GPS Satellite Surveying, 4th Edition

6.2 Operational Details

Whether one develops and improves positioning algorithms, uses GNSS to support research activities, or runs commercially available receivers in engineering applications, there are a number of operational details that one should know. It also helps to know that a lot of what might be called the GNSS infrastructure is in place and ready to be tapped. We begin with some topics of interest to developers of processing techniques and then talk about services that are mostly free of charge and available to the common user.

We briefly address the issue of computing the topocentric satellite distance the GNSS signal travels from the time of emission at the satellite to reception at the user receiver antenna. Detailed information is given on the timing group delay, satellite clock correction, and intersignal corrections, all three of which are transmitted by the navigation message. We then briefly discuss cycle slips in the carrier phase observable, the phase windup correction resulting from the right-circular polarized nature of the signals, and the “ever-present” multipath. Our discussion on service begins with relative and absolute antenna calibration provided specifically by the National Geodetic Service, and continues with a discussion of the International GNSS Service, its products, and online computing series.

6.2.1 Computing the Topocentric Range

The pseudorange equation (6.1.28) and the carrier phase equation (6.1.30) require computation of the topocentric ...