Equipment & Calibration
Equipment accepted within the EPN
The GNSS equipment used at the EPN stations complies with the EUREF standards. This means that :
- the GNSS receiver
and antenna must be known to the IGS and included in the receiver/antenna table
(rcvr_ant.tab file). This table contains the IGS/EPN naming conventions
for GNSS equipment (receivers, antennas, radomes, satellite antennas); they are the only valid names to be used in IGS station logs,
RINEX headers, SINEX files, etc. Checklist for including new entries in rcvr_ant.tab.
A description of the antenna (physical dimensions and antenna reference point (ARP) definition) is given in the antenna.gra file.
- the receiver and antenna should at least allow dual frequency geodetic-type GNSS observations.
- the antenna+radome pair should have zenith and azimuth-dependent absolute calibration values down to the horizon available from the EPN Central Bureau (antenna/radomes fulfilling this requirement).
The usage of antenna radomes is discouraged, but not forbidden.
Antenna/radome calibrations used by the EPN
The antenna calibrations used within the EPN are given in the epn_14.atx file (in usage since January 30, 2017),
available in the standard format used to exchange antenna calibrations, the ANTEX format.
This file contains :
- The individual antenna calibrations used within the EPN, available from the EPN CB, and given in the file epnc_14.atx. For more details, see EUREF mail 03020.
- The antenna calibration values used within the IGS, available from the IGS Central Bureau, and given in the igs14.atx file (linking to the file igs14_wwww.atx, with wwww the GPS week of the last file change).
Type calibration values are applied in case no individual absolute calibrations are available. If no individual nor type calibrations are available
for a specific antenna+radome combination, then the calibrations for the
corresponding antenna without a radome (radome code: NONE) should be applied.
The map shows for each EPN station what kind of absolute antenna/radome calibrations are available. Black stations have antenna/radome pairs with absolute individual calibrations (42.23%), green have antenna/radome pairs with absolute type calibrations (55.31%), orange have antenna/radome pairs with absolute calibrations converted from relative values (0.27%), and red have antenna/radome pairs without absolute calibrations (2.18%). In this case, the radome is neglected and the calibration values of the antenna with radome 'NONE' is used.
The long-term goal of EUREF is to eliminate the red and yellow dots from this map and to have a network with antenna+radome equipment which all have absolute ('individual' or 'type') calibrations freely available from the EPN Central Bureau. To achieve this goal, new antenna+radome pairs introduced in the EPN (new stations or replacements at existing stations) should, with some exceptions, be individually calibrated or have absolute calibrations available from the IGS. More details are available in "Procedure for Becoming an EPN Station" and "Guidelines for EPN Stations and Operational Centres".