LFM Interference Mitigation Method Based on Robust Statistics

Global Navigation Satellite System (GNSS) signal interruptions can degrade the quality of service of GNSS-based applications. In order to solve the problem of the Linear Frequency Modulation (LFM) jamming on GNSS signal, this study applies a robust analysis method based on Joint Time-Frequency Analysis (JTFA) to improve the performance of GNSS receiver. The design of robust estimator in the Time-Frequency (TF) domain is realized through the Zero-Memory Non-Linearity (ZMNL) transformation, which is derived from considering the signal as conforming to two-dimensional Laplace distribution. In addition, Monte Carlo experiments are designed for verification of the effectiveness of the robust method. Although this method has a 0.325 dB Loss of Efficiency (LoE) in output Carrier to Noise Ratio (CNR) of the tracking loop compared with the traditional receiver under the jamming-free condition, its performance is better than that of the traditional JTFA method under the condition of LFM interference: under the condition of high jamming to noise ratio, the carrier to noise ratio of the tracking loop is increased by 7 dB. In high sweep rate and multiple LFM interference occasion, the jamming to noise signal ratio is increased by 20 dB under the condition of the receiver loop losing lock limit unchanged.