A. N. Podkorytov

Methods of estimation and compensation for systematic biases in pseudorange and pseudophase measurements are analyzed in this article. Following effects are considered: relativistic effects, wind-up effects, troposphere and ionosphere signal path delays, phase center offsets, phase center variations and tidal displacements (ocean loading, polar motion, solid Earth tides, atmospheric loading). Positioning accuracy level for a number of important applications (such as precise point positioning (PPP), orbit determination and time synchronization (ODTS) and so on) is directly connected to an accuracy of mathematical models for pseudorange and pseudophase measurements. This is the reason of significance of precise mathematical models for pseudorange and pseudophase measurements. In scientific publications the author of the article has found a number of mathematical models which can be used for estimation of different biases in pseudorange and pseudophase measurements. Some equations for these models are shown in the article, and more detailed equations can are described in references. For test purposes some computing experiments were performed. These experiments were connected to precise point positioning tests using corrected pseudophase and pseudorange measurements and precise ephemerides from International GNSS Service (IGS). At the same time initial measurement data were processed by several international services (APPS (USA), GAPS (Canada), magicGNSS (Spain), NRCan (Canada)). Comparative results are shown in the article. Achievable positioning accuracy in PPP tests is about 1 centimeter in post-processing mode. According to these test results mathematical models for pseudorange and pseudophase measurements described in this article can be considered as good mathematical models of these measurements for practical purposes.