Frequency tracking algorithm based on adaptive fading Kalman filter

A time domain signal tracking algorithm is proposed to estimate the frequency of a chirp-type global navigation satellite system (GNSS) interference. The unknown interference frequency of GNSS in the received signal can be estimated by using the properties of the trigonometrical functions, but the thus-obtained value can have a lot of error caused by measurement noise and by the frequency change of the interference. In order to reduce the error, an adaptive fading Kalman filter that is based on the Fourier series is applied in the proposed algorithm. The performance of the tracking algorithm is verified by simple simulations and the proposed algorithm can track the frequency of interference whose the jammer-to-signal ratio (J/S) is more than 30dB, which would seriously affect the accuracy of the GNSS.