Increase of the Earth’s orientation parameters combination accuracy in Main Metrological Center of State Service for time, frequency and Earth’s orientation parameters evaluation

General Increase ◽

State Service ◽

Satellite Systems ◽

Time Frequency ◽

Long Baseline ◽

Increase In Accuracy ◽

Orientation Parameters ◽

Metrological Center

The results of improvement of programs and methods of Earth’s orientation parameters (EOP) combination of vary long baseline interferometry (VLBI), global navigation satellite systems (GNSS) and satillite laser ranging (SLR) in Main Metrological Center of State Service for Time, Frequency and Earth’s orientation parameters evaluation are considered. Nowdays, the combination of different geodetic thecnics measurements in Main Metrological Center of State Service for time, frequency and Earth’s orientation parameters evaluation is provided both at the time raws level, and on the observations level. The increasing accuracy of Universal time UT1 was caused by using in combination observational data from new thirteen-meter antennas of the two-element very long base interferometer which was created in Institute of Applayed Astronomy of Russian Academy of Science. In general, increase in accuracy of combination values of the Earth’s orientation parameters was caused both by the increase in accuracy of the separate time raws, and by the improving of the combination algorithms.

Improving methods and facilities of Earth’s orientation parameters evaluation in Main metrological center of State service for time, frequency and Earth’s orientation parameters evaluation

Izmeritel`naya Tekhnika ◽

10.32446/0368-1025it.2020-5-16-21 ◽

2020 ◽

pp. 16-21

Author(s):

Sergey L. Pasynok ◽

Igor V. Bezmenov ◽

Igor Yu. Ignatenko ◽

Efim N. Tcyba ◽

Vladimir E. Zharov

Keyword(s):

Satellite Laser Ranging ◽

Laser Ranging ◽

Lunar Laser Ranging ◽

State Service ◽

Radio Engineering ◽

Time Frequency ◽

Orientation Parameters ◽

Metrological Center ◽

Technical Physics

The results of improvement of methods and facilities of Earth’s orientation parameters in Main metrological center of State service for time, frequency and Earth’s orientation parameters evaluatio in the last five years are considered. The hardware and software are modernized. As result Main metrological center of State service for time, frequency and Earth’s orientation parameters evaluation has program correlator now, the calculation thechnic was improved, Analysis Center of Main metrological center of State service for time, frequency and Earth’s orientation parameters evaluation was created. The Russian metrological institute of technical physics and radio engineering has satellite laser ranging station of new generation now. This station was created by Institute for precision instrument engineering. The new software for satellite laser ranging processing and lunar laser ranging processing was created. The new sofware of the global navigation satellite systems processing was developed. The software for very long base interferometry data processing and software for combination were modernized. Development of evaluation and predictioning facilities of Earth’s orientation parameters Russian metrological institute of technical physics and radio engineering was provided according to modern international direction. This allowed to provide work of evaluation and predictioning of Earth’s orientation parameters at the high international level.

GNSS RTK Positioning Augmented with Large LEO Constellation

Remote Sensing ◽

10.3390/rs11030228 ◽

2019 ◽

Vol 11 (3) ◽

pp. 228 ◽

Cited By ~ 6

Author(s):

Xingxing Li ◽

Hongbo Lv ◽

Fujian Ma ◽

Xin Li ◽

Jinghui Liu ◽

...

Keyword(s):

Low Earth Orbit ◽

Convergence Time ◽

Current Status ◽

Initial Assessment ◽

Satellite Systems ◽

Long Baseline ◽

Leo Satellites ◽

Long Baselines

It is widely known that in real-time kinematic (RTK) solution, the convergence and ambiguity-fixed speeds are critical requirements to achieve centimeter-level positioning, especially in medium-to-long baselines. Recently, the current status of the global navigation satellite systems (GNSS) can be improved by employing low earth orbit (LEO) satellites. In this study, an initial assessment is applied for LEO constellations augmented GNSS RTK positioning, where four designed LEO constellations with different satellite numbers, as well as the nominal GPS constellation, are simulated and adopted for analysis. In terms of aforementioned constellations solutions, the statistical results of a 68.7-km baseline show that when introducing 60, 96, 192, and 288 polar-orbiting LEO constellations, the RTK convergence time can be shortened from 4.94 to 2.73, 1.47, 0.92, and 0.73 min, respectively. In addition, the average time to first fix (TTFF) can be decreased from 7.28 to 3.33, 2.38, 1.22, and 0.87 min, respectively. Meanwhile, further improvements could be satisfied in several elements such as corresponding fixing ratio, number of visible satellites, position dilution of precision (PDOP) and baseline solution precision. Furthermore, the performance of the combined GPS/LEO RTK is evaluated over various-length baselines, based on convergence time and TTFF. The research findings show that the medium-to-long baseline schemes confirm that LEO satellites do helpfully obtain faster convergence and fixing, especially in the case of long baselines, using large LEO constellations, subsequently, the average TTFF for long baselines has a substantial shortened about 90%, in other words from 12 to 2 min approximately by combining with the larger LEO constellation of 192 or 288 satellites. It is interesting to denote that similar improvements can be observed from the convergence time.

Volume 2: Integrated System Design and Implementation; Structural Health Monitoring; Bioinspired Smart Materials and Systems; Energy Harvesting ◽

The Contribution of LARES to Global Climate Change Studies With Geodetic Satellites

10.1115/smasis2015-8924 ◽

2015 ◽

Cited By ~ 3

Author(s):

Giampiero Sindoni ◽

Claudio Paris ◽

Cristian Vendittozzi ◽

Erricos C. Pavlis ◽

Ignazio Ciufolini ◽

...

Keyword(s):

Reference Frame ◽

Earth Science ◽

Global Climate ◽

Temporal Variations ◽

Terrestrial Reference Frame ◽

Satellite Systems ◽

Long Baseline ◽

Geophysical Processes ◽

Satellite Laser Ranging (SLR) makes an important contribution to Earth science providing the most accurate measurement of the long-wavelength components of Earth’s gravity field, including their temporal variations. Furthermore, SLR data along with those from the other three geometric space techniques, Very Long Baseline Interferometry (VLBI), Global Navigation Satellite Systems (GNSS) and DORIS, generate and maintain the International Terrestrial Reference Frame (ITRF) that is used as a reference by all Earth Observing systems and beyond. As a result we obtain accurate station positions and linear velocities, a manifestation of tectonic plate movements important in earthquake studies and in geophysics in general. The “geodetic” satellites used in SLR are passive spheres characterized by very high density, with little else than gravity perturbing their orbits. As a result they define a very stable reference frame, defining primarily and uniquely the origin of the ITRF, and in equal shares, its scale. The ITRF is indeed used as “the” standard to which we can compare regional, GNSS-derived and alternate frames. The melting of global icecaps, ocean and atmospheric circulation, sea-level change, hydrological and internal Earth-mass redistribution are nowadays monitored using satellites. The observations and products of these missions are geolocated and referenced using the ITRF. This allows scientists to splice together records from various missions sometimes several years apart, to generate useful records for monitoring geophysical processes over several decades. The exchange of angular momentum between the atmosphere and solid Earth for example is measured and can be exploited for monitoring global change. LARES, an Italian Space Agency (ASI) satellite, is the latest geodetic satellite placed in orbit. Its main contribution is in the area of geodesy and the definition of the ITRF in particular and this presentation will discuss the improvements it will make in the aforementioned areas.

Determination of UT1 by VLBI

Proceedings of the International Astronomical Union ◽

10.1017/s1743921310008859 ◽

2009 ◽

Vol 5 (H15) ◽

pp. 216-216

Author(s):

Harald Schuh ◽

Johannes Boehm ◽

Sigrid Englich ◽

Axel Nothnagel

Keyword(s):

Satellite Orbit ◽

Length Of Day ◽

Satellite Systems ◽

Long Baseline ◽

Geodetic Technique ◽

Set Up ◽

Space Geodetic Technique

AbstractVery Long Baseline Interferometry (VLBI) is the only space geodetic technique which is capable of estimating the Earth's phase of rotation, expressed as Universal Time UT1, over time scales of a few days or longer. Satellite-observing techniques like the Global Navigation Satellite Systems (GNSS) are suffering from the fact that Earth rotation is indistinguishable from a rotation of the satellite orbit nodes, which requires the imposition of special procedures to extract UT1 or length of day information. Whereas 24 hour VLBI network sessions are carried out at about three days per week, the hour-long one-baseline intensive sessions (‘Intensives’) are observed from Monday to Friday (INT1) on the baseline Wettzell (Germany) to Kokee Park (Hawaii, U.S.A.), and from Saturday to Sunday on the baseline Tsukuba (Japan) to Wettzell (INT2). Additionally, INT3 sessions are carried out on Mondays between Wettzell, Tsukuba, and Ny-Alesund (Norway), and ultra-rapid e-Intensives between E! urope and Japan also include the baseline Metsähovi (Finland) to Kashima (Japan). The Intensives have been set up to determine daily estimates of UT1 and to be used for UT1 predictions. Because of the short duration and the limited number of stations the observations can nowadays be e-transferred to the correlators, or to a node close to the correlator, and the estimates of UT1 are available shortly after the last observation thus allowing the results to be used for prediction purposes.

Low cost GNSS receivers in time synchronization systems

Bulletin of the Military University of Technology ◽

10.5604/01.3001.0011.8035 ◽

2018 ◽

Vol 67 (1) ◽

pp. 65-72

Author(s):

Grzegorz Czopik ◽

Tomasz Kraszewski

Keyword(s):

Time Synchronization ◽

Low Cost ◽

Satellite Systems ◽

Time Frequency ◽

Delay Times ◽

Gnss Receivers ◽

Frequency Counter ◽

The One ◽

The GNSS (GNSS — Global Navigation Satellite Systems) receivers can be utilized to obtain accurate time markers. The preliminary results of the cheap GNSS receivers’ tests are presented in the paper. The one receiver’s price (including antenna) does not exceed 30 $. The studies on the use of receivers in the time synchronization systems were executed. Three identical models of receiver modules were used. The 1PPS (1PPS — 1 Pulse Per Second) signals available on the receiver’s output were used. The 1PPS’s main time characteristics were described. Delay times between different receivers 1PPS signals were measured. Measurements were taken using 1 GHz oscilloscope and precise time/frequency counter T3200U. Keywords: time synchronization, 1PPS, GNSS, GPS time

Earth Orientation Parameter Estimation by Integrating VLBI and GNSS on the Observation Level

10.5194/egusphere-egu21-616 ◽

2021 ◽

Author(s):

Jungang Wang ◽

Kyriakos Balidakis ◽

Maorong Ge ◽

Robert Heinkelmann ◽

Harald Schuh

Keyword(s):

Polar Motion ◽

Reference Frames ◽

Satellite Systems ◽

Earth Orientation ◽

Long Baseline ◽

Space Geodetic Techniques ◽

The Impact ◽

Globally Distributed

The terrestrial and celestial reference frames are linked by the Earth Orientation Parameters (EOP), which describe the irregularities of the Earth's rotation and are determined by the space geodetic techniques, namely, Very Long Baseline Interferometry (VLBI), Satellite Laser Ranging (SLR), Global Navigation Satellite Systems (GNSS), and Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS). The satellite geodetic techniques (SLR, GNSS, and DORIS) cannot determine the UT1-UTC or celestial pole offsets (CPO), rendering VLBI the only technique capable of determining full EOP set. On the other hand, the GNSS technique provides precise polar motion estimates due to the continuous observations from a globally distributed network. Integrating VLBI and GNSS provides the full set of EOP and guarantees a superior accuracy than any single-technique solution.In this study we focus on the integrated estimation of the full EOP set from GNSS and VLBI. Using five VLBI continuous observing campaigns (CONT05&#8211;CONT17), the GNSS and VLBI observations are processed concurrently in a common least-squares estimator. The impact of applying global ties (EOP), local ties, and tropospheric ties, and combinations thereof is investigated. The polar motion estimates in integrated solution are dominated by the huge GNSS observations, and the accuracy in terms of weighted root mean squares (WRMS) is ~40&#160;&#956;as compared to the IERS 14 C04 product, which is much better than that of the VLBI-only solution. The UT1-UTC and CPO in the integrated solution also show slight improvement compared to the VLBI-only solution. Moreover, the CPO agreement between the two networks in CONT17, i.e., the VLBA and IVS networks, shows an improvement of 20% to 40% in the integrated solution with different types of ties applied.

NEW EOP, TRF and CRF determination by GNSS & VLBI COMBINATION

10.5194/egusphere-egu2020-19169 ◽

2020 ◽

Author(s):

Jean-Yves Richard ◽

Maria Karbon ◽

Chrsitian Bizouard ◽

Sebastien Lambert ◽

Olivier Becker

Keyword(s):

Polar Coordinates ◽

Normal Equation ◽

Satellite Systems ◽

Earth Orientation ◽

Long Baseline ◽

Time Period ◽

Station Coordinates ◽

The Individual ◽

The Earth orientation parameters (EOP), the regular products of IERS Earth Orientation Centre, are computed at daily bases by combination of EOP solutions using different astro-geodetic techniques. At SYRTE we have developed a strategy of combination of the Global Navigation Satellite Systems (GNSS) and Very Long Baseline Interferometry (VLBI) techniques at normal equation level using Dynamo software maintained by CNES (France). This approach allows to produce the EOP at the daily bases, which contains polar coordinates (x,y) and their rates (xr,yr), universal time UT1 and its rate LOD, and corrections from IAU2000A/2006 precession-nutation model (dX,dY), and in the same run station coordinates constituting the terrestrial frame (TRF) and the quasar coordinates constituting the celestial frame (CRF). The recorded EOP solutions obtained from GNSS and VLBI combination at weekly bases is recently maintained by SYRTE.The strategy applied to consistently combine &#160;the IGS and IVS &#160;solutions provided &#160;in Sinex format over the time period 2000-2020 are presented and the resulting &#160;EOP, station positions (TRF) and quasars coordinates (CRF) are analysed and evaluated, differences w.r.t. the individual solutions and the IERS time-series investigated.

Comparing atmospheric data and models at station Wettzell during CONT17

Advances in Geosciences ◽

10.5194/adgeo-50-1-2019 ◽

2019 ◽

Vol 50 ◽

pp. 1-7

Author(s):

Daniel Landskron ◽

Johannes Böhm ◽

Thomas Klügel ◽

Torben Schüler

Keyword(s):

Water Vapor ◽

Mapping Function ◽

Radiosonde Data ◽

Data Set ◽

Mapping Functions ◽

Satellite Systems ◽

Long Baseline ◽

Troposphere Delays

Abstract. During the Continuous Very Long Baseline Interferometry (VLBI) Campaign 2017 (CONT17), carried out from 28 November through 12 December 2017, an extensive data set of atmospheric observations was acquired at the Geodetic Observatory Wettzell. In addition to in situ measurements of temperature, humidity, pressure or wind speed at the surface, radiosonde ascents yielded meteorological parameters continually up to 25 km height, and integrated water vapor (IWV) was obtained at several elevations and azimuths from a water vapor radiometer. Troposphere delays estimated from Global Navigation Satellite Systems (GNSS) observations plus comparative values from two different Numerical Weather Models (NWMs) complete the abundance of data. In this presentation, we compare these data sets to parameters of the Vienna Mapping Functions 1 and 3 (VMF1 & VMF3), which are based on NWM data by the ECMWF, and to estimates of VLBI analysis using the Vienna VLBI and Satellite Software (VieVS). On the one hand, we contrast the variety of troposphere delays in zenith direction with each other, while on the other hand we utilize radiosonde data and meteorological observations at the site to create local mapping functions which can then be compared to VMF3 and VMF1 at Wettzell. In general, we thus received very good accordance between the different solutions. Also in terms of the mapping functions, the local radiosonde mapping function is in consistence with VMF1 and VMF3 with differences less than 5 mm at 5∘ elevation.

Multicomponent Analysis of Ionospheric Scintillation Effects Using the Synchrosqueezing Technique for Monitoring and Mitigating their Impact on GNSS Signals

Journal of Navigation ◽

10.1017/s0373463318000929 ◽

2018 ◽

Vol 72 (3) ◽

pp. 669-684

Author(s):

G. Sivavaraprasad ◽

D. Venkata Ratnam ◽

Yuichi Otsuka

Keyword(s):

Ionospheric Scintillation ◽

Fluctuation Analysis ◽

Radio Communication ◽

Adaptive Wavelet ◽

Satellite Systems ◽

Time Frequency ◽

Low Pass ◽

Software Navigation ◽

Ionospheric scintillation effects degrade satellite-based radio communication/navigation links and influence the performance of Global Navigation Satellite Systems (GNSS). An adaptive wavelet-based decomposition technique, Synchrosqueezing Transform (SST), with a Detrended Fluctuation Analysis (DFA) algorithm has been implemented for time-frequency representation of GNSS multi-component signals and mitigation of scintillation effects. Synthetic In-phase (I) and Quadra-phase (Q) samples were collected from the Cornell Scintillation Model (CSM) and the CSM amplitude scintillation signal was processed with SST-DFA for the detection of noisy scintillation components and mitigation of ionospheric scintillation effects. Also, performance of the SST-DFA algorithm was tested for real-time GNSS ionospheric scintillation data collected from a GNSS Software Navigation Receiver (GSNRx) located at a low-latitude station in Rio de Janeiro, Brazil. The de-noising performance of the SST-DFA algorithm was further evaluated and compared with a low-pass Butterworth filter during different ionospheric scintillation time periods. The experimental results clearly demonstrated that the proposed method is reliable for mitigation of ionospheric scintillation noise both in time and frequency scales.

Earth Orientation Parameters determination by GNSS & VLBI Combination at Normal Equation Level

10.5194/egusphere-egu21-2511 ◽

2021 ◽

Author(s):

Jean-Yves Richard ◽

Christian Bizouard ◽

Sebastien Lambert ◽

Olivier Becker

Keyword(s):

Polar Coordinates ◽

Normal Equation ◽

Earth Orientation Parameters ◽

Satellite Systems ◽

Earth Orientation ◽

Long Baseline ◽

Station Coordinates ◽

The Individual ◽

Orientation Parameters

The Earth orientation parameters (EOP), the regular products of IERS Earth Orientation Centre, are computed at daily bases by combination of EOP solutions using different astro-geodetic techniques. At SYRTE we have developed a strategy of combination of the Global Navigation Satellite Systems (GNSS) and Very Long Baseline Interferometry (VLBI) techniques at normal equation level using Dynamo software maintained by CNES (France). This approach allows to produce the EOP at the daily bases, which contains polar coordinates (x,y) and their rates (xr,yr), universal time UT1 and its rate LOD, and corrections from IAU2000A/2006 precession-nutation model (dX,dY), and in the same run station coordinates constituting the terrestrial frame (TRF). The recorded EOP solutions obtained from GNSS and VLBI combination at weekly bases is recently maintained by SYRTE.The strategy applied to consistently combine the IGS and IVS solutions provided in Sinex format over the time period 2000-2021 are presented and the resulting EOP, station positions (TRF) are analysed and evaluated, differences w.r.t. the individual solutions and the IERS time-series investigated.