CW interference effects on the performance of GPS receivers

Global Positioning System (GPS) has been widely used in electronic countermeasure field, like accurate command and precision guidance. Thus, it is necessary to find effective countermeasures to confront GPS. Radio Interference is one of the major methods in confronting the GPS in civilian and military applications. Interference signals are produced not only through all electronic systems but also illegal jammers. Among different types of interferences, continuous wave (CW) interference has strong adverse impacts on the quality of the received signal. In this paper, a system composed of receiver module, transmitter, channel module and CW interference module is established. The effects of CW interference is studied on the carrier-to-noise density ratio (C/N
₀
) of the received GPS signal as an indicator of the quality of that signal. It is analytically shown that the spectrum characteristics of the C/A code has a significant impact on the effects of CW interference. In addition, in this paper we make more detailed analysis for CW interference effects on the performance of GPS receivers. Based on the C/A code spectrum lines, the influence of CW interference on the acquisition performance of GPS receivers is further analysed and a conclusion is given as follow. When the CW interference signal has a particular frequency which is obtained according to C/A code spectrum lines, the acquisition performance is worse than other interference frequencies. This conclusion is supported by simulation results using GPS software receiver. The research on CW interference gives some theoretical gist and new thoughts on monitoring the radio noise environment and improving the anti-jamming ability of GPS receivers.