Presented at SatNav 2003

To achieve a high level of accuracy from an integrated GPS/INS system, the carrier-phase observations have to be used to update the integration filter’s states. It is a prerequisite that the integer ambiguity must be resolved before using carrier-phase measurements. However, the occurrence of an undetected cycle slip will significantly degrade the filter’s performance. In this paper, an algorithm that can effectively detect and identify cycle slips will be presented. The algorithm uses additional information provided by the INS, and applies a statistical technique known as the cumulative-sum (CUSUM) test. Cycle slip decision values can be computed from the INS predicted position due to the fact that its short-term accuracy is very high. The CUSUM test is then very sensitive to abrupt changes of mean values, making it ideal for the detection of cycle slips. Kinematic experiments were carried out in order to test the effectiveness of the proposed algorithm. The results indicate that cycle slips can be effectively detected and then instantaneously corrected using the proposed algorithm. Hence, the accuracy and performance of the integrated system can be maintained, even if cycle slips exist in the raw GPS measurements.