scholarly journals Influence of Distance between Reference Station and User Station on DGPS Positioning Accuracy

1995 ◽  
Vol 93 (0) ◽  
pp. 1-6
Author(s):  
Toshiharu KAKIHARA ◽  
Seiichi TAKEDA ◽  
Yoshinori MIYAMOTO ◽  
Akira NODA ◽  
Yuji MINE
Keyword(s):  
Reference Station ◽  
Positioning Accuracy ◽  
User Station

scholarly journals Characterization of Carrier Phase-Based Positioning in Real-World Jamming Conditions

2021 ◽  
Vol 13 (14) ◽  
pp. 2680
Author(s):  
Søren Skaarup Larsen ◽  
Anna B. O. Jensen ◽  
Daniel H. Olesen
Keyword(s):  
Real World ◽  
Carrier Phase ◽  
Reference Station ◽  
Baseline Length ◽  
Dual Frequency ◽  
Positioning Accuracy ◽  
The Impact ◽  
Single Versus ◽  
Selection Of

GNSS signals arriving at receivers at the surface of the Earth are weak and easily susceptible to interference and jamming. In this paper, the impact of jamming on the reference station in carrier phase-based relative baseline solutions is examined. Several scenarios are investigated in order to assess the robustness of carrier phase-based positioning towards jamming. Among others, these scenarios include a varying baseline length, the use of single- versus dual-frequency observations, and the inclusion of the Galileo and GLONASS constellations to a GPS only solution. The investigations are based on observations recorded at physical reference stations in the Danish TAPAS network during actual jamming incidents, in order to realistically evaluate the impact of real-world jamming on carrier phase-based positioning accuracy. The analyses performed show that, while there are benefits of using observations from several frequencies and constellations in positioning solutions, special care must be taken in solution processing. The selection of which GNSS constellations and observations to include, as well as when they are included, is essential, as blindly adding more jamming-affected observations may lead to worse positioning accuracy.

scholarly journals GPS/BDS RTK Positioning Based on Equivalence Principle Using Multiple Reference Stations

2020 ◽  
Vol 12 (19) ◽  
pp. 3178
Author(s):  
Jian Wang ◽  
Tianhe Xu ◽  
Wenfeng Nie ◽  
Guochang Xu
Keyword(s):  
Equivalence Principle ◽  
Urban Areas ◽  
Unmanned Vehicles ◽  
Global Navigation Satellite Systems ◽  
Reference Station ◽  
Unknown Parameters ◽  
Positioning Accuracy ◽  
Kinematic Positioning ◽  
Parameter Constraints ◽  
Multiple Reference

Reliable real-time kinematic (RTK) is crucially important for emerging global navigation satellite systems (GNSSs) applications, such as drones and unmanned vehicles. The performance of conventional single baseline RTK (SBRTK) with one reference station degrades greatly in dense, urban environments, due to signal blockage and multipath error. The increasing use of multiple reference stations for kinematic positioning can improve RTK positioning accuracy and availability in urban areas. This paper proposes a new algorithm for multi-baseline RTK (MBRTK) positioning based on the equivalence principle. The advantages of the solution are to keep observation independent and increase the redundancy to estimate the unknown parameters. The equivalent double-differenced (DD) observation equations for multiple reference stations are firstly developed through the equivalent transform. A modified Kalman filter with parameter constraints is proposed, as well as a partial ambiguity resolution (PAR) strategy is developed to determine an ambiguity subset. Finally, the static and kinematic experiments are carried out to validate the proposed algorithm. The results demonstrate that, compared with single global positioning system (GPS) and Beidou navigation system (BDS) RTK positioning, the GPS/BDS positioning for MBRTK can enhance the positioning accuracy with improvement by approximately (45%, 35%, and 27%) and (12%, 6%, and 19%) in the North (N), East (E), and Up (U) components, as well as the availability with improvement by about 33% and 10%, respectively. Moreover, the MBRTK model with two and three reference receivers can significantly increase the redundancy and provide smaller ambiguity dilution of precision (ADOP) values. Compared with the scheme-one and scheme-two for SBRTK, the MBRTK with multiple reference receivers have a positioning accuracy improvement by about (9%, 0%, and 6%) and (9%, 16%, and 16%) in N, E, and U components, as well as the availability improvement by approximately 10%. Therefore, compared with the conventional SBRTK, the MBRTK can enhance the strength of the kinematic positioning model as well as improve the positioning accuracy and availability.

scholarly journals Improving the Stochastic Model for VRS Network-Based GNSS Surveying

2019 ◽  
Vol 54 (1) ◽  
pp. 17-30 ◽  
Author(s):  
Thanate Jongrujinan ◽  
Chalermchon Satirapod
Keyword(s):  
Stochastic Model ◽  
Covariance Matrix ◽  
Ambiguity Resolution ◽  
Reference Station ◽  
Double Difference ◽  
Atmospheric Effects ◽  
Equal Weight ◽  
Virtual Reference ◽  
Positioning Accuracy ◽  
Variance Covariance Matrix

Abstract The VRS network-based technique has become the main precise GNSS surveying method especially for medium-range baselines (approximately 20-70 km). The key concept of this approach is to use the observables of multiple reference stations to generate the network correction in the form of a virtual reference station for mitigating distance-dependent errors including atmospheric effects and orbital uncertainty at the user’s location. Numerous GNSS data processing strategies have been adopted in the functional model in order to improve both the positioning accuracy and the success of ambiguity resolution. However, it is impossible to completely model the aforementioned errors. As a result, the unmodelled residuals still remain in the virtual reference station observables when the least squares estimation is employed. An alternative approach to deal with these residuals is to construct a more realistic stochastic model whereby the variance-covariance matrix is assumed to be homoscedastic. This research aims to investigate a suitable stochastic model used for the VRS technique. The rigorous statistical method, MINQUE has been applied to estimate the variance-covariance matrix of the double-difference observables for a virtual reference station to rover baseline determination. The findings of the comparison to the equal-weight model and the satellite elevation-based model indicated that the MINQUE procedure could enhance the positioning accuracy. In addition, the reliability of ambiguity resolution is also improved.

scholarly journals A Virtualization Approach to Correct Systematic Errors in Measured TDOA and FDOA for Low Orbit Dual-Satellite Positioning Systems

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Gang Li ◽  
Min Zhou ◽  
Hongwen Tang ◽  
Hongbin Chen
Keyword(s):  
Systematic Errors ◽  
Time Difference ◽  
Frequency Difference ◽  
Reference Station ◽  
Virtual Reference ◽  
Time Difference Of Arrival ◽  
Positioning Accuracy ◽  
Positioning Systems ◽  
Location System ◽  
Measured Time

The low-orbit dual-satellite passive location system provides a cost-efficient and easy implementation platform, by which positions of unknown emitters on the Earth can be determined through measuring both the time and the frequency differences by two low-orbit satellites in space. However, in reality, this dual-satellite location system has low positioning accuracy because of the existence of systematic errors. In this paper, in order to address the problem of low positioning accuracy in low-orbit dual-satellite systems, a virtualization approach, consisting of the establishment of the virtual reference station and virtual frequency conversion, is proposed to correct systematic errors in the system. Specifically, we first analyze the coming source of systematic errors in the dual-satellite location system, and then, a virtual reference station and virtual frequency are constructed to correct errors in the measured time difference of arrival and the frequency difference of arrival, respectively. Simulation results show that systematic errors caused by the measured time difference of arrival can be significantly reduced, and the correction efficiency, defined as a ratio between remaining errors after implementing the proposed method over uncorrected ones, for the measured frequency difference of arrival, largely relies on both the virtual frequency and the transmission frequency of reference stations.

scholarly journals Assessment of the Steering Precision of a Hydrographic USV along Sounding Profiles Using a High-Precision GNSS RTK Receiver Supported Autopilot

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5637
Author(s):  
Łukasz Marchel ◽  
Cezary Specht ◽  
Mariusz Specht
Keyword(s):  
High Precision ◽  
Low Cost ◽  
Path Following ◽  
Satellite System ◽  
Magnetic Compass ◽  
Reference Station ◽  
Positioning System ◽  
Positioning Accuracy ◽  
Unmanned Surface Vehicles ◽  
Global Navigation Satellite

Unmanned Surface Vehicles (USV) are increasingly used to perform numerous tasks connected with measurements in inland waters and seas. One of such target applications is hydrography, where traditional (manned) bathymetric measurements are increasingly often realized by unmanned surface vehicles. This pertains especially to restricted or hardly navigable waters, in which execution of hydrographic surveys with the use of USVs requires precise maneuvering. Bathymetric measurements should be realized in a way that makes it possible to determine the waterbody’s depth as precisely as possible, and this requires high-precision in navigating along planned sounding profiles. This paper presents research that aimed to determine the accuracy of unmanned surface vehicle steering in autonomous mode (with a Proportional-Integral-Derivative (PID) controller) along planned hydrographic profiles. During the measurements, a high-precision Global Navigation Satellite System (GNSS) Real Time Kinematic (RTK) positioning system based on a GNSS reference station network (positioning accuracy: 1–2 cm, p = 0.95) and a magnetic compass with the stability of course maintenance of 1°–3° Root Mean Square (RMS) were used. For the purpose of evaluating the accuracy of the vessel’s path following along sounding profiles, the cross track error (XTE) measure, i.e., the distance between an USV’s position and the hydrographic profile, calculated transversely to the course, was proposed. The tests were compared with earlier measurements taken by other unmanned surface vehicles, which followed the exact same profiles with the use of much simpler and low-cost multi-GNSS receiver (positioning accuracy: 2–2.5 m or better, p = 0.50), supported with a Fluxgate magnetic compass with a high course measurement accuracy of 0.3° (p = 0.50 at 30 m/s). The research has shown that despite the considerable difference in the positioning accuracy of both devices and incomparably different costs of both solutions, the authors proved that the use of the GNSS RTK positioning system, as opposed to a multi-GNSS system supported with a Fluxgate magnetic compass, influences the precision of USV following sounding profiles to an insignificant extent.

Testing a Medium-Range DGPS Network for the Taiwan Area

1999 ◽  
Vol 52 (2) ◽  
pp. 279-288 ◽  
Author(s):  
C. C. Chang ◽  
S. H. Lin
Keyword(s):  
Sufficient Accuracy ◽  
Reference Station ◽  
Test Results ◽  
Positioning Accuracy ◽  
Atmospheric Delay ◽  
Medium Range ◽  
Differential Corrections ◽  
Highly Correlated ◽  
Operational Range ◽  
Taiwan Area

The DGPS technique can be used for navigation over baselines up to approximately 100 km. However, DGPS positioning accuracy is highly correlated and degraded with the extension of its operational range. It is, hence, improper simply to carry on using conventional DGPS for navigation over longer ranges. An approach aimed at providing sufficient accuracy with the use of a minimum network of reference stations, and the modelling of GPS errors, has been proposed and tested for regional navigation over the Taiwan area. It has been shown from the test results that medium-range DGPS based on using multi-reference stations is capable of improving the RMS coordinate differences by 35%, when compared to the use of a single reference station. The RMS values can be further improved by 14% and 6% in plan coordinates and height respectively, when the modelling of atmospheric delay is applied to the differential corrections based on the pseudorange observables collected from the multi-reference stations.

scholarly journals Urban area GPS positioning accuracy using ASG-EUPOS POZGEO service as a function of session duration

2014 ◽  
Vol 49 (1) ◽  
pp. 33-42 ◽  
Author(s):  
Karol Dawidowicz ◽  
Grzegorz Krzan ◽  
Krzysztof Świątek
Keyword(s):  
Geodetic Network ◽  
Reference Station ◽  
Gps Data ◽  
Dual Frequency ◽  
Post Processing ◽  
Positioning Accuracy ◽  
Gps Positioning ◽  
Session Duration ◽  
Lower Accuracy ◽  
Gnss Observations

ABSTRACT GNSS observations carried out in a network of Continuously Operating Reference Station (CORS) are a complex systems which offer post-processing as well as corrections sent in realtime. In Poland, such a system has been in operation since June 2008, known as the Polish Active Geodetic Network (ASG-EUPOS). Usually the measurements performed in real time characterized lower accuracy than static measurements. For users who demand the highest precision results the post-processing services are provided. The paper presents an analysis of the position determination accuracy using ASG-EUPOS POZGEO service. It is well known that the final accuracy is e.g. the measuring conditions, time of observations or number of measured frequencies dependent. We processed 4 consecutive days of GPS data to determine how the accuracy of derived positional coordinates depends on the length of the observing session, the characteristics of horizon visibility on points and the used in post-processing observations (L1 or L1+L2). The POZGEO results show that horizontal accuracies of about 1-2 cm and vertical accuracies of 4 cm are achievable provided 0.5 hours dual frequency GPS data. The accuracy clearly decreases for point measured under conditions of strongly limited satellite availability

scholarly journals Improving precise point positioning performance based on Prophet model

PLoS ONE ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. e0245561
Author(s):  
Shujian Liao ◽  
Chenbo Yang ◽  
Dengao Li
Keyword(s):  
Real Time ◽  
Reference Station ◽  
Difference Sequence ◽  
Key Factors ◽  
International Gnss Service ◽  
Positioning Accuracy ◽  
Maritime Navigation ◽  
Single Difference ◽  
Point Positioning ◽  
Satellite Clock Bias

Precision point positioning (PPP) is widely used in maritime navigation and other scenarios because it does not require a reference station. In PPP, the satellite clock bias (SCB) cannot be eliminated by differential, thus leading to an increase in positioning error. The prediction accuracy of SCB has become one of the key factors restricting positioning accuracy. Although International GNSS Service (IGS) provides the ultra-rapid ephemeris prediction part (IGU-P), its quality and real-time performance can not meet the practical application. In order to improve the accuracy of PPP, this paper proposes to use the Prophet model to predict SCB. Specifically, SCB sequence is read from the observation part in the ultra-rapid ephemeris (IGU-O) released by IGS. Next, the SCB sequence between adjacent epochs are subtracted to obtain the corresponding SCB single difference sequence. Then using the Prophet model to predict SCB single difference sequence. Finally, the prediction result is substituted into the PPP positioning observation equation to obtain the positioning result. This paper uses the final ephemeris (IGF) published by IGS as a benchmark and compares the experimental results with IGU-P. For the selected four satellites, compared with the results of the IGU-P, the accuracy of SCB prediction of the model in this paper is improved by about 50.3%, 61.7%, 60.4%, and 48.8%. In terms of PPP positioning results, we use Real-time kinematic (RTK) measurements as a benchmark in this paper. Positioning accuracy has increased by 26%, 35%, and 19% in the N, E, and U directions, respectively. The results show that the Prophet model can improve the performance of PPP.

scholarly journals GPS + BDS Network Real-Time Differential Positioning Using a Position Domain Estimation Method

2019 ◽  
Vol 11 (12) ◽  
pp. 1480 ◽  
Author(s):  
Cui ◽  
Yan ◽  
Deng ◽  
Tang ◽  
Zou ◽  
...  
Keyword(s):  
Real Time ◽  
Estimation Method ◽  
Satellite System ◽  
Navigation Satellite ◽  
Improved Method ◽  
Positioning Accuracy ◽  
System Combination ◽  
Time Differential ◽  
Differential Positioning ◽  
User Station

The network real-time differential positioning technique is a good choice for meter and sub-meter level’s navigation. More attention has been paid to the Global Positioning System (GPS) and GPS + GLONASS (GLObal NAvigation Satellite System) network real-time differential positioning, but less on the GPS + BDS (BeiDou Navigation Satellite System) combination. This paper focuses on the GPS + BDS network real-time differential positioning. Since the noise of pseudorange observation is large, carrier-phase-smoothed pseudorange is usually used in the network real-time differential positioning to improve the positioning accuracy, while it will be interrupted once the satellite signal is lost or a cycle slip occurs. An improved algorithm in the position domain based on position variation information is proposed. The improved method is immune to the smoothing window and only depends on the number of available satellites. The performance of the network real-time differential positioning using the improved method is evaluated. The performance of GPS + BDS combination is compared with GPS-only solution as well. The results show that the positioning accuracy can be increased by around 10%–40% using the improved method compared with the traditional one. The improved method is less affected by the satellite constellation. The positioning accuracy of GPS + BDS solution is better than that of GPS-only solution, and can reach up to 0.217 m, 0.159 m and 0.330 m in the north, east and up components for the static user station, and 0.122 m, 0.133 m and 0.432 m for the dynamic user station. The positioning accuracy variation does not only depend on whether the user is inside or outside the network, but also on the position relation between the user and network.

scholarly journals Network Code DGNSS Positioning for Faster L1–L5 GPS Ambiguity Initialization

Sensors ◽  
2020 ◽  
Vol 20 (19) ◽  
pp. 5671 ◽  
Author(s):  
Mieczysław Bakuła ◽  
Marcin Uradziński ◽  
Kamil Krasuski
Keyword(s):  
Network Code ◽  
Reference Station ◽  
Fast Method ◽  
Positioning Accuracy ◽  
Individual Measurement ◽  
Positioning Systems ◽  
True Value ◽  
Gnss Measurements ◽  
Mobile Receiver ◽  
The Impact

This paper presents DGNSS network code positioning using permanent geodetic networks, commonly used in GNSS measurements. Using several reference stations at the same time allows for the independent control of GNSS positioning and facilitates the more realistic estimation of accuracy. Test calculations were made on the basis of real GPS data, using one TRIMBLE mobile receiver and four nearest reference stations of the ASG-EUPOS geodetic system. In addition, DGNSS positioning computational simulations were performed for a case where one mobile GNSS receiver would be able to be used with two (e.g., GPS + Galileo or GPS + GLONASS) or four different positioning systems and different GNSS reference station systems at the same time. To reduce the deviations of the DGPS positioning from a true value, the Kalman filtering for horizontal coordinates and vertical ones was used. The result shows a significant improvement in DGPS positioning accuracy. Based on the numerical analysis carried out, it can be seen that when four GNSS systems are used, it is possible to achieve a DGNSS accuracy of 0.1 m and 0.2 m for horizontal and height coordinates, respectively, using only code measurements. Additionally, the paper presents the impact of the DGNSS code positioning accuracy on the effectiveness of determining ambiguities of phase observations on individual measurement epochs, using the L1–L5 observations of the GPS system and the precise and fast method of ambiguity resolution (PREFMAR). The developed DGNSS positioning methodology can be applied for reliable GNSS navigation using at least two independent GNSS systems.

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