Implementation and Performance of Clock Steering in a Software GPS L1 Single Frequency Receiver

Abstract

ABSTRACT: This paper implements clock steering in a software GPS receiver that maintains the receiver time with a certain range from the GPS time (GPST) and reports the position/measurements on integer seconds. Recognizing that the essence of clock steering is to estimate the true sampling frequency of the receiver, this estimation could be done by using either the code or carrier phase measurements. Therefore, the quality of the code and carrier phase measurements becomes significant. The detailed algorithms for generating those two measurements in a software GPS receiver are presented. The quality of the algorithms is evaluated through the validation of the single point and carrier phase differential position solutions. The clock steering algorithms based on both the code and carrier phase are then presented and evaluated. Test results show that when the steering option is turned on, the remaining clock errors in the receiver measurements are less than 50 ns.