Cycle Slip Detection and Repair for Dual-Frequency LEO Satellite GPS Carrier Phase Observations with Orbit Dynamic Model Information

Hui Wei,Jiancheng Li,Shoujian Zhang,Xinyu Xu

doi:10.3390/rs11111273

Abstract

Cycle slip detection and repair are crucial for precise GPS-derived orbit determination of the low-Earth orbit (LEO) satellites. We present a new approach to detect and repair cycle slips for dual-frequency LEO satellite GPS observations. According to Newton’s equation of motion, the second-order time difference of the LEO satellite’s position (STP) is only related to the sampling interval and the satellite’s acceleration, which can be precisely obtained from the known orbit dynamic models. Then, several kinds of second-order time-difference geometry-free (STG) phase combinations, taking full advantage of the correlation between the satellite orbit variations and the dynamic model, with different level of ionospheric residuals, are proposed and adopted together to detect and fix cycle slips. The STG approach is tested with some LEO satellite GPS datasets. Results show that it is an effective cycle slip detection and repair method for LEO satellite GPS observations. This method also has some important features. Firstly, the STG combination is almost independent of the pseudorange. Secondly, this method is effective for LEO satellites, even in real-time application. Thirdly, this method is suitable for ground-based GPS receivers if we know the acceleration of the receivers.

Highlights

As GPS carrier phase observations are much more accurate than pseudorange observations, carrier phase measurements are usually used as observations for the precise GPS-derived orbit determination of low-Earth orbit (LEO) satellites [1,2,3,4,5]
In order to investigate the performance of the proposed second-order time-difference geometry-free (STG) cycle slip detection and repair method, the analysis of our paper is based on the GPS products (provided by the International GNSS Service (IGS)), LEO precise orbit products (GOCE, GRACE-A, and Jason-3 satellites provided by the European Space Agency (ESA), Jet Propulsion Laboratory (JPL), and CNES, respectively), and GOCE satellite GPS observations provided by the ESA
With the GPS/LEO satellite acceleration derived from known orbit dynamic models, the geometric variations in GPS carrier phase observations can be removed

Summary

Introduction

As GPS carrier phase observations are much more accurate than pseudorange observations, carrier phase measurements are usually used as observations for the precise GPS-derived orbit determination of low-Earth orbit (LEO) satellites [1,2,3,4,5]. Compared to ground GPS data, due to the high-speed motion and complicated observation environment of LEO satellites, cycle slips occur frequently in LEO satellite GPS carrier phase data, which are undesirable and must be detected and repaired correctly to maintain the continuity of GPS carrier phase observations. The difficulties of cycle slip detection are as follows: (i) the geometric distance between receiver and satellite varies greatly; (ii) the ionospheric delay varies quickly. How to eliminate the influence of geometric distance and ionospheric delay, and construct an effective quantity that is sensitive to the cycle slips is the key point of cycle slip detection. According to the strategy to eliminate the geometric distance, these methods can be divided into two categories, described below

Methods

Results

Conclusion