OCTOPUS: Multi antennae GPS/GLONASS RTK System

The use of multiple Global Navigation Satellite System (GNSS) constellations in the determination of one's Position Velocity and Time (PVT) brings several advantages such as faster startup times and convergence times, higher accuracies, and improved Dilution of Precision (DOP) values. These advantages are especially noticeable for applications where the view of the sky is partially obscured. This work focuses on combining the two fully operational GNSS constellations, the United States GPS and the Russian GLONASS in single receiver scenarios suitable for real-time applications, presenting and solving its main interoperability issues and their different implementations and finally the performance of both systems and the combined system are evaluated using both Standard Point Positioning (SPP) approach and Precise Point Positioning (PPP) approach.

Proceedings of the ISCIE International Symposium on Stochastic Systems Theory and its Applications

In this paper, the combined GPS and GLONASS Precise Point Positioning (PPP) method based on GR (GNSS Regression) model is described. The performance of the combined GPS and GLONASS PPP is assessed using observation provided by the receiver. The corresponding positioning accuracy and convergence time are compared for GPSonly and GPS/GLONASS precise point positioning. The results have indicated a significant improvement on the position convergence time although the improvement is quite dependent on the geometry improvement of the visible satellite configurations. The results also indicate a slight improvement on the positioning accuracy due to limited availability of GLONASS satellites.

2016

A tight coupling of GNSS and inertial measurements is needed for both accurate and reliable positioning. The use of Multi-GNSS is recommended to obtain a sufficient number of visible satellites in any outdoor environment. In this paper, we perform a joint GPS/ GLONASS ambiguity fixing and a tight coupling of GNSS, 3D accelerometer, 3D gyroscope, 3D magnetometer, barometer and thermometer measurements. As GLONASS uses FDMA, double difference ambiguities are no longer integer-valued. We derive a transformation for the GLONASS double difference ambiguity term, that recovers the integer property and maintains a full-rank system. The obtained transformation maps the real-valued double difference ambiguity terms into integer-valued double difference ambiguity terms and a common single difference ambiguity term, that is treated as a real-valued parameter. Low-cost GNSS antennas can not suppress multipath and, therefore, require an estimation of multipath errors. We provide a precise model ...

Earth, Planets and Space

The benefits of combined use of the GLONASS and GPS navigation satellite constellations have become obvious for applications such as open-cast mining operations and highly dynamic vehicles such as spaceplanes. Moreover, using GLONASS satellites in addition to GPS is useful for long baseline applications since it increases the numbers of satellites in common view. Japan's National Aerospace Laboratory (NAL) has been conducting feasibility studies using combined GPS/GLONASS positioning for spaceplane landing systems and the precise navigation of stratospheric airships. This paper presents the results of the first Japanese kinematic GPS/GLONASS flight test. In the test, the difference in estimated position between dual frequency GPS and single frequency GPS/GLONASS systems was found to be within a few centimeters, indicating that GLONASS carrier phase ambiguities were correctly resolved. To demonstrate the benefits of combining GLONASS with GPS navigation, an on-the-fly (OTF) test of instantaneous ambiguity resolution with a 30 degree cutoff angle was performed. The OTF performance of the combined GPS/GLONASS system was found to be similar to that of a GPS system with a cutoff angle of 10 degrees, showing that augmentation of GPS with GLONASS will be useful for highly dynamic vehicle applications.

2001

Liwen Dai received a B.Sc. and M.

— Precise Point Positioning (PPP) has been used for the last decade as a cost-effective alternative for the ordinary DGPS-Differential GPS with an estimated precision sufficient for many applications. For many years, PPP systems are mainly based on GPS system for its reliability. GLONASS's contribution in PPP techniques is limited due to fail in maintaining full constellation. As GLONASS has reached its full constellation since a few years, GLONASS-based PPP systems could be implemented independent of GPS as well as PPP systems using combined GPS/GLONASS could be investigated. PPP using single frequency receivers is a major area of interest for many engineering applications that requires high accuracy with less cost. Single frequency receivers are widely used in developing countries for many applications such as infrastructure projects. PPP precision varies based on observation type (GPS or GLONASS) and the duration of observations among other factors. This paper presents an accuracy assessment study of GLONASS-based Static-PPP using single frequency GLONASS observations from a station in Aswan city-Egypt. The observation residuals from GLONASS-based PPP are analyzed using single frequency observations. The paper also presents an evaluation study for the variability of GLONASS-based Static-PPP precision based on different observation durations.

GPS-Differential is the default positioning technique for GPS users with high cost as it requires two receivers. Precise Point Positioning (PPP) is a technique that can compute positions with a high accuracy using a single receiver. It relies on highly accurate satellite position and clock data that can be downloaded from different sources. PPP precision varies based on positioning technique (static or kinematic), observations type (single or dual frequency), constellation (GPS or GLONASS or combined GPS/GLONASS) and the duration of observations among other factors. Kinematic-PPP has many applications in fields such as; infrastructure, hydrography and precision Agriculture. This research presents feasibility study for kinematic-PPP precision based on different observations types; single and dual frequency from different constellations; GPS, GLONASS and combined GPS/GLONASS under low visibility environment conditions. Low cost kinematic PPP technique using single frequency receivers under non-ideal environment conditions could provide a precision of a few meters for Hz. coordinates and from 10m to 20 meters for Height coordinate. High cost kinematic PPP technique using dual frequency receivers could provide a precision of few centimeters for Hz. coordinates and about 50 cm or less for Height coordinate.

Sensors

For the last two decades, the American GPS and Russian GLONASS were the basic systems used in global positioning and navigation. In recent years, there has been significant progress in the development of positioning systems. New regional systems have been created, i.e., the Japanese Quasi-Zenith Satellite System (QZSS) and Indian Regional Navigational Satellite System (IRNSS). A plan to build its own regional navigation system named Korean Positioning System (KPS) was announced South Korea on 5 February 2018. Currently, two new global navigation systems are under development: the European Galileo and the Chinese BeiDou. The full operability of both systems by 2020 is planned. The paper deals with a possibility of determination of the user’s position from individual and independent global navigation satellite system (GNSS). The article is a broader concept aimed at independent determination of precise position from individual GPS, GLONASS, BeiDou and Galileo systems. It presents real...

Survey Review

The single point positioning (SPP) mode has been widely used in many fields such as vehicle navigation, Geographic Information System and land surveying. For a long period, the SPP technology mainly relies on GPS system. With the recent revitalisation of the GLONASS constellation and two newly emerging constellations of BeiDou and Galileo, it is now feasible to investigate the performance of quad-constellation integrated SPP (QISPP) with GPS, GLONASS, BeiDou and Galileo measurements. As a satellite-based positioning technology, the QISPP is expected to improve the accuracy and availability of positioning solutions due to the increased number of visible satellites and the improved satellite sky distribution. In this study, a QISPP model is presented to simultaneously process observations from all four Global Navigation Satellite System (GNSS) constellations. Datasets collected at 47 globally distributed Multi-GNSS Experiment (MGEX) stations on two consecutive days and a kinematic experimental dataset are employed to fully assess the QISPP performance in terms of positioning accuracy and availability. Given that most navigation users are using single-frequency receivers, only the observations on a single frequency are utilised. The results indicate that the QISPP improves the positioning accuracy by an average of 16, 13 and 12% using the MGEX datasets, and 43, 31 and 51% using the kinematic experimental dataset over the GPS-only case in the east, north and up components, respectively. The availability of the QISPP solutions remains 100% even for a mask elevation angle of 40°, whereas it is only 37% for the GPS-only case. All these results are achieved using geodetic-type receivers and they are possibly optimistic for users who use navigation-type receivers.

2014

Precise point positioning (PPP) technology is mostly implemented with an ambiguity-float solution. Its performance may be further improved by performing ambiguity-fixed resolution. Currently, the PPP integer ambiguity resolutions (IARs) are mainly based on GPS-only measurements. The integration of GPS and GLONASS can speed up the convergence and increase the accuracy of float ambiguity estimates, which contributes to enhancing the success rate and reliability of fixing ambiguities. This paper presents an approach of combined GPS/GLONASS PPP with fixed GPS ambiguities (GGPPP-FGA) in which GPS ambiguities are fixed into integers, while all GLONASS ambiguities are kept as float values. An improved minimum constellation method (MCM) is proposed to enhance the efficiency of GPS ambiguity fixing. Datasets from 20 globally distributed stations on two consecutive days are employed to investigate the performance of the GGPPP-FGA, including the positioning accuracy, convergence time and the time to first fix (TTFF). All datasets are processed for a time span of three hours in three scenarios, i.e., the GPS ambiguity-float solution, the GPS ambiguity-fixed resolution and the GGPPP-FGA resolution. The results indicate that the performance of the GPS ambiguity-fixed resolutions is significantly better than that of the GPS ambiguity-float solutions. In addition, the GGPPP-FGA improves the positioning accuracy by 38%, 25% and 44% and reduces the convergence time by 36%, 36% and 29% in the east, north and up coordinate components over the GPS-only ambiguity-fixed resolutions, respectively. Moreover, the TTFF is reduced by 27% after adding GLONASS observations. Wilcoxon rank sum tests and chi-square two-sample tests OPEN ACCESS are made to examine the significance of the improvement on the positioning accuracy, convergence time and TTFF.