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To analyze the behavior characteristics of widelane fractional carrier-phase biases, time series of biases were analyzed. Single-differenced widelane fractional phase bias calibration values, involving two GPS satellites and one receiver, were analyzed for long-term characteristics between January 1, 1997, and May 30, 1998. The single differencing removes receiver effects, and differencing of the code and carrier-phase measurements isolates the widelane ambiguity. This ambiguity term includes a fraction that is consistent for each single-difference satellite pair. These fractional terms were averaged over a global tracking network using directional statistics to calculate daily fractional phase bias calibration values. Trends were then computed for individual GPS satellites. Over the test period, satellites 22, 26, 27, 29, 31, and 32 experienced near-zero drift rates in widelane and signals with amplitudes smaller than 0.1 widelane cycle. Satellites 30, 33, and 40 had high drift rates between 0.78 and 1.4 widelane cycles/year and substantial second-order signals. These groupings are correlated with mission launch date.

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