For certain applications, we utilize a pair of survey grade GNSS receivers manufactured by Topcon Positioning Systems, Inc. These 20-channel receivers track both the GPS (USA) and GLONASS (Russia) constellations, and include an internal Satel radio modem which can be used to provide real time corrections, for RTK work. Alternatively, these receivers can be used for “static” work, and post processed in the office for improved positioning.
Performance of these receivers is based upon a variety of factors, including the configuration of the satellite constellations at the time of work, and most importantly, whether the satellites are visible. Tree canopy, buildings, etc. can significantly limit the effectiveness of surveying with GNSS equipment.
For static or fast-static use of these receivers, the accuracy (based on a minimum of 6 GPS satellites above 15 degrees) is as follows:
Horizontal: 3 millimeters plus 0.5 parts per million times the baseline length
Vertical : 5 millimeters plus 0.5 parts per million times the baseline length
For Kinematic or RTK use, the accuracy is as follows:
Horizontal: 10 millimeters plus 1 part per million times the baseline length
Vertical : 15 millimeters plus 1 part per million times the baseline length