Synchronisation of bistatic radar using chaotic AM and chaos-based FM waveforms

摘要

The authors developed a technique to synchronise a bistatic radar that uses a chaotic system to generate and process either wideband amplitude modulated (AM) or frequency modulated (FM) waveforms thereby extracting high-resolution information from the targets. For chaotic AM bistatic radar, a generalised projective synchronisation approach that includes a driving oscillator at the transmitter and a response oscillator at the receiver is considered. The receiver accepts a scaled version of the transmitted waveform where the scaling factor α accounts for space propagation losses that may not be known a priori. However, AM synchronisation is highly susceptible to noise. Alternatively, FM bistatic radar is implemented with a chaos-based FM waveform. Demodulation of this waveform using a phase lock loop is required to recover the instantaneous frequency which represents a chaotic state variable. The recovered and transmitter instantaneous frequencies are synchronised by using either generalised projective synchronisation or complete replacement synchronisation. The synchronised output is then used to reconstruct the FM waveform. They show that the short-time cross-correlation of the transmitted and reconstructed waveforms is high and its self-noise is negligible. Through entropy analysis of the cross-correlogram, they found that the bistatic FM radar performs better than the bistatic AM radar.