Anti-Sweep-Jamming Method Based on the Averaging of Range Side Lobes for Hybrid Modulation Proximity Detectors

Hybrid modulation continuous waveform (HMCW) proximity detectors emit binary phase-coded chirp (BPCC) waveforms. Therefore, they possess the advantages of binary phase-coded modulation and chirp modulation simultaneously. To enhance the anti-sweep-jamming performance of HMCW detectors, this paper analyses the response of an HMCW detector under sweep jamming and proposes an anti-jamming method based on the novel average range side lobe (ARS) approach. Similar to the instant correlation with harmonic demodulation (ICHD) method, the ARS method also combines time-domain instantaneous correlation with frequency-domain harmonic demodulation to obtain the range information of the target. The difference is that the ARS method uses a fast Fourier transform (FFT) instead of a band pass filter (BPF) to extract the harmonic envelope and averages multiple harmonic coefficients obtained via the FFT. Because the correlation side lobes of chaotic codes follow a Gaussian distribution, the output of an HMCW detector under sweep jamming is suppressed after ARS processing. The proposed method is proven to be feasible and effective through numerical simulations. The results show that the ARS method offers improved anti-sweep-jamming performance.