A near-far effect canceller for GPS high sensitivity receiver

A near-far effect canceller is proposed for GPS high sensitivity receiver. It is designed to suppress the interfering signals by subtracting out their local reproduction simultaneously. Its performance depends on the accuracy of the data estimates. Furthermore, amplitude estimate is the key to the reproduction under the assumption of perfect code/carrier frequency synchronization by tracking. Two optional amplitude estimate scheme are proposed. The focus of this paper is on the near-far resistance capability. Simulation result shows that the canceller combined with two amplitude estimate scheme can suppress the interfering signal by 20dB and 30dB at least respectively. Considering of limited application, the second scheme is regarded as a candidate despite of better suppression performance. Moreover, the near-far effect canceller adopting the first amplitude estimate scheme not only improve the acquisition performance of weak satellites obviously, but also raise the maximum power level difference allowed by receiver to 38dB and improve the ability of near-far resistance by 17dB.