Novel Anti-Deception Jamming Method by Measuring Phase Noise of Oscillators in LFMCW Tracking Radar Sensor Networks

Abstract

In this paper, the effects of phase noise difference in receiving signals are introduced to discriminate targets. Oscillators and signal sources have their own phase noise levels and specific patterns. This property can be used for discriminating a real target from the airborne digital radio frequency memory (DRFM) in continuous wave tracking radar sensor networks with linear frequency modulation. A simulated signal made through complex circuits by DRFM has higher phase noise with different patterns. To investigate the phase noise level of oscillators, a system is provided to measure the phase noise. Then, the probability of detection ( $P_{D}$ ) and the probability of false alarm ( $P_{fa}$ ) can be achieved by defining an appropriate threshold to evaluate the performance of discriminating between real targets and DRFM targets. The phase noise powers are measured through the same sets of circuits and coherent time periods in various radar sensor systems. To control the amplitude fluctuation of the received signal, the normalization of signal phase power is defined in phase noise bandwidths. The likelihood ratio test is used for target discrimination by a threshold level to achieve the minimum $P_{fa}$ of target discrimination. The proposed method has a simple structure without any additional complexities, and is easily compatible with common radar systems. Two real DRFM systems are used to evaluate the performance of the proposed method in both the L-band and X-band frequencies. The presented results are investigated in different ranges, Doppler frequencies, signal-to-noise ratios, and signal-to-jammer ratios. The experimental results prove the capability of proposed method in radar sensor networks.