1. General questions
1.1. What is the EPN ?
1.2. What isn't the EPN ?
1.3. What is GNSS ?
1.4. What is the status of the GPS satellite constellation ?
1.5. What is the status of the GLONASS satellite constellation ?
1.6. Can you verify whether a local GPS outage or anomaly occurred ?
1.7. What could I read, to learn about the EPN ?
1.8. How is the EPN funded ?
1.9. What is the relation of the EPN to the global IGS network ?
1.10 Where can I find the IGS precise satellite orbits ?
2. EPN Data and Products
2.1 What is the difference between "data" and "products?" How do I get them ?
2.2 Are there costs or restrictions to the usage of data and products ?
2.3 What formats does the EPN use ?
2.4 What are the EPN products ?
2.5 What software, models, and conventions do the EPN Analysis Centres use ?
2.6 What reference frames were used during what periods? How do I transform between them ?
3. Stations
3.1 What is an EPN station ?
3.2 What is a station site log ?
3.3 May I propose a new EPN station and how do I proceed ?
3.4 Where can I find coordinate/velocity solutions for a site ?
3.5 How do I transform station coordinates to another reference frame ?
3.6 How do I stay informed about station status and performance ?
3.7 How do I check the latency of the hourly observation data from my EPN station ?
3.8 How can I check which Analysis Centres are processing the data from my EPN station ?
3.9 How can I update the site log of my station ?
3.10 How is the antenna height of an EPN station measured ?
3.11 How do I handle a change in the GNSS monument of my EPN station ?
4. Equipment
4.1 What equipment is acceptable for use in the EPN ?
4.2 Does the EPN endorse equipment ?
4.3 Does the EPN certify equipment as meeting the guidelines ?
4.4 What is the rcvr_ant.tab file and how can I request an update ?
4.5 What is the igs_01.pcv file and how can I request an update ?
4.6 What is the epn_05.atx file, why does it differ from the igs05.atx and how can I request an update?
4.7 Does inclusion in the rcvr_ant.tab naming table mean the equipment may be used in the EPN ?
5. Central Bureau web site
1. General questions
1.1. What is the EPN ?The EPN (or EUREF Permanent Network) is a voluntary organization of several European agencies and universities that pool resources and permanent GNSS station data to generate precise GNSS products. The EPN has been created under the umbrella of the International Association Geodesy and more precisely by its sub-commission EUREF.
1.2 What isn't the EPN ?The EPN does not manufacture or sell any equipment. It also does not endorse equipment (although the EPN has functional requirements for the GNSS equipment at EPN sites specified in the Guidelines for EPN stations and Operational Centres).
1.3 What is GNSS ?GNSS stands for Global Navigation Satellite System. Currently operating GNSS's are GPS (U.S.A.'s Global Positioning System) and GLONASS (Russia's Global Navigation Satellite System). Another GNSS planned for the future is Europe's Galileo.
1.4 What is the status of the GPS satellite constellation ?
This is provided by the U.S Coast Guard's Navigation Centre.
This is provided by the GLONASS centre.
1.6 Can you verify whether a local GPS outage or anomaly occurred ?You are welcome to browse our European network data and see if nearby EPN stations were recording data from the GPS satellites. Reports of GPS problems are accepted by the U.S Coast Guard's Navigation Centre.
1.7 What could I read, to learn about the EPN ?-
Bruyninx C., M. Becker and G. Stangl, 2001, "Regional Densification of the IGS in Europe Using the EUREF Permanent GPS Network (EPN)", Phys. Chem. Earth, Vol. 26, No 6-8, pp.531-538
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Adam J., W. Augath, C. Boucher, C. Bruyninx, A. Caporali, E. Gubler, W. Gurtner, H. Habrich, B. Harsson, H. Hornik, J. Ihde, A. Kenyeres, H. van der Marel, H. Seeger, J. Simek, G. Stangl, J. Torres, G. Weber, 2002, "Status of the European Reference Frame - EUREF", International Association of Geodesy Symposia, IAG Scientific Assembly, Springer, ed. J. Adam and K.-P. Schwarz, Vol. 125, pp 42-46
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Bruyninx C., 2004, "The EUREF Permanent Network: a multi-disciplinary network serving surveyors as well as scientists", GeoInformatics, Vol 7, pp. 32-35
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Kenyeres A. and Bruyninx C., 2004, "Monitoring of the EPN Coordinate Time Series for Improved Reference Frame Maintenance", GPS solutions, Vol 8, No 4, pp. 200-209
An extensive number of papers related to the EPN is available from the EPN CB.
1.8 How is the EPN funded ?Each participating organization voluntarily brings its own funding according to its own mission. These organizations tend to be public or government institutions or other research organizations. Consequently, the EPN requires redundancy and multi-year commitments to ensure reliability. To help EPN agencies justify funding requests, we request that users include a citation when use of EPN data or products results in a publication. We suggest
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Bruyninx C., 2004, "The EUREF Permanent Network: a multi-disciplinary network serving surveyors as well as scientists", GeoInformatics, Vol 7, pp. 32-35
The International GNSS Service (IGS)
is a voluntary federation of worldwide agencies that pool
resources and permanent GNSS station data to generate precise GNSS products.
In general, you can think of the IGS as the highest-precision international civilian GNSS community (source: IGS CB).
The EPN is a dense regional network GNSS network that operates following IGS standards. In addition, the IGS considers
the EPN as a related network and IGS works closely with the agencies operating the EPN.
Typically, the IGS designates a subset of the regional EPN stations as IGS stations. The choice of which stations should
also be IGS stations is motivated by their benefit to the IGS
products,
according to location and instrumentation.
Next to this, the EPN uses IGS products (such as the
IGS precise satellite orbits
for the generation of the EPN products).
Precise satellite orbits are made available by the IGS. Check the IGS web-site and more specific the page where you can download ephemeris.
2. EPN Data and Products
2.1 What is the difference between "data" and "products?" How do I get them ?
By "data" we mean raw GPS/GLONASS pseudorange and phase observations, broadcast ephemerides, and supporting types
of raw data (such as meteorological) as they are gathered by the permanent tracking sites.
We use the term "products" for things like the precise estimated site coordinates, tropospheric zenith path delays
and the coordinate time series. The products are generated through analysis of the raw site data.
Both raw data and
EPN products
are available from the
EPN Data Centres
and/or the Central Bureau.
The EPN has an open data policy. All observation data and products are available without charge
from the EPN data centres and/or Central Bureau.
Although the EPN strives for the highest quality of data and data products, it can not make any
warranty, express or implied, or assume any legal liability or responsibility for the accuracy,
completeness or usefulness of any information or product. Use of the EPN data and products is the
sole responsibility of the user.
When your use of EPN data or products results in a publication, please include a citation. We suggest
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Bruyninx C., 2004, "The EUREF Permanent Network: a multi-disciplinary network serving surveyors as well as scientists", GeoInformatics, Vol 7, pp. 32-35
The EPN uses exactly the same formats as the IGS does. See the IGS list.
2.4 What are the EPN products ?
The EPN products are described at the
"Products" web page.
EPN products are formed from a combination of results submitted by the EPN Analysis Centres. In this way,
the EPN products benefit in precision, accuracy, stability, reliability, and robustness compared to the results of any
individual AC.
See the files in ftp://epncb.oma.be/epncb/center/analysis/, which are submitted by the ACs.
2.6 What reference frames were used during what periods? How do I transform between them ?The web page describing the Combined EUREF Solution lists the different reference frames. Transformation formula between the frames are available from the ITRF web page's Transformation Parameters page http://itrf.ensg.ign.fr/trans_para.php.
3. Stations
3.1 What is an EPN station ?An EPN station conforms to the "Guidelines for EPN stations and Operational Centres" and is listed on EPN network maps and lists.
3.2 What is a station site log ?
Each user of the GNSS observation data from an EPN station requires a minimal amount of information about the station
such as its location, the GNSS equipment used, its monumentation, possible co-locations with other instruments and
addresses of site operators. The site log is the file that maintains all this information (including the history)
in a machine readable format. Having a valid site log is a minimal requirement for each EPN station.
Examples of station site logs are available from the EPN CB.
If the station is expected to be beneficial to an EPN product or project, please do. Visit the "Procedure for becoming an EPN station" and follow the instructions.
3.4 Where can I find coordinate/velocity solutions for a site ?Approximate coordinates for each site are listed on the station site log. Precise coordinates, in the ITRF reference frame, are available from the ITRF. Weekly station solutions in SINEX format can be retrieved from the weekly combined EUREF SINEX solution (see Products web page). An overview of available ITRS and ETRS89 coordinates for all EPN stations is available from the EPN CB's coordinates web-page.
3.5 How do I transform station coordinates to another reference frame ?See Question 2.7. Transformation formula between the ITRS and ETRS89 are available from the ITRF web page's Transformation Parameters page http://itrf.ensg.ign.fr/trans_para.php.
3.6. How do I stay informed about station status and performance ?At the EPN CB, each site has a web page reachable from the clickable map and station list. This page displays data availability and latency (for both the hourly and daily data submissions), errors in the header of the RINEX observation files, coordinate time series and data quality plots.
3.7 How do I check the latency of the hourly observation data from my EPN station ?See Question 3.6
3.8 How can I check which Analysis Centres are processing the data from my EPN station ?Have a look at the table "Who is processing which stations ?". Contact persons for each analysis centre can be found on the page where the EPN Analysis Centres are described.
3.9 How can I update the site log of my station ?
The EPN Central Bureau has an automated site log submission procedure. This procedure allows to quickly process incoming
mails that contain a site log in their mail body; it checks the validity of the site log and includes it in the
EPN data base. Check out the site log
submission instructions
before using this system.
If your EPN station is also part of the IGS, the updated site log should also be submitted to the IGS Central Bureau.
The antenna height of a station is the vertical height difference between the antenna marker on the ground and the
Antenna Reference Point (ARP). The file
antenna.gra
describes for each antenna used within the IGS and EPN the conventional Antenna Reference Point that should be used to
determine the antenna height.
The antenna.gra file is maintained by the IGS Central Bureau.
If the GNSS site is moved to a new monument (eg because of a destruction of the old monument), then a new DOMES number must be requested from the IERS and a new 4-char ID is required. It is imperative to contact the EPN CB in order to decommission the EPN station on the old marker and propose a new EPN station, with the new 4-char ID and new DOMES number, for introduction in the EPN.
4. Equipment
4.1 What equipment is acceptable for use in the EPN ?See the Guidelines for EPN stations and Operational Centres and the more specific web-page on EPN equipment and calibration.
4.2 Does the EPN endorse equipment ?No, the EPN maintains vendor neutrality and instead publishes functional requirements.
4.3 Does the EPN certify equipment as meeting the guidelines ?We do not issue certifications, but we can ask an EPN analyst to examine sample data sets from new equipment types and comment.
4.4 What is the rcvr_ant.tab file and how can I request an update ?
To be sure everyone recognizes the type of GNSS observation equipment used in at a GNSS observation site,
the IGS defines standard names for the different GNSS equipment (antennae, receivers, radomes) available today.
The rcvr_ant.tab file contains the list of these standard names. Since the EPN uses the same standards as the IGS,
it also uses the same naming conventions. These conventions are used in the files of the GNSS observation data
files and the IGS and EPN products.
The rcvr_ant.tab
file is maintained by the IGS Central Bureau. Requests for updates should be sent to the
IGS Central Bureau with a copy to the EPN Central Bureau.
The igs05.pcv file contains the absolute phase eccentricity values (pcv) of the antennae used within the IGS. These phase eccentricity values are given relative to a reference antenna.
The igs05.pcv file is maintained by the IGS Central Bureau. Requests for updates should be sent to
IGS Central Bureau with a copy to the EPN Central Bureau.
The epn_05.atx file contains with the absolute antenna phase centre calibrations for all the EPN stations; it merges the individual
antenna calibrations and the calibrations available from the IGS in the file igs05.atx. Access to the file is provided through ftp.
Username and password can be requested from
http://epncb.oma.be/_trackingnetwork/equipment_calibration/ind_ant_cal.php.
Different to the IGS, EUREF has decided to take advantage of the fact that several EPN stations have
absolutely calibrated their antenna+radome equipment (see EUREF mail 3020). If available, EUREF will
used these 'individual' calibrations for modeling the antenna phase center of the EPN stations. For
stations that do not have individual absolute calibrations, the EPN will use the absolute calibration
values made available by the IGS.
epn_05.atx is the official table to be used in the EPN analysis, while igs_01.pcv is the official table
to be used inthe IGS analysis.
To include an individual antenna calibration in epn_05.atx, contact the EPN Central Bureau. To update the igs05.atx file, see 4.5.
More details can be found here.
Not necessarily. The Guidelines for EPN stations and Operational Centres establish functional requirements for equipment in the EPN network.
5. Central Bureau web site
5.1 How view under Windows OS a 'current site log' from the individual site information web page(e.g. http://www.epncb.oma.be/_trackingnetwork/siteinfo4onestation.php?station=BRUS_13101M004) ?
In the control panel (Folder options) of the Windows operating system, the file type LOG is probably associated with an editor like "Wordpad". If you disable this association, then the log file will be opened directly in your browser.
EPN Central Bureau - Royal Observatory of Belgium