence and unique conditions of the INZ determined that the frequency of the local oscillator signal (LOS) in one zone was constant. A symmetrical low-pass filter and dual harmonics LOSs were adopted to facilitate the detection of the INZ. Simulations showed that the proposed structure is valid for the interception of wideband radar signal.

Key words: Electronic countermeasures, parameter estimation, linear frequency modulation, synchronous Nyquist folding receiver.