Multi-GNSS Single-Difference Baseline Processing at NGS with newly developed M-PAGES software

2021 ◽  
Author(s):  
Bryan Stressler ◽  
Andria Bilich ◽  
Clement Ogaja ◽  
Jacob Heck
Keyword(s):  
Geodetic Survey ◽  
Integer Ambiguity ◽  
National Geodetic Survey ◽  
Processing Strategy ◽  
Dual Frequency ◽  
Software Suite ◽  
Legacy Software ◽  
Double Differences ◽  
Single Difference ◽  
Gps Observations

<p>The U.S. National Geodetic Survey (NGS) has historically processed dual-frequency GPS observations in a double-differenced mode using the legacy software called the Program for the Adjustment of GPS Ephemerides (PAGES). As part of NGS’ modernization efforts, a new software suite named M-PAGES (i.e., Multi-GNSS PAGES) is being developed to replace PAGES. M-PAGES consists of a suite of C++ and Python libraries, programs, and scripts built to process observations from all GNSS constellations. The M-PAGES team has developed a single-difference baseline processing strategy that is suitable for multi-GNSS. This approach avoids the difficulty of forming double-differences across systems or frequencies, which may inhibit integer ambiguity resolution. The M-PAGES suite is expected to deploy to NGS’ Online Positioning User Service (OPUS) later this year. Here, we present the processing strategy being implemented along with a performance evaluation from sample baseline solutions obtained from data collected within the NOAA CORS Network.</p>

Preliminary Positioning Results From NGS’s Upcoming Multi-GNSS Processing Software

2020 ◽  
Author(s):  
Bryan Stressler ◽  
Jacob Heck ◽  
Andria Bilich ◽  
Clement Ogaja
Keyword(s):  
Data Processing ◽  
Satellite System ◽  
Geodetic Survey ◽  
Double Difference ◽  
National Geodetic Survey ◽  
Dual Frequency ◽  
International Gnss Service ◽  
Processing Software ◽  
Global Navigation Satellite ◽  
Gnss Processing

<p>The U.S. National Geodetic Survey (NGS) is undertaking a project to replace and modernize its global navigation satellite system (GNSS) processing software that has been in use for several decades. The goals of this project are to: 1) transition from dual-frequency GPS-only to multi-constellation multi-frequency data processing, 2) develop well-documented modular and extensible software written in modern programming and scripting languages, and 3) replace the operational PAGES software suite as the processing engine responsible for monitoring the NOAA Continuously Operating Reference System Network (NCN), orbit production for the International GNSS Service (IGS) combinations, and the Online Positioning User Service (OPUS). To date, the GNSS software team at NGS has developed the foundational software libraries and tools needed for GNSS data processing (e.g, RINEX readers, standard GNSS models) and has begun to produce double-difference baseline solutions with the new software. This valuable first step enables us to compare solutions from the new software with those of the legacy PAGES software. Here we present our preliminary solutions, compare them with those of PAGES, and discuss the next steps to improve the positioning accuracy and to take full advantage of multi-GNSS observations.</p>

scholarly journals Rapid static GNSS data processing using online services

2014 ◽  
Vol 4 (1) ◽  
Author(s):  
M. Berber ◽  
A. Ustun ◽  
M. Yetkin
Keyword(s):  
Data Processing ◽  
Satellite System ◽  
Geodetic Survey ◽  
National Geodetic Survey ◽  
Dual Frequency ◽  
Online Data ◽  
Vertical Coordinate ◽  
Static Data ◽  
Global Navigation Satellite ◽  
Gnss Data

AbstractRecently, many organizations have begun providing online GNSS (Global Navigation Satellite System) data processing services. Currently, only one of these organizations i.e., OPUS (On-line Positioning Users Service) provides a rapid static data processing option. In case of static online data processing, the users are required to submit at least two hours of data to get reasonably precise results. To provide processing option with less than two hours of data, NGS (National Geodetic Survey) developed OPUS–RS for rapid static data processing so that usersmay submit as little as 15 minutes of dual frequency GNSS data. In this study, multiple observation sessions are conducted at the same locations to compare OPUS-RS generated coordinates among the different sessions to see whether separate values agree with each other. The results indicate that with OPUS-RS results the differences in horizontal coordinates agree with each other within 3.5 cm and vertical coordinates agree within 7.2 cm. For an independent check, OPUS-RS results are also compared against LGO(Leica Geo Office) produced Static results; this comparison yielded up to 4.5 cm variations among horizontal coordinate differences and variations among vertical coordinate differences are up to 11.4 cm.

scholarly journals High-Accuracy Real-Time Kinematic Positioning with Multiple Rover Receivers Sharing Common Clock

2021 ◽  
Vol 13 (4) ◽  
pp. 823
Author(s):  
Lin Zhao ◽  
Jiachang Jiang ◽  
Liang Li ◽  
Chun Jia ◽  
Jianhua Cheng
Keyword(s):  
Real Time ◽  
Ambiguity Resolution ◽  
Temporal Stability ◽  
Estimation Method ◽  
Satellite System ◽  
Integer Ambiguity ◽  
Dual Frequency ◽  
Kinematic Positioning ◽  
Real Time Kinematic ◽  
Satellite Visibility

Since the traditional real-time kinematic positioning method is limited by the reduced satellite visibility from the deprived navigational environments, we, therefore, propose an improved RTK method with multiple rover receivers sharing a common clock. The proposed method can enhance observational redundancy by blending the observations from each rover receiver together so that the model strength will be improved. Integer ambiguity resolution of the proposed method is challenged in the presence of several inter-receiver biases (IRB). The IRB including inter-receiver code bias (IRCB) and inter-receiver phase bias (IRPB) is calibrated by the pre-estimation method because of their temporal stability. Multiple BeiDou Navigation Satellite System (BDS) dual-frequency datasets are collected to test the proposed method. The experimental results have shown that the IRCB and IRPB under the common clock mode are sufficiently stable for the ambiguity resolution. Compared with the traditional method, the ambiguity resolution success rate and positioning accuracy of the proposed method can be improved by 19.5% and 46.4% in the restricted satellite visibility environments.

scholarly journals Estimation and evaluation of COSMIC radio occultation excess phase using undifferenced measurements

2017 ◽  
Vol 10 (5) ◽  
pp. 1813-1821
Author(s):  
Pengfei Xia ◽  
Shirong Ye ◽  
Kecai Jiang ◽  
Dezhong Chen
Keyword(s):  
Radio Occultation ◽  
Weather Prediction ◽  
Lower Troposphere ◽  
Double Difference ◽  
Cosmic Radio ◽  
Processing Strategy ◽  
Single Difference ◽  
Excess Phase ◽  
Mean Square Errors ◽  
Better Than

Abstract. In the GPS radio occultation technique, the atmospheric excess phase (AEP) can be used to derive the refractivity, which is an important quantity in numerical weather prediction. The AEP is conventionally estimated based on GPS double-difference or single-difference techniques. These two techniques, however, rely on the reference data in the data processing, increasing the complexity of computation. In this study, an undifferenced (ND) processing strategy is proposed to estimate the AEP. To begin with, we use PANDA (Positioning and Navigation Data Analyst) software to perform the precise orbit determination (POD) for the purpose of acquiring the position and velocity of the mass centre of the COSMIC (The Constellation Observing System for Meteorology, Ionosphere and Climate) satellites and the corresponding receiver clock offset. The bending angles, refractivity and dry temperature profiles are derived from the estimated AEP using Radio Occultation Processing Package (ROPP) software. The ND method is validated by the COSMIC products in typical rising and setting occultation events. Results indicate that rms (root mean square) errors of relative refractivity differences between undifferenced and atmospheric profiles (atmPrf) provided by UCAR/CDAAC (University Corporation for Atmospheric Research/COSMIC Data Analysis and Archive Centre) are better than 4 and 3 % in rising and setting occultation events respectively. In addition, we also compare the relative refractivity bias between ND-derived methods and atmPrf profiles of globally distributed 200 COSMIC occultation events on 12 December 2013. The statistical results indicate that the average rms relative refractivity deviation between ND-derived and COSMIC profiles is better than 2 % in the rising occultation event and better than 1.7 % in the setting occultation event. Moreover, the observed COSMIC refractivity profiles from ND processing strategy are further validated using European Centre for Medium-Range Weather Forecasts (ECMWF) analysis data, and the results indicate that the undifferenced method reduces the noise level on the excess phase paths in the lower troposphere compared to the single-difference processing strategy.

A Method for the Evaluation of Vertical Crustal Movement from Scattered Geodetic Relevellings

1974 ◽  
Vol 11 (5) ◽  
pp. 605-610 ◽  
Author(s):  
P. Vaníček ◽  
D. Christodulidis
Keyword(s):  
Chesapeake Bay ◽  
Statistical Significance ◽  
Geodetic Survey ◽  
National Geodetic Survey ◽  
Specific Level ◽  
Vertical Crustal Movement ◽  
Crustal Movements ◽  
Velocity Surface ◽  
Vertical Crustal Movements ◽  
The U.S

The existing techniques for the quantitative evaluation of vertical crustal movements from geodetic spirit levelling have one common feature. They can deal only with a complete network of systematically relevelled connected lines. This paper presents a method, based on the least-squares fitting of a velocity surface, capable of using scattered as well as connected relevelled segments. A facility to choose a specific level of statistical significance of the results is built in. The performance of the method is tested on data for the vicinity of Chesapeake Bay. The results compare well with those of the U.S. National Geodetic Survey.

Research on the method of dual-frequency microwave diagnosis of plasma for solving phase integer ambiguity

2021 ◽  
Author(s):  
Xiaoping Li ◽  
Chengwei Zhao ◽  
Yanming Liu ◽  
Jiahui Zhang ◽  
Donglin Liu ◽  
...  
Keyword(s):  
Integer Ambiguity ◽  
Dual Frequency

The experimental geoid 2020 – the first joint geoid model for the North American and Pacific Geopotential Datum 

2021 ◽  
Author(s):  
Yan Ming Wang ◽  
Xiaopeng Li ◽  
Kevin Ahlgren ◽  
Jordan Krcmaric ◽  
Ryan Hardy ◽  
...  
Keyword(s):  
North American ◽  
Gravity Data ◽  
The United States ◽  
Geodetic Survey ◽  
Airborne Gravity ◽  
Data Sets ◽  
National Geodetic Survey ◽  
Geoid Model ◽  
Satellite Gravity ◽  
The North

<p>For the upcoming North American-Pacific Geopotential Datum of 2022, the National Geodetic Survey (NGS), the Canadian Geodetic Survey (CGS) and the National Institute of Statistics and Geography of Mexico (INEGI) computed the first joint experimental gravimetric geoid model (xGEOID) on 1’x1’ grids that covers a region bordered by latitude 0 to 85 degree, longitude 180 to 350 degree east. xGEOID20 models are computed using terrestrial gravity data, the latest satellite gravity model GOCO06S, altimetric gravity data DTU15, and an additional nine airborne gravity blocks of the GRAV-D project, for a total of 63 blocks. In addition, a digital elevation model in a 3” grid was produced by combining MERIT, TanDEM-X, and USGS-NED and used for the topographic/gravimetric reductions. The geoid models computed from the height anomalies (NGS) and from the Helmert-Stokes scheme (CGS) were combined using two different weighting schemes, then evaluated against the independent GPS/leveling data sets. The models perform in a very similar way, and the geoid comparisons with the most accurate Geoid Slope Validation Surveys (GSVS) from 2011, 2014 and 2017 indicate that the relative geoid accuracy could be around 1-2 cm baseline lengths up to 300 km for these GSVS lines in the United States. The xGEOID20 A/B models were selected from the combined models based on the validation results. The geoid accuracies were also estimated using the forward modeling.</p>

scholarly journals VLBI Measurements of Radio Source Positions at Three U.S. Stations

1981 ◽  
Vol 63 ◽  
pp. 329-336
Author(s):  
Shu-Hua Ye
Keyword(s):  
Radio Source ◽  
Radio Astronomy ◽  
Data Reduction ◽  
Geodetic Survey ◽  
Time Span ◽  
National Geodetic Survey ◽  
Owens Valley ◽  
Radio Observatory ◽  
The U.S

AbstractResults of VLBI measurement of 14 radio source positions at three U.S. stations during the MERIT short campaign is presented. Comparisons with other solutions are given, together with the comparisons between several radio source catalogues.During the MERIT short campaign, several observatories cooperated in VLBI measurements organized jointly by the U.S. National Geodetic Survey (NGS) and the National Aeronautics and Space Administration (NASA). There were two 7-day observations arranged from Sept. 26 to Oct. 2 and from Oct. 16 to Oct. 22, with time span nearly 23 hours per day. Details of the observation and data reduction have been published elsewhere (1). This paper deals with radio source positions determined by three U.S. stations, the Haystack Observatory, the Harvard Radio Astronomy Station (HRAS) and the Owens Valley Radio Observatory (OVRO).

scholarly journals Some Considerations in the Use of Very-Long-Baseline-Interferometry to Establish Reference Coordinate Systems for Geodynamics

1980 ◽  
Vol 56 ◽  
pp. 205-216
Author(s):  
Douglas S. Robertson
Keyword(s):  
Reference Frames ◽  
Geodetic Survey ◽  
Limiting Factors ◽  
Radio Sources ◽  
National Geodetic Survey ◽  
Terrestrial Reference Frames ◽  
Long Baseline ◽  
Lithospheric Plates ◽  
Long Time ◽  
The Stability

AbstractPresent knowledge of the number, distribution, proper motion and structures of extragalactic radio sources indicates that there should be no problem in defining a celestial reference frame with stabilities of a few milliseconds of arc over time spans of the order of a decade. One of the limiting factors appears to be the structure of the sources. By measuring and monitoring these structures, the stability could probably be improved by as much as one or two orders of magnitude. Even without this improvement, a network of properly distributed fixed observatories making regular interferometric observations of these radio sources could be used to define a terrestrial coordinate system that could be maintained at the few centimeter level over indefinitely long time periods. Such a stable terrestrial reference system would be useful for a host of modern geodetic and geodynamic applications, including, in particular, studies of the time varying deformations and relative motions of lithospheric plates. The National Geodetic Survey has already begun work on a three station base network of permanent observatories under project POLARIS as a first step toward implementing the new celestial and terrestrial reference frames. It is hoped that others will join in the effort and make the new reference frames a reality by the middle of this decade.

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