Quebec City, October 27th 2006

GEOIDE Workshop (project # 31) Preliminary Results: Receiver Initial Phase Bias Calibration By Simon Banville, Rock Santerre & Marc Cocard Quebec City, October 27th 2006

Context Initial phase offsets, present for both the satellites and the receiver, cause the ambiguities to lose their integer nature.

Motivations • Understand the nature of these biases • Do they really exist? • Do they have constant values between: • Frequencies • Satellites • Epochs • Sessions • Receivers • Find the appropriate way to calibrate or eliminate these biases to perform ambiguity resolution in PPP

Methodology • Use a simulator to produce errorless observations

Methodology • Observation equations involved Carrier phase observation (m) L1 & L2 P2 Code observation (m) Geometric distance between receiver and satellite (m) known Speed of light (m/s) Receiver clock offset (s) Carrier phase wavelength (m) Carrier phase ambiguity (cy) fractional part Receiver initial phase offset (cy) Noise (m) low noise level

Methodology • Inconveniences • Presence of absolute code biases • Correlation between the receiver clock and the ambiguities • Simulator introduces errors • Other error sources (interchannel biases, temperature, etc.)

Preliminary results

Summary • Still not sure that the initial phase biases exist • The observed biases seem to drift slightly over time • Different values for L1 and L2 • Different values between sessions • Between satellites single differences seem to cancel out most of the observed biases

Thanks to the UNB team for allowing me to use their simulator

Absolute code biases dT(observed) Using P1 dT(real) P1 code bias dT(observed) Using P2 dT(real) P2 code bias The correlations influence the values of the ambiguities

Quebec City, October 27th 2006