Online Journal of Space Communication


A third civil frequency at 1176.45MHz will be added to the GPS system.
QZSS (Quasi Zenith Satellite System) proposed by Japan will also have the
new signal. This new frequency and the advent of QZSS will greatly enhance
the accuracy, reliability and robustness of civilian GPS receivers. One of these
enhancements is that it is possible to determine the GPS phase ambiguities
more or less instantaneously. This performance will have a tremendous impact
on navigation. In this paper, the possibility of precise positioning in the urban
area is examined from a point of instantaneous ambiguity resolution.
A typical QZSS constellation, a third civil frequency and
ambiguity_estimation for triple-frequency data is discussed. The simulator for
precise positioning includes multipath effect which has been developed is also
discussed. To reflect multipath effect, the following points are considered:
Building reflection, building diffraction, ground reflection, antenna pattern, and
correlator selection. It is confirmed that a third civil frequency could make it
much easier to resolve ambiguities more quickly and the advent of QZSS helps
to increase visible satellites in the urban area (Asian area). Although next
generation satellite positioning system doesn’t provide perfect navigation,
improved performance could be realized.



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