GNSS Multipath Reduction Using GPS and DGPS in the Real Case

Salem Titouni,Mustapha Flissi,Khaled Rouabah,Salim Atia,Oussama Khababa

doi:10.4236/pos.2017.84004

Abstract

In Global Navigation Satellite System (GNSS) like Global Positioning System (GPS) and future Galileo, space signal reception in urban environment seems to be one of most significant. The urban environment is characterized by the presence of an excessive number of obstacles that produce Multiple Path (MP) in positioning the receiver. Consequently, it is of primary importance to characterize and ameliorate the performances of GNSS receiver for this type of application. In this paper, a method to mitigate MP in GNSS applications was proposed. Its principle is based on the addition, to the geographic map of a city or a neighborhood, of a supplementary information that consists of the correction of error caused by the MPs. The latter one was carried out by the comparison of the measurements, realized by Differential GPS (DGPS) and GPS, between two different sites with the same form. The first one was characterized by the presence of the MPs and the second one was completely clear of any type of obstacle. As a consequence, the measurements comparison has allowed us to deduce the GNSS MPs errors. This information can subsequently be used to make the corrections of the errors caused by MPs and it can be generalized by a measurement company to any entire city in order to identify errors in any neighborhood.

Highlights

The first stage realized in a Global Navigation Satellite System (GNSS) receiver consists of visible satellites acquisition, as well as a coarse estimate of signal in space (SIS) parameters corresponding to each satellite of the constellation [1]
We propose a method based on actual measurements, with Global Positioning System (GPS) and Differential GPS (DGPS), for Multiple Path (MP) error correction in an urban environment
Case 1: without DGPS correction Figure 2(a): the line is determined by the dots in red, going from B1 to B20

Summary

Introduction

The first stage realized in a GNSS receiver consists of visible satellites acquisition, as well as a coarse estimate of signal in space (SIS) parameters corresponding to each satellite of the constellation [1]. The main factor that has leaded the designers of the circuits to introduce these new acquisition strategies is the use of Binary Offset Carrier (BOC) modulation [5] This recent new functionality was added to guarantee interworking between the new Galileo system and the modernized GPS by ensuring a better performance in positioning the receiver [6]. The application of these methods can lead to the loss of the positive effect of the BOC modulations on the improvement of the performances in the presence of the MP [19] [20] This last represents a propagation phenomenon which results in the presence of radio signals at the input of the receiving antenna with quite a few copies [21]. The presentation of the results some conclusions are summarized

GPS Signal in the Presence of MPs

Principle of the Proposed Method

Experimental Results

Conclusion