Carrier Phase Ambiguity refers to the unknown integer number of full wavelength cycles in the carrier phase measurement of a GNSS signal. This concept is crucial in high-precision GNSS-aided inertial navigation systems (INS/GNSS integration).
Since GNSS signals are transmitted as electromagnetic waves, a receiver measures the phase of the signal’s carrier wave to determine distance. However, it can only track the fractional part of the phase, leaving an integer ambiguity—the number of whole wavelengths between the satellite and receiver is unknown. Resolving this ambiguity is essential for achieving centimeter-level accuracy in positioning, which is a key feature of RTK (Real-Time Kinematic) and PPP (Precise Point Positioning) solutions.
Carrier Phase Ambiguity in INS/GNSS Integration
In inertial navigation, carrier phase ambiguity resolution is used to refine GNSS positioning data, which then aids the inertial navigation system (INS) in reducing errors, especially in long-duration operations. Since an INS alone suffers from drift over time, integrating it with ambiguity-resolved GNSS data significantly enhances position accuracy and stability.
