Cycle slips detection and correction for triple-frequency GPS data

Author(s)

Caio Henrique Chrisóstomo Mendonça

• Document type: Master's Dissertation
• Press: Presidente Prudente. 2019-08-19.
• Institution: Universidade Estadual Paulista (Unesp). Faculdade de Ciências e Tecnologia. Presidente Prudente
• Defense date: 2019-04-26
• Advisor: Daniele Barroca Marra Alves

Abstract

Carrier phase observable are used in high accuracy positioning by global navigation satellite systems. However, the carrier phase measurement may suffer cycle slips during signal tracking. A cycle slip is a discontinuity of an integer number of cycles in the phase observable, caused by a temporary loss of lock in the receiver carrier tracking loop. Thus, cycle slips must be detected and corrected in order to obtain accurate positioning. Several methods were developed for this purpose. Something that has also been studied is the detection of cycle slip in the new GPS signals. The advent of the third frequency available from the GPS modernization. Should be explored in the context of cycle slip detection and correction. In the present research the different cycle slip detection and correction methods were studied and t the most suitable for the high accuracy positioning in Brazil was implemented. Two methodologies were selected for the purpose of this research, the first one based on the classical triple difference (TD) method and the second based on the linear combination sequence method. In addition, a third methodology was proposed to improve the TD method. Two experiments were performed, the first one being carried out with simulated data and the second with real data in the period of high ionospheric activity, and for both cases two scenarios were considered: short baseline and long baseline. For simulated short baseline data, the classical TD method, the proposed TD method and the linear combination sequence method presented 100%, 99.91% and 100% accuracy in the detection, resulting in 99.91%, 99.88% and 100% accuracy in the correction of cycle slips, respectively. For the simulated long baseline data, 31.37%, 63.79% and 100% of detection accuracy were obtained, resulting in 49.45%, 95.32% and 100% accuracy in the correction of cycles slips when using the classical TD method, the proposed TD method and the linear combination sequence method, respectively. In the second experiment, conducted with real data, it was possible to evaluate only the improvement in the positioning, being this for short baseline, of 81.71%, 67.08% and 10.79% for the classical TD method, the proposed TD method and linear combination sequence method, respectively. In the long baseline, after correction, the classical TD method obtained a worsening of 12.18%, the proposed TD method provided an improvement of 40.63%, whereas the linear combination sequence method could not show evaluated. (AU)

• FAPESP's process: 16/26000-5 - Cycle slips detection and correction for triple-frequency GPS data
• Grantee: Caio Henrique Chrisóstomo Mendonça
• Support Opportunities: Scholarships in Brazil - Master