Precise point positioning with GPS and Galileo broadcast ephemerides

AbstractFor more than 20 years, precise point positioning (PPP) has been a well-established technique for carrier phase-based navigation. Traditionally, it relies on precise orbit and clock products to achieve accuracies in the order of centimeters. With the modernization of legacy GNSS constellations and the introduction of new systems such as Galileo, a continued reduction in the signal-in-space range error (SISRE) can be observed. Supported by this fact, we analyze the feasibility and performance of PPP with broadcast ephemerides and observations of Galileo and GPS. Two different functional models for compensation of SISREs are assessed: process noise in the ambiguity states and the explicit estimation of a SISRE state for each channel. Tests performed with permanent reference stations show that the position can be estimated in kinematic conditions with an average three-dimensional (3D) root mean square (RMS) error of 29 cm for Galileo and 63 cm for GPS. Dual-constellation solutions can further improve the accuracy to 25 cm. Compared to standard algorithms without SISRE compensation, the proposed PPP approaches offer a 40% performance improvement for Galileo and 70% for GPS when working with broadcast ephemerides. An additional test with observations taken on a boat ride yielded 3D RMS accuracy of 39 cm for Galileo, 41 cm for GPS, and 27 cm for dual-constellation processing compared to a real-time kinematic reference solution. Compared to the use of process noise in the phase ambiguity estimation, the explicit estimation of SISRE states yields a slightly improved robustness and accuracy at the expense of increased algorithmic complexity. Overall, the test results demonstrate that the application of broadcast ephemerides in a PPP model is feasible with modern GNSS constellations and able to reach accuracies in the order of few decimeters when using proper SISRE compensation techniques.

Download Full-text

Analysis on Signal-in-Space Range Error and Positioning Accuracy of BDS-3

10.21203/rs.3.rs-1048713/v1 ◽

2021 ◽

Author(s):

Weiping Liu ◽

Bo Jiao ◽

Jinming Hao ◽

Zhiwei Lv ◽

Jiantao Xie ◽

...

Keyword(s):

Navigation System ◽

Convergence Time ◽

Asia Pacific ◽

Single Frequency ◽

Earth Orbit ◽

Positioning Accuracy ◽

Point Positioning ◽

Range Error ◽

Space Range ◽

Better Than

Abstract Being the first mixed-constellation global navigation system, the global BeiDou navigation system (BDS-3) designs new signals, the service performance of which has attracted extensive attention. In the present study, the Signal-in-space range error (SISRE) computation method for different types of navigation satellites was presented. And the differential code bias (DCB) correction method for BDS-3 new signals was deduced. Based on these, analysis and evaluation were done by adopting the actual measured data after the official launching of BDS-3. The results showed that BDS-3 performed better than the regional navigation satellite system (BDS-2) in terms of SISRE. Specifically, the SISRE of the BDS-3 medium earth orbit (MEO) satellites reached 0.52 m, slightly inferior compared to 0.4 m from Galileo, marginally better than 0.57 m from GPS, and significantly better than 2.33 m from GLONASS. And the BDS-3 inclined geostationary orbit (IGSO) satellites achieved the SISRE of 0.90 m, on par with that of the QZSS IGSO satellites. However, the average SISRE of BDS-3 geostationary earth orbit (GEO) satellites was 1.15 m, which was marginally inferior to that of the QZSS GEO satellite (0.91m). In terms of positioning accuracy, the overall three-dimensional single-frequency standard point positioning (SPP) accuracy of BDS-3 B1C, B2a, B1I, and B3I gained an accuracy level better than 5 m. Moreover, the B1I signal exhibited the best positioning accuracy in the Asian-Pacific region, while the B1C signal set forth the best positioning accuracy in the other regions. Owing to the advantage in signal frequency, the dual-frequency SPP accuracy of B1C+B2a surpassed that of the transitional signal of B1I+B3I. Since there are more visible satellites in Asia-Pacific, the positioning accuracy of BDS-3 was moderately superior to that of GPS. The precise point positioning (PPP) accuracy of BDS-3 B1C+B2a or B1I+B3I converged to the order of centimeters, marginally inferior to that of the GPS L1+L2. However, these three combinations had a similar convergence time of approximately 30 minutes.

Download Full-text

Triple-Frequency Combining Observation Models and Performance in Precise Point Positioning Using Real BDS Data

IEEE Access ◽

10.1109/access.2019.2918987 ◽

2019 ◽

Vol 7 ◽

pp. 69826-69836

Author(s):

Honglei Qin ◽

Peng Liu ◽

Li Cong ◽

Wanqing Ji

Keyword(s):

Precise Point Positioning ◽

Triple Frequency ◽

Point Positioning ◽

And Performance

Download Full-text

Performance Analysis of Static Precise Point Positioning Using Open-Source GAMP

Artificial Satellites ◽

10.2478/arsa-2020-0004 ◽

2020 ◽

Vol 55 (2) ◽

pp. 41-60

Author(s):

Jabir Shabbir Malik

Keyword(s):

Performance Analysis ◽

Open Source ◽

Observational Data ◽

Precise Point Positioning ◽

Three Dimensional ◽

Satellite System ◽

International Gnss Service ◽

Positioning Accuracy ◽

Position Accuracy ◽

Point Positioning

AbstractIn addition to Global Positioning System (GPS) constellation, the number of Global Navigation Satellite System (GLONASS) satellites is increasing; it is now possible to evaluate and analyze the position accuracy with both the GPS and GLONASS constellation. In this article, statistical analysis of static precise point positioning (PPP) using GPS-only, GLONASS-only, and combined GPS/GLONASS modes is evaluated. Observational data of 10 whole days from 10 International GNSS Service (IGS) stations are used for analysis. Position accuracy in east, north, up components, and carrier phase/code residuals is analyzed. Multi-GNSS PPP open-source package is used for the PPP performance analysis. The analysis also provides the GNSS researchers the understanding of the observational data processing algorithm. Calculation statistics reveal that standard deviation (STD) of horizontal component is 3.83, 13.80, and 3.33 cm for GPS-only, GLONASS-only, and combined GPS/GLONASS PPP solutions, respectively. Combined GPS/GLONASS PPP achieves better positioning accuracy in horizontal and three-dimensional (3D) accuracy compared with GPS-only and GLONASS-only PPP solutions. The results of the calculation show that combined GPS/GLONASS PPP improves, on an average, horizontal accuracy by 12.11% and 60.33% and 3D positioning accuracy by 10.39% and 66.78% compared with GPS-only and GLONASS-only solutions, respectively. In addition, the results also demonstrate that GPS-only solutions show an improvement of 54.23% and 62.54% compared with GLONASS-only PPP mode in horizontal and 3D components, respectively. Moreover, residuals of GLONASS ionosphere-free code observations are larger than the GPS code residuals. However, phase residuals of GPS and GLONASS phase observations are of the same magnitude.

Download Full-text

GPS AND GLONASS COMBINED STATIC PRECISE POINT POSITIONING (PPP)

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprs-archives-xli-b1-483-2016 ◽

2016 ◽

Vol XLI-B1 ◽

pp. 483-488 ◽

Cited By ~ 1

Author(s):

D. Pandey ◽

R. Dwivedi ◽

O. Dikshit ◽

A. K. Singh

Keyword(s):

Precise Point Positioning ◽

Rapid Development ◽

Three Dimensional ◽

Global Navigation Satellite Systems ◽

Open Pit ◽

Positioning Accuracy ◽

Dilution Of Precision ◽

Satellite Visibility ◽

Point Positioning ◽

Gps Observations

With the rapid development of multi-constellation Global Navigation Satellite Systems (GNSSs), satellite navigation is undergoing drastic changes. Presently, more than 70 satellites are already available and nearly 120 more satellites will be available in the coming years after the achievement of complete constellation for all four systems- GPS, GLONASS, Galileo and BeiDou. The significant improvement in terms of satellite visibility, spatial geometry, dilution of precision and accuracy demands the utilization of combining multi-GNSS for Precise Point Positioning (PPP), especially in constrained environments. Currently, PPP is performed based on the processing of only GPS observations. Static and kinematic PPP solutions based on the processing of only GPS observations is limited by the satellite visibility, which is often insufficient for the mountainous and open pit mines areas. One of the easiest options available to enhance the positioning reliability is to integrate GPS and GLONASS observations. This research investigates the efficacy of combining GPS and GLONASS observations for achieving static PPP solution and its sensitivity to different processing methodology. Two static PPP solutions, namely standalone GPS and combined GPS-GLONASS solutions are compared. The datasets are processed using the open source GNSS processing environment <i>gLAB</i> 2.2.7 as well as <i>magicGNSS</i> software package. The results reveal that the addition of GLONASS observations improves the static positioning accuracy in comparison with the standalone GPS point positioning. Further, results show that there is an improvement in the three dimensional positioning accuracy. It is also shown that the addition of GLONASS constellation improves the total number of visible satellites by more than 60% which leads to the improvement of satellite geometry represented by Position Dilution of Precision (PDOP) by more than 30%.

Download Full-text

GPS/BDS-2/Galileo Precise Point Positioning Ambiguity Resolution Based on the Uncombined Model

Remote Sensing ◽

10.3390/rs12111853 ◽

2020 ◽

Vol 12 (11) ◽

pp. 1853

Author(s):

Jin Wang ◽

Guanwen Huang ◽

Qin Zhang ◽

Yang Gao ◽

Yuting Gao ◽

...

Keyword(s):

Ambiguity Resolution ◽

Precise Point Positioning ◽

Three Dimensional ◽

Convergence Time ◽

Wide Lane ◽

3D Positioning ◽

System Bias ◽

Point Positioning ◽

Raw Observations ◽

Gps Observations

In this study, an uncombined precise point positioning (PPP) model was established and was used for estimating fractional cycle bias (FCB) products and for achieving ambiguity resolution (AR), using GPS, BDS-2, and Galileo raw observations. The uncombined PPP model is flexible and efficient for positioning services and generating FCB. The FCBs for GPS, BDS-2, and Galileo were estimated using the uncombined PPP model with observations from the Multi-GNSS Experiment (MGEX) stations. The root mean squares (RMSs) of the float ambiguity a posteriori residuals associated with all of the three GNSS constellations, i.e., GPS, BDS-2, and Galileo, are less than 0.1 cycles for both narrow-lane (NL) and wide-lane (WL) combinations. The standard deviation (STD) of the WL combination FCB series is 0.015, 0.013, and 0.006 cycles for GPS, BDS-2, and Galileo, respectively, and the counterpart for the NL combination FCB series is 0.030 and 0.0184 cycles for GPS and Galileo, respectively. For the BDS-2 NL combination FCB series, the STD of the inclined geosynchronous orbit (IGSO) satellites is 0.0156 cycles, while the value for the medium Earth orbit (MEO) satellites is 0.073 cycles. The AR solutions produced by the uncombined multi-GNSS PPP model were evaluated from the positioning biases and the success fixing rate of ambiguity. The experimental results demonstrate that the growth of the amount of available satellites significantly improves the PPP performance. The three-dimensional (3D) positioning accuracies associated with the PPP ambiguity-fixed solutions for the respective only-GPS, GPS/BDS-2, GPS/Galileo, and GPS/BDS-2/Galileo models are 1.34, 1.19, 1.21, and 1.14 cm, respectively, and more than a 30% improvement is achieved when compared to the results related to the ambiguity-float solutions. Additionally, the convergence time based on the GPS/BDS-2/Galileo observations is only 7.5 min for the ambiguity-fixed solutions, and the results exhibit a 53% improvement in comparison to the ambiguity-float solutions. The values of convergence time based on the only-GPS observations are estimated as 22 and 10.5 min for the ambiguity-float and ambiguity-fixed solutions, respectively. Lastly, the success fixing rate of ambiguity is also dramatically raised for the multi-GNSS PPP AR. For example, the percentage is approximately 99% for the GPS/BDS-2/Galileo solution over a 10 min processing period. In addition, the inter-system bias (ISB) between GPS, BDS-2, and Galileo, which is carefully considered in the uncombined multi-GNSS PPP method, is modeled as a white noise process. The differences of the ISB series between BDS-2 and Galileo indicate that the clock datum bias of the satellite clock offset estimation accounts for the variation of the ISB series.

Download Full-text

A PROTOTYPE TRACK-FINDING PROCESSOR FOR THE LEVEL-1 TRIGGER OF THE CMS ENDCAP MUON SYSTEM

International Journal of Modern Physics A ◽

10.1142/s0217751x01009259 ◽

2001 ◽

Vol 16 (supp01c) ◽

pp. 1178-1180

Author(s):

S. M. WANG ◽

D. ACOSTA ◽

A. MADORSKY ◽

B. SCURLOCK ◽

A. ATAMANCHUK ◽

...

Keyword(s):

Three Dimensional ◽

High Density ◽

Fringe Field ◽

Test Results ◽

Muon System ◽

Cathode Strip ◽

Level 1 ◽

Sram Memory ◽

And Performance

We report on the development and performance of a novel track-finding processor for the Level-1 trigger of the CMS endcap muon system. The processor links track segments identified in the cathode-strip chambers of the endcap muon system into complete three-dimensional tracks. It then measures the momentum of the best track candidates from the sagitta measured between three muon chambers in the endcap fringe field. The processor is pipelined at 40 MHz, and has an overall latency of 400 ns. The logic for the prototype is implemented in high-density FPGAs and SRAM memory. It receives approximately 3 gigabytes of data every second from a custom backplane operating at 280 MHz. Test results of the prototype are consistent with expectation.

Download Full-text

Enabling robust and accurate navigation for UAVs using real-time GNSS precise point positioning and IMU integration

The Aeronautical Journal ◽

10.1017/aer.2020.80 ◽

2020 ◽

Vol 125 (1283) ◽

pp. 87-108

Author(s):

C. Chi ◽

X. Zhan ◽

S. Wang ◽

Y. Zhai

Keyword(s):

Real Time ◽

Precise Point Positioning ◽

Three Dimensional ◽

Coupled System ◽

Measurement Unit ◽

Satellite Geometry ◽

Tightly Coupled ◽

Point Positioning ◽

Gnss Measurements ◽

The One

ABSTRACTAccurate navigation is required in many Unmanned Aerial Vehicle (UAV) applications. In recent years, GNSS Precise Point Positioning (PPP) has been recognised as an efficient approach for providing precise positioning services. In contrast to the widely used Real-Time Kinematic (RTK), PPP is independent of reference stations, which greatly broadens its scope of application. However, the accuracy and reliability of PPP can be significantly decreased by poor GNSS satellite geometry and outage. In response, a real-time four-constellation GNSS PPP is applied to improve the geometry in this work, and PPP is tightly coupled with an Inertial Measurement Unit (IMU) to smooth the position and velocity output, thus improving the robustness of the navigation solution. Experimental flight tests are carried out using a UAV in an open-sky area, and GNSS-challenged environments are simulated. The results show that the four-constellation GNSS PPP/IMU integration reduces the Root-Mean-Square (RMS) Three-Dimensional (3D) positioning and velocity error by 76.4% and 67.1%, respectively, in open sky with respect to the one-GNSS PPP. Under scenarios where GNSS measurements are insufficient, the coupled system can still provide continuous solutions. Moreover, the coupled PPP/IMU system can also maintain the convergence of PPP during GNSS-challenged periods and can greatly shorten the re-convergence period of PPP when the UAV returns to the open sky.

Download Full-text

Study on Multi-GNSS Precise Point Positioning Performance with Adverse Effects of Satellite Signals on Android Smartphone

Sensors ◽

10.3390/s20226447 ◽

2020 ◽

Vol 20 (22) ◽

pp. 6447

Author(s):

Hongyu Zhu ◽

Linyuan Xia ◽

Dongjin Wu ◽

Jingchao Xia ◽

Qianxia Li

Keyword(s):

Adverse Effects ◽

Precise Point Positioning ◽

Phase Error ◽

Three Dimensional ◽

Satellite System ◽

Dual Frequency ◽

Positioning Accuracy ◽

Noise Ratio ◽

Point Positioning ◽

Gnss Observations

The emergence of dual frequency global navigation satellite system (GNSS) chip actively promotes the progress of precise point positioning (PPP) technology in Android smartphones. However, some characteristics of GNSS signals on current smartphones still adversely affect the positioning accuracy of multi-GNSS PPP. In order to reduce the adverse effects on positioning, this paper takes Huawei Mate30 as the experimental object and presents the analysis of multi-GNSS observations from the aspects of carrier-to-noise ratio, cycle slip, gradual accumulation of phase error, and pseudorange residual. Accordingly, we establish a multi-GNSS PPP mathematical model that is more suitable for GNSS observations from a smartphone. The stochastic model is composed of GNSS step function variances depending on carrier-to-noise ratio, and the robust Kalman filter is applied to parameter estimation. The multi-GNSS experimental results show that the proposed PPP method can significantly reduce the effect of poor satellite signal quality on positioning accuracy. Compared with the conventional PPP model, the root mean square (RMS) of GPS/BeiDou (BDS)/GLONASS static PPP horizontal and vertical errors in the initial 10 min decreased by 23.71% and 62.06%, respectively, and the horizontal positioning accuracy reached 10 cm within 100 min. Meanwhile, the kinematic PPP maximum three-dimensional positioning error of GPS/BDS/GLONASS decreased from 16.543 to 10.317 m.

Download Full-text