Performance assessment of GPS/GLONASS single point positioning in an urban environment

Abstract

In signal-degraded environments such as urban canyons and mountainous area, many GNSS signals are either blocked or strongly degraded by natural and artificial obstacles. In such scenarios standalone GPS is often unable to guarantee a continuous and accurate positioning due to lack (or the poor quality) of signals. The combination of different GNSSs could be a suitable approach to fill this gap, because the multi-constellation system guarantees an improved satellite availability compared to standalone GPS, thus providing enhanced accuracy, continuity and integrity of the positioning. The present GNSSs are GPS, GLONASS, Galileo and Beidou, but the latter two are still in the development phase. In this work GPS/GLONASS systems are combined for single point positioning and their performance are assessed for different configurations. Using GPS/GLONASS multi-constellation implies the addition of an additional unknown, i.e. the intersystem time scale offset, which requires a sacrifice of one measurement. Since the intersystem offset is quasi-constant over a short period, a pseudo-measurement can be introduced to compensate the sacrifice.The benefit after adding a pseudo-measurement has been demonstrated in a vehicular test.

GNSS Signals Acquisition and Tracking in Unfavorable Environment

“…In addition, in [45] the combined GPS-Galileo navigation solution has been assessed providing slight improvements with respect to the standalone GPS. In addition, the results presented in [43] confirm that the GPS/GLONASS combination, reduced to only four combined satellites, shows apparent improvements compared to GPS-only solution in terms of availability and accuracy.…”

“…Accordingly, many research efforts have been aimed at the development, implementation and design of MC/MF-GNSS software and hardware defined receivers. Nevertheless, it should be noted that MC systems introduce an additional unknown to the estimation procedure due to the offset between their time scales [43]. Accordingly, the required number of visible satellites increases [43].…”

“…Nevertheless, it should be noted that MC systems introduce an additional unknown to the estimation procedure due to the offset between their time scales [43]. Accordingly, the required number of visible satellites increases [43]. To resolve this problem, an algorithm has been proposed in [44] to obtain a position solution with only four visible GPS/GLONASS satellites.…”

Reliability analysis of the results of RTN GNSS surveys of building structures using indirect methods of measurement

“…A need to implement the third satellite system GALILEO and the modernization of the existing systems was already introduced in the year 2000 by (Gunter, 2000). A necessity of combining different GNSS systems is also emphasized by (Angrisano et al, 2013). They prove that such an action is the most desirable, as the multi-constellation system ensures a better satellite availability compared to GPS only, thereby providing for a greater accuracy, continuity and integrity of positioning.…”

Mathematical Analysis of the Algorithms Used in Modernized Methods of Building Measurements With RTN GNSS Technology

“…The issue of measuring control points has been presented in detail in (Krzyżek et al, 2014b) An additional factor favorably affecting the accuracy, continuity and integrity of positioning, as well as the efficiency and precision of the captured results, both in the conditions with the obscured and clear horizon, is the application of a multi-constellation system (GPS, GLONASS), which has been demonstrated and proven in the research studies, (Angrisano et al, 2013) and (Pirti et al, 2013).…”