Suppression of NAM Interference Based on VMD and Threshold Detection for FM Detector

The increasingly complex environment of the modern battlefield seriously threatens the detection performance of the detector. In order to improve the anti noise amplitude modulation(NAM) interference ability of the frequency modulation detection system, this paper analyses the difference between the interference signal and the echo signal in time domain and frequency domain after mixing with the local oscillator, points out that the interference signal is a frequency modulation signal and the echo signal is a single frequency signal, and proposes an anti-interference method based on variational mode decomposition(VMD) and threshold detection, which decomposes the signal into several intrinsic mode functions (IMF) of different frequency bands and screens out the echo-containing signal mode. The simulation results show that the proposed method can effectively suppress the noise amplitude modulation interference and achieve accurate target ranging.