Nyquist Folding Receiver for the Interception of Frequency Agile Radar Signal

This work was carried out to improve the probability of interception of frequency sweep and lower the system complexity of non-sweep mode of the electronic intelligence system for frequency agile radar signal. A low complexity receiver structure and its associated demodulation algorithm with high probability of intercept are also presented. Moreover, the applicability of this structure for the wideband radar signal is demonstrated. First, the received signal is modulated by analog signal and treated as the local oscillator to move the local signal with different Nyquist zone into the baseband to extract the zone information. Then, the digital local oscillator synchronized with the analog modulation is used to reconstruct the demodulated sub-sampling signal. Finally, the zone and sub-sampling signal could be used to estimate signal parameters by the classical signal processing methods. Simulation results show that when the signal to noise ratio is more than -16 dB, the probability of correct decision for the Nyquist zone is better than 90%.