Positioning with a GPS Pseudorange Receiver

Schriftenreihe
des Instituts für Geodäsie

Heft 20-2/1985


 
Positioning with a GPS Pseudorange Receiver
-  Functional Model Test Results  -

Bodo E. GERLACH
Prakla-Seismos GmbH, Hannover

 

In: WELSCH, Walter M. / LAPINE, Lewis A. (Hrsg.) [1985]:
International Federation of Surveyors - FIG -
Proceedings Inertial, Doppler and GPS Measurements for National and Engineering Surveys
Joint Meeting of Study Groups 5B and 5C, July 1-3, 1985

Schriftenreihe Universitärer Studiengang Vermessungswesen, Universität der Bundeswehr München, Heft 20-2, Neubiberg, S. 315-336.
 



Abstract

Accurate, reliable, and economical positioning is an essential requirement in geophysical exploration. Hence it is evident for PRAKLA-SEISMOS GMBH, Hannover, as a contractor in geophysical exploration, to solve the problem of positioning in land-, sea-, and air-operations.

Starting with the development of a GPS receiver for navigation purposes in 1981 measurements have been made with functional models of the developed GPS receiver to examine the possibilities of GPS positioning for geophysical land-operations.

There are different GPS receiver structures and measurement methods. The structure and the measurement method of the PRAKLA-SEISMOS GPS receiver, developed in a joint venture with Kongsberg Våpenfabrikk, Norway, is presented. To this day many tests have been carried out with two functional models, proving the accuracy and reliability of the developed receiver. The test equipment has been installed in a car consisting of one GPS receiver, cassette drives, an electronic chart showing on-line the calculated positions and a desktop computer for off-line computations. Desired relative accuracies of 1 m - 3 m can be reached in 2 - 3 min. time; this is theoretically shown with an error budget and, in practice, with measurements. Results of differential measuring with two functional models are also presented.

Accurate and reliable positioning may be influenced by shadowing from buildings, trees etc., by single reflector multipath effects or electromagnetic disturbances. An analysis of the influence of the three types of disturbances points out that shadowing is the main problem and restricts the application of GPS in land positioning.

Last but not least, the results of the measurement lead to a discussion if or under which conditions a GPS positioning is economical in geophysical land-operations.
 



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