Performance Analysis of Adaptive Bandwidth Algorithm for Optimal Signal Tracking of DGPS Reference Receiver

Abstract

To generate accurate correction data, DGPS reference receiver should have capability to minimize the error of code and carrier phase measurements provided by delay and phase lock loop. The reason is that the correction data generated by DGPS reference receiver include the measurement error, which is one of the non-common errors incapable of elimination on differential technique. Particularly the accuracy of code and carrier phase measurements is degraded by ground-based radio navigation signal and noise provoked by machines and communication equipment around DGPS reference receiver. Good examples of those are pseudolite using pulsing scheme and near-band microwave link transmitter overcoming front-end filter of DGPS reference receiver. It is generally known that the measurement accuracy is mainly affected by the thermal noise and carrier-to-noise ratio. A narrow loop noise bandwidth algorithm is desirable to reduce the measurement error due to the thermal noise. However, it degrades the performance of GPS initial synchronization such as mean acquisition time. And it restricts the loop noise bandwidth to a threshold value determined in view of the range of carrier-to-noise ratio allowed by DGPS reference receiver, so that it is difficult to optimally track GPS signal. In order to make up for the weak points of the narrow loop noise bandwidth algorithm and simultaneously minimize the error of code and carrier phase measurements, this paper applies an adaptive bandwidth algorithm to DGPS reference receiver. In this paper, it is shown that the adaptive bandwidth algorithm can provide more accurate measurements than the narrow loop noise bandwidth algorithm through comparison analysis of simulation results between the two algorithms. This paper also analyzes the effect of the carrier-to-noise ratio change on the adaptive bandwidth algorithm. Furthermore this paper carries out sensitivity analysis of the adaptive bandwidth algorithm due to estimation uncertainty of carr