Hybrid Cycle Slip Detection Method for Smartphone GNSS

Smartphone positioning is a leading GNSS research area and achieving precise positioning is highly coveted. The main roadblock to it is the erroneous Smartphone’s carrier-phase data which is highly prone to cycle slips (CS). There is a dearth of research on Cycle Slip Detection and Repair (CSDR) methods for Smartphone GNSS data. Existing literature for CSDR methods is based on carrier-phase data captured by professional grade receivers, these methods can be broadly categorized into two groups (1) Geometry-Free CSDR (GF-CSDR) and (2) Geometry-Based CSDR (GB-CSDR). It can be understood that GF-CSDR methods rely on individual satellite measurements or their linear combinations to detect CS using only single-channel data processing. On the flip side, the GB-CSDR technique performs multi-channel processing, considering the satellite-receiver geometry, which significantly affects the precision of CSDR. The proposed method will be a real-time CSDR method combining both GF and GB-CSDR. The GF-CSDR part will entail implementing a dedicated CS monitor for individual satellite’s phase data, based on the principle that the difference between the delta range derived from carrier-phase and Doppler measurements from two consecutive epochs should not exceed a certain threshold given no CS occurs. Then a GB-CSDR method based on statistical testing of the innovation sequence will be further performed as a safeguard. The rationale behind using a Doppler-based GF-CSDR rather than using other common GF-CSDR combinations e.g. Geometry Free (GF), Melbourne-Wubenna (MW), Phase-minus-Code (PMC) is that other combinations require either dual-frequency data or pseudorange measurement. Since Smartphone pseudorange data is quite noisy, its Doppler data provides a great alternative as it is comparatively precise. Additionally, the GB-CSDR method is augmented using the Doppler-based prediction technique, introduced in our previous work. The proposed algorithm’s flowchart along with preliminary results for the GF-CSDR part are shown in the provided figures.