Review of Techniques to enhance the Accuracy of GNSS Receiver

Abstract

Multipath is one of the major error sources in satellite based navigation systems. Most of the satellite based navigation system works on the DS-CDMA techniques in L-band spectrum. The position of user is estimated based on the principle of Triangulation. Various position error occur in this techniques such as Dilution of Precision (DOP), Satellite and Clock error, Ephemeris error, Ionospheric error, Tropospheric error and Multipath error. All these errors have been discussed briefly. There are two major errors: Ionospheric and Multipath errors. Normally Ionospheric errors can be mitigated using Dual frequency transmission or using a suitable algorithm. Multipath error can be mitigated using various techniques such as Multipath Estimating Delay Lock Loop (MEDLL), Modified RAKE Delay Lock Loop (MRDLL), Multipath Mitigation Technology (MMT), Narrow Correlator, Double Delta technique Vision Correlator (VC), TurboDLL and others. These techniques have been discussed in detail in this paper. The technique using the Rake receiver is generally used in Communication System. It is envesaged that this technique to mitigate the multipath error significantly.