PresentationPDF Available

International Earth rotation and Reference Systems Service (IERS): Structure, Data, Products, Applications

  • March 2012
DOI: 10.13140/RG.2.2.26817.40800/1
  • Conference: Internal Student Seminars
  • At: Geomatics Engineering Department
  • Affiliation: University of Isfahan
Authors:
Amir Allahvirdi-Zadeh at Curtin University
Amir Allahvirdi-Zadeh
Download file PDFDownload file PDF
Read file
Download citation

Abstract

I introduced the International Earth Rotation and Reference Systems Service (IERS) at the University of Isfahan: The IERS was established in 1987 by the International Astronomical Union and the International Union of Geodesy and Geophysics. According to the Terms of Reference, the IERS accomplishes its mission through the following components: Technique Centres, Product Centres, Combination Centres, Analysis Coordinator, Central Bureau, Directing Board. The IERS provides data on Earth orientation, on the International Celestial Reference System/Frame, on the International Terrestrial Reference System/Frame, and on geophysical fluids. It maintains also Conventions containing models, constants, and standards.
IERS-AmirAllahvirdi-Zadeh-Referenc
es.pdf
Content uploaded by Amir Allahvirdi-Zadeh
Author content
All content in this area was uploaded by Amir Allahvirdi-Zadeh on Feb 21, 2022
Content may be subject to copyright.
IERS-Amir Allahvirdi-Zad
eh.pdf
Content uploaded by Amir Allahvirdi-Zadeh
Author content
All content in this area was uploaded by Amir Allahvirdi-Zadeh on Nov 26, 2021
Content may be subject to copyright.
A preview of the PDF is not available
... There are a set of presentations about international services related to geodesy including IGS that are available in [1], [2], [3] and [4]. Study [5] for the quality control of the GPS data. ...
Precise Positioning By Smartphone
Presentation
Full-text available
  • May 2019
Precise Positioning by smartphones is in the early steps. In this presentation, an overview of this novel subject is discussed and possible future works are introduced.
View
... The presentations of the other international services are available in [1], [2], and [3]. Study [4] for the quality control of the GPS data. ...
International Doris Service (IDS): Data and Products
Presentation
Full-text available
  • Mar 2012
I introduced the international Doris Service in the internal seminars of the University of Isfahan. The Doris system is a french civil precise orbit determination and positioning system. It is based on the principle of the Doppler effect with a transmitting terrestrial beacons network and onboard instruments on the satellite's payload (antenna, radio receiver, and oscillator ultra-stable). Doris is one of three systems used for the precise determination of the Jason-1 satellite's orbit. Several of these techniques are sometimes merged on the same satellite: Jason-1 satellite includes three tracking systems, Doris, location by GPS, and laser telemetry. The Doris system perfectly corresponds to the specifications required for the ocean's topography observations and the amplitude of the observed phenomena: it is now enabled to measure the satellite position on its orbit close to 1 cm. It is interesting to compare this precision with the precision obtained at the beginning of the space age, where the satellite position was estimated close to 20 km then close to 20 meters in the '80s. Since 1998, the Diode navigator has added real-time measurement processing capability for satellite navigation. The Doris system was designed by CNES, the French space agency, in partnership with France's mapping and survey agency IGN and the space geodesy research institute GRGS. Since 2003, IDS is an international service that provides support, through Doris data and products. The successive missions since Spot 2 and Topex/Poseidon have truly demonstrated its performance.
View
... The presentations of the other international services are available in [1], [2], and [3]. Study [4] for the quality control of the GPS data. ...
A deep look at the International Laser Ranging Service (ILRS)
Presentation
Full-text available
  • Mar 2012
I introduced the International Laser Ranging Service (ILRS), its data and products in the internal student's seminar at the University of Isfahan: Satellite Laser Ranging (SLR) and Lunar Laser Ranging (LLR) use short-pulse lasers and state-of-the-art optical receivers and timing electronics to measure the two-way time of flight (and hence distance) from ground stations to retroreflector arrays on Earth-orbiting satellites and the Moon. Scientific products derived using SLR and LLR data include precise geocentric positions and motions of ground stations, satellite orbits, components of Earth’s gravity field and their temporal variations, Earth Orientation Parameters (EOP), precise lunar ephemerides, and information about the internal structure of the Moon. Laser-ranging systems are already measuring the one-way distance to remote optical receivers in space and can perform very accurate time transfer between sites far apart. Laser-ranging activities are organized under the International Laser Ranging Service (ILRS) which provides global satellite and lunar laser ranging data and their derived data products to support research in geodesy, geophysics, Lunar science, and fundamental constants. This includes data products that are fundamental to the International Terrestrial Reference Frame (ITRF), which is established and maintained by the International Earth Rotation and Reference Systems Service (IERS). The ILRS develops the necessary global standards/specifications for laser ranging activities and encourages international adherence to its conventions.
View
... The presentations of the other international services are available in [1], [2], and [3]. Study [4] for the quality control of the GPS data. ...
International GNSS Service (IGS): Structure, Data, and Products
Presentation
Full-text available
  • Mar 2012
I introduced the International GNSS Service in the internal students' seminar at the University of Isfahan: The International GNSS Service (IGS) has ensured open access, high-quality GNSS data products since 1994. These products enable access to the definitive global reference frame for scientific, educational, and commercial applications – a tremendous benefit to the public, and a key support element for scientific advancements. The IGS at a Glance A voluntary federation of over 200 self-funding agencies, universities, and research institutions in more than 100 countries; working together to provide the highest precision GPS satellite orbits in the world. Providing free and open access to the highest precision products available for scientific advancement and public benefit. These products support a wide variety of applications that touch millions of users in virtually all segments of the global economy Producing products that support the realization of the International Terrestrial Reference Frame while providing access to tracking data from over 400 worldwide reference stations Working for the continuous development of new applications and products through Working Groups and Pilot Projects Supporting geodetic research and scholarly publications Functioning as a component of the Global Geodetic Observing System (GGOS) and member of the World Data System (WDS).
View
CubeSat's attitude determination using GNSS antenna array
Presentation
Full-text available
  • Dec 2022
The attitude information of a CubeSat is essential to keeping the satellite in its favourable orientations in the mission and sensor positioning using precise orbit determination. The attitude of CubeSats can be determined using sun sensors, magnetometers, and star trackers. However, these sensors have some issues, including unavailability in shadow for sun sensors, low accuracy for magnetometers, and additional costs for star trackers. In this study, we propose an alternative method for the CubeSats attitude determination using the GNSS observations of an antenna array. Fixing the estimated double-differenced ambiguities as integer values equips the model with precise phase observations. In addition, the known geometry of the antenna array in the CubeSats reference frame helps us apply the rotation matrix's orthonormality constraints between the estimated baselines and the known ones. To validate the model, the actual observations of a 3U CubeSat from the Spire constellation are used to determine its precise orbit. An array of 3 coplanar antennae is then simulated using the definition of CubeSat's reference frame, the available quaternions from the star tracker and the precise orbits of CubeSats and GNSS satellites. The results validate the proposed method by providing acceptable Yaw, Pitch and Roll angles. The proposed model has the advantage of applying to the single-frequency receiver onboard the 1U low-cost and low-power CubeSats.
View
LEO aiding GNSS positioning in challenging environments
Presentation
Full-text available
  • Sep 2022
Presented at FIG Congress 2022, 11-15 September 2022, Warsaw, Poland
View
Milestone 3 Presentation: Precise Orbit Determination (POD) of CubeSats
Presentation
Full-text available
  • Aug 2022
This is the final Presentation of my PhD project.
View
View
PhD Candidacy Presentation: Precise Orbit Determination of CubeSats
Presentation
Full-text available
  • Aug 2022
This is the presentation of Milestone 1 (Candidacy) at Curtin University
View
The impact of precise inter-satellite ranges on relative precise orbit determination in a smart CubeSats constellation
Conference Paper
Full-text available
  • May 2022
The use of CubeSats is expanding in space and earth science applications due to the low costs of building and the possibility of launching them in a large low-earth orbits (LEO) constellation. Such constellation can serve as an augmentation system for positioning, navigation and timing. However, real-time precise orbit determination (POD) is still one of the challenges for this application. Real-time reduced-dynamic POD requires more processing capability than what is available in current CubeSats, and the kinematic POD highly depends on the number and the quality of the signals from Global Navigation Satellite Systems (GNSS). In this study, an approach is proposed to increase the orbital accuracy by implementing the precise inter-satellite ranges in the Kinematic POD. The precise orbits of a set of CubeSats from the Spire Global constellation that are determined using the reduced-dynamic POD is to be used to generate the precise inter-satellite ranges. These ranges vary from hundreds to thousands of kilometres and are constrained in the relative kinematic POD between the tested CubeSats. The results, which depend on the length of the inter-satellite ranges, show the improvement of the orbital accuracy in all directions. An initial architecture for implementing such a method in a smart CubeSats constellation is proposed and the limitations and remedies are discussed.
View
International Doris Service (IDS): Data and Products
Presentation
Full-text available
  • Mar 2012
I introduced the international Doris Service in the internal seminars of the University of Isfahan. The Doris system is a french civil precise orbit determination and positioning system. It is based on the principle of the Doppler effect with a transmitting terrestrial beacons network and onboard instruments on the satellite's payload (antenna, radio receiver, and oscillator ultra-stable). Doris is one of three systems used for the precise determination of the Jason-1 satellite's orbit. Several of these techniques are sometimes merged on the same satellite: Jason-1 satellite includes three tracking systems, Doris, location by GPS, and laser telemetry. The Doris system perfectly corresponds to the specifications required for the ocean's topography observations and the amplitude of the observed phenomena: it is now enabled to measure the satellite position on its orbit close to 1 cm. It is interesting to compare this precision with the precision obtained at the beginning of the space age, where the satellite position was estimated close to 20 km then close to 20 meters in the '80s. Since 1998, the Diode navigator has added real-time measurement processing capability for satellite navigation. The Doris system was designed by CNES, the French space agency, in partnership with France's mapping and survey agency IGN and the space geodesy research institute GRGS. Since 2003, IDS is an international service that provides support, through Doris data and products. The successive missions since Spot 2 and Topex/Poseidon have truly demonstrated its performance.
View
A deep look at the International Laser Ranging Service (ILRS)
Presentation
Full-text available
  • Mar 2012
I introduced the International Laser Ranging Service (ILRS), its data and products in the internal student's seminar at the University of Isfahan: Satellite Laser Ranging (SLR) and Lunar Laser Ranging (LLR) use short-pulse lasers and state-of-the-art optical receivers and timing electronics to measure the two-way time of flight (and hence distance) from ground stations to retroreflector arrays on Earth-orbiting satellites and the Moon. Scientific products derived using SLR and LLR data include precise geocentric positions and motions of ground stations, satellite orbits, components of Earth’s gravity field and their temporal variations, Earth Orientation Parameters (EOP), precise lunar ephemerides, and information about the internal structure of the Moon. Laser-ranging systems are already measuring the one-way distance to remote optical receivers in space and can perform very accurate time transfer between sites far apart. Laser-ranging activities are organized under the International Laser Ranging Service (ILRS) which provides global satellite and lunar laser ranging data and their derived data products to support research in geodesy, geophysics, Lunar science, and fundamental constants. This includes data products that are fundamental to the International Terrestrial Reference Frame (ITRF), which is established and maintained by the International Earth Rotation and Reference Systems Service (IERS). The ILRS develops the necessary global standards/specifications for laser ranging activities and encourages international adherence to its conventions.
View
International GNSS Service (IGS): Structure, Data, and Products
Presentation
Full-text available
  • Mar 2012
I introduced the International GNSS Service in the internal students' seminar at the University of Isfahan: The International GNSS Service (IGS) has ensured open access, high-quality GNSS data products since 1994. These products enable access to the definitive global reference frame for scientific, educational, and commercial applications – a tremendous benefit to the public, and a key support element for scientific advancements. The IGS at a Glance A voluntary federation of over 200 self-funding agencies, universities, and research institutions in more than 100 countries; working together to provide the highest precision GPS satellite orbits in the world. Providing free and open access to the highest precision products available for scientific advancement and public benefit. These products support a wide variety of applications that touch millions of users in virtually all segments of the global economy Producing products that support the realization of the International Terrestrial Reference Frame while providing access to tracking data from over 400 worldwide reference stations Working for the continuous development of new applications and products through Working Groups and Pilot Projects Supporting geodetic research and scholarly publications Functioning as a component of the Global Geodetic Observing System (GGOS) and member of the World Data System (WDS).
View
Detect and Analysis of Noise with Different Combinations of Time Series in IGS Permanent Stations
Presentation
Full-text available
  • Jun 2011
In this project, I will demonstrate the process of analyzing GPS time-series data. I have used 10 years of continuous GPS measurements of four stations (ALGO, GRAZ, KOSG, and ONSA) and three different combinations of the noise component of GPS coordinate time-series, i.e., White noise, Flicker noise, and random walk noise. I use Least Squares Variance Component Estimation (LS-VCE) instead of Maximum Likelihood Estimation (MLE) because of its advantages.
View