What is a cycle slip?

• A. The receiver clock fails.
• B. A cycle slip occurs when a satellite's signal is obstructed and cannot be tracked briefly.
• C. It is a permanent loss of lock.
• D. It refers to the drift of the receiver's internal oscillator.

Answer: (B)

Cycle slip is a sudden jump in the carrier-phase measurement that happens when the receiver temporarily loses the ability to track a satellite’s signal. When a satellite signal is obstructed and tracking is interrupted, the phase reference can reset by an integer multiple of a full carrier cycle, leaving the integer number of cycles unknown. Once reacquired, the receiver must re-establish that integer ambiguity.

That’s why this description fits best: a brief obstruction of the satellite signal prevents continuous phase tracking, causing a cycle slip. The other issues are different: a receiver clock problem affects time reference rather than the carrier-phase continuity; a permanent loss of lock is a complete loss of signal tracking rather than a discrete jump; and drift of the internal oscillator is a gradual change, not a sudden cycle jump in the phase.