On jamming GPS signals

The mean time to lose lock (MTLL) of tracking loop has recently attracted much attention. Analytic expressions for the leading terms of the MTLL of first and second PN code tracking loops have been obtained. In most works it is assumed that the system is excited by white noise. However it is well known that generally the noise observed from a GPS receiver is correlated. Therefore an analysis of coloured noise is important for GPS receivers. We present a solution for the MTLL, of a first order PN coherent tracking loop in the case where the system is excited by coloured noise with small intensity. We show that for a fixed jammer power there is an optimal jammer bandwidth, and therefore a wideband jammer is superior to a single-tone jammer with the same power. The results are used for practical jammer design. The jammer power is determined to attain desired MTLL for a given receiver bandwidth and velocity.