Dual-frequency GPS Carrier Cycle Slip Detection and Repair

Cycle slip detection and repair in dual-frequency GPS carrier phase observations represents one of the critical technologies in high-precision GNSS positioning. Cycle slips occurring in carrier phase observation data can severely impact positioning accuracy, necessitating effective detection and repair methodologies.

In dual-frequency GPS systems, phase observations from both L1 and L2 frequencies can be combined to create different observation combinations, such as wide-lane and narrow-lane combinations, to enhance cycle slip detection sensitivity. Common implementation approaches include polynomial fitting algorithms that model phase behavior over time, sliding window tests that examine consistency across consecutive epochs, and the dual-frequency Melbourne-Wübbena (MW) combination method which leverages the geometric-free linear combination of carrier phases and pseudoranges. The MW combination calculation typically involves: MW = (L1/λ1 - L2/λ2) - (P1 + P2)/(λ1 + λ2), where L represents carrier phase and P represents pseudorange measurements.

Cycle slip repair generally relies on the variation patterns of observation data across continuous epochs. Once cycle slips are accurately detected, correct integer cycle counts can be restored through phase observation continuity. Implementation often involves phase connection algorithms that compare pre- and post-slip observations, or Kalman filter-based approaches that estimate and correct cycle slips. Additionally, incorporating pseudorange observation data or utilizing multi-frequency data can further improve repair reliability by providing additional constraints for ambiguity resolution.

Efficient cycle slip detection and repair algorithms are essential for achieving high-precision kinematic positioning and Precise Point Positioning (PPP). These techniques are widely applied in surveying, seismic monitoring, and autonomous driving systems, where reliable phase data integrity is crucial for centimeter-level accuracy. Code implementations typically involve real-time processing routines that monitor phase residuals and validate cycle continuity across observation sequences.