What is RTCM?
A. The correct name is RTCM-104, Version 2 or 2.1. The acronym stands for Radio Technical Committee, Marine and is the name of a committee that governs standards for passing data between different equipment used in the Marine Electronics Industry. In the early days of Differential GPS, they set up a standard format for sending differential correction data to a GPS receiver. The actual format is complex and lengthy, but it contains three main elements: (1) The time of the measurement at the Base Station, (2) measured range errors (Corrections) for every satellite in view at that Base Station, and (3) the “range error rate” for every satellite in view. As explained above, the Range Rate term is currently set to a zero value. If SA were to be turned back ON, the rate term would be measured and sent in every message.
