Activities of the Institut Géographique National (I.G.N.) in the field of Doppler satellite geodesy

Abstract

The Institut Géographique National (I.G.N.), the French national geodetic and mapping agency, started in 1974 a research and development programme on Doppler satellite techniques, in order to determine their accuracy and capabilities, to investigate possible geodetic uses and to establish various operational positioning methods, according to a cost: precision ratio. A review is given to the current (1978) status and investigations planned for instrumentation and field facilities, modelling and data processing techniques, and geodetic applications. As a general result from several comparisons, the precision of position computed with the I.G.N. software (gdp) is 3 m for single point positioning (s.p.p.) with the use of broadcast ephemerides (option I), and 1 m with s.p.p. with DMA precise ephemerides (option II) and short arc positioning (option III). Present investigations seem to indicate that the precision of option II can be improved to a few decimetres, whereas option III in its present formulation has some limitations.