GNSS Cycle Slips Impact on Estimation

In Global Navigation Satellite System (GNSS) positioning, particularly when using carrier phase measurements for high precision, cycle slips represent a sudden jump in the observed phase by an integer number of cycles.

Detrimental Effect of Cycle Slips

Cycle slips are most detrimental for estimating integer ambiguity. Here's why:

• Integer Ambiguity: High-precision GNSS techniques (like RTK) rely on resolving the unknown integer number of carrier wavelengths between the satellite and receiver at the start of tracking.
• Direct Corruption: A cycle slip introduces an error equivalent to an integer number of cycles directly into the carrier phase measurement. This corrupts the raw data needed to determine the correct initial integer ambiguity.
• Consequence: If cycle slips occur and are not detected and corrected, the estimated integer ambiguities will be incorrect, leading to large position errors.

Other GNSS Error Sources

While cycle slips can indirectly affect other estimations, their primary impact is on integer ambiguity resolution:

• Receiver Clock Error: This is typically handled by the receiver's internal clock model and broadcast satellite clock corrections. Cycle slips complicate this but aren't the most direct impact.
• Multipath Error: Occurs due to signal reflections. Cycle slips don't directly cause or primarily affect multipath estimation itself.
• Atmospheric Delay: Ionospheric and tropospheric delays are modeled or estimated using dual-frequency data or external models. Cycle slips make these models less accurate but don't directly corrupt the delay measurement itself in the same way they corrupt phase counts.

Therefore, the accurate estimation of integer ambiguity is critically dependent on the absence or proper detection and correction of cycle slips in GNSS carrier phase measurements.