负SNR数字调相信号的干涉仪测向技术

传统意义上的干涉仪测向数学模型与处理流程一般要求目标信号具有正信噪比(SNR),在对负SNR调制信号实施测向时通常会产生较大误差甚至失效。在分析传统方法失效原因的基础上,利用数字调相信号的特点,通过非线性变换对负SNR信号进行高次载波恢复,然后针对恢复后的高次载波进行相位差提取,从而获得被测信号的来波方向。在此基础上对该方法所能达到的精度进行了理论分析,并将其推广至凡是具有可恢复载波分量的测向应用情况。仿真结果验证了该方法的有效性,这对于干涉仪在电子侦察和电磁频谱监测中更加广泛的应用提供了新的参考。

Direction finding using interferometer for digital phase-modulated signal with negative SNR

The signal with positive SNR (Signal-to-Noise Ratio) is required for the mathematic model and processing flow of the interferometer in traditional direction finding method. But the large error or invalidation of the model usually occurs, when it is used for the modulated signal with negative SNR. After the reason is analyzed, the characteristic of the digital phase-modulated signal is utilized and the high-order carrier wave is recovered through the non-linear transform. Then direction finding is completed based on the phase difference measurement for recovered high-order carrier, and the precision of this method is theoretically discussed.Finally, the method is generalized for the condition that the carrier element can be recovered from the measured signals in direction finding applications. Its validity is demonstrated through simulation,which provides a new reference for applying the interferometer more widely in the electronic reconnaissance and electromagnetic spectrum surveillance.