COMPARISON OF PSEUDO-RANGE MULTIPATH EFFECTS IN A VARIETY OF GPS ANTENNA TYPES

Abstract

The GPS antenna is the connecting component between the GPS satellite and the GPS receiver. Its function is to transfer the satellite signal propagation to the receiver with minimum interruption. A satisfactory process is expected to result in an accurate and reliable performance of the GPS receiver.A multipath error is the dominant error source connected with GPS positioning. Mitigation of such errors can be achieved by better signal processing and antenna design. This paper attempts to examine the effects of the pseudo-range multipath in a variety of GPS antenna types and compare the ability of different antenna types with regards to the multipath.When the geometry between the GPS satellite and the receiver remains unchanged, a comparison study between antenna types is possible since the pseudo-range multipath pattern is repeated every sidereal day. The multipath comparison was carried out for three types of pseudo-range, the C/A code and the P-code modulated on the L1 and L2 carrier phase. The multipath pseudo-range from several satellites with different elevation angles was used in the assessment of the multipath effects. The method of comparison and the test description are also presented.Five types of GPS antennas were examined in this study. Differences in the capability of the antennas to reduce the pseudo-range multipath were detected. It is shown that a well designed antenna will assist in the mitigation of the multipath, and some geodetic antennas are less suitable for this purpose. It is also shown that ground planes play a major role in the multipath mitigation.