What is the consequence of an undetected cycle slip on carrier-phase measurements?

• A. Large, discontinuous errors in the navigation solution
• B. No effect
• C. Only affects pseudorange
• D. Improves estimation

Answer: (A)

Cycle slips happen when the receiver loses track of the carrier phase and the measured phase jumps by an unknown number of whole wavelengths. Carrier-phase observations are extremely precise, but they rely on knowing the exact integer number of cycles (the ambiguity) in addition to the fractional phase. If a slip occurs and goes undetected, that integer ambiguity becomes wrong for that epoch and can corrupt subsequent estimates as well. As a result, the navigation solution can exhibit large, abrupt changes because the phase measurement no longer matches the true geometry, injecting a strong bias into the position estimate. Detecting and correcting slips is essential to keep the solution stable.