Miniature Interferometer Terminals for Earth Surveying: Ambiguity
And Multipath with Global Positioning System
IEEE Transactions on Geoscience and Remote Sensing, (1981)DOI: 10.1109/TGRS.1981.350379
Abstract
With the recent launching of several satellites of the global positioning
system (GPS), a variety of schemes based on radio interferometry
have been proposed for the accurate determination of relative positions
of receiving terminals on the ground. Provided that the integer-cycle
ambiguities of the interferometric phase observations can be correctly
resolved, the baseline vector extending from the antenna of one terminal
to that of another should be determinable with uncertainty much smaller
than the 19-cm wavelength of the GPS transmissions. We propose a
method of ambiguity resolution that is suitable for observations
made with antennas of low directive gain. Such antennas are compact,
but the feasibility of their use has been questioned because observations
with them are susceptible to multipath interference. For short-baseline
interferometric observations of GPS our method yields correct ambiguity
resolution despite severe multipath interference and significant
sky blockage, even when instability of the frequency standards governing
the separate receiving terminals limits the time span of coherent
integration to five minutes.