Doppler Satellite Surveying System

The Doppler Satellite System has become an indispensable tool for the surveyor. Because of its portability, all weather capabilities, reasonable cost, and accuracies at the sub-meter level, the Doppler satellite surveying technique is increasingly being used by surveyors around the world to meet control requirements for a variety of applications. The National Geodetic Survey which has utilized Doppler positioning since 1973 has found that with improved tracking instrumentation, field operating procedures, and refinements in the data reduction programs, positional rms errors are now less than 50 cm for 40-pass solutions and 10-cm to 25-cm for differential positions. While studies are continuing to determine the limiting accuracy of the present Doppler system, improved Doppler satellite surveying using the Global Positioning System (GPS) is being researched. Preliminary studies indicate this system may be more practical and cost effective in meeting the needs of the worldwide surveying community by giving better than 10-cm accuracy within a day's observations.