20 September 2006 ANTEX: The Antenna Exchange Format Version 1.3 ********************************************** M. Rothacher, R. Schmid Forschungseinrichtung Satellitengeodäsie TU München 1. VERSION 1.3 MODIFICATIONS The modifications leading to Version 1.3 include: - definition of the frequency number codes (1.3) - clarification of the satellite-fixed coordinate system (1.3) - IGS naming convention (1.3) - definition of the antenna corrections (1.3) - optional SVN number and COSPAR ID (1.3) - comments and references (1.3) - serial number for reference antenna (1.2) - new calibration method ROBOT (1.2) - clarification of several descriptions (1.2) - antenna-specific SINEX CODE (1.1) - COMMENT description (1.1) 2. FILE EXTENSION We recommend using 'atx' as file extension. For official IGS models the following naming convention is used: mmmmm_wwww.atx | | | +------- wwww: GPS week of the last file change | +------------ mmmmm: 5-character model name (will only be changed, if existing values are changed) 3. DEFINITION OF THE ANTENNA CORRECTIONS In order to clarify the sign convention, the following shortened formulae are given: RECEIVER ANTENNA: phase center position = ARP (antenna reference point) position + phase center offset (given in a topocentric left-handed system: north, east and up component) observed distance = geometric distance + phase center variations (zenith, azimuth) + other corrections (Here the azimuth counts clockwise from the North toward the East.) SATELLITE ANTENNA: phase center position = CM (center of mass) position + phase center offset (The phase center offset is given in a satellite-fixed right-handed coordinate system: - z-axis points toward the geocenter - y-axis (rotation axis of the solar panels) corresponds to the cross product of the z-axis with the vector from the satellite to the Sun - x-axis completes the right-handed system (x cross y = z) In addition, the yaw attitude has to be considered during eclipse seasons when the Sun sensors fail.) observed distance = geometric distance + phase center variations (nadir, azimuth) + other corrections (Here the azimuth counts clockwise from the y-axis toward the x-axis when looking toward the z-axis.) 4. ANTEX VERSION 1.3 FORMAT DEFINITIONS +--------------------+------------------------------------------+------------+ | HEADER LABEL | DESCRIPTION | FORMAT | | (Columns 61-80) | | | +--------------------+------------------------------------------+------------+ |ANTEX VERSION / SYST| - Format version (1.3) | F8.1,12X, | | | - Satellite System: blank or 'G': GPS | A1,39X | | | 'R': GLONASS | | | | 'E': Galileo | | | | 'M': Mixed | | +--------------------+------------------------------------------+------------+ |PCV TYPE / REFANT | - Phase center variation type: | A1,19X, | | | 'A': absolute values | | | | 'R': relative values | | | | - Reference antenna type for relative | A20, | | | values (blank: AOAD/M_T) | | | | - Serial number (blank: all representa- | A20 | | | tives of the specified antenna type) | | +--------------------+------------------------------------------+------------+ *|COMMENT | Comment line(s) | A60 |* | | (only allowed at the specified position) | | +--------------------+------------------------------------------+------------+ |END OF HEADER | Last record in the header section. | 60X | +--------------------+------------------------------------------+------------+ |START OF ANTENNA | Record indicating the start of an antenna| 60X | | | section. | | +--------------------+------------------------------------------+------------+ |TYPE / SERIAL NO | Receiver antenna: | | | | - Antenna type: strict IGS | A20, | | | rcvr_ant.tab antenna and radome code | | | | - Serial number (blank: all representa- | A20, | | | tives of the specified antenna type) | | | | - blank | A10, | | | - blank | A10 | | | Satellite antenna: | | | | - Antenna type: strict IGS | | | | rcvr_ant.tab satellite antenna code | | | | Example: 'BLOCK IIA' | | | | - Satellite code "CNN" (blank: all | | | | representatives of the specified | | | | antenna type) | | | | For the selection of single satellites| | | | the satellite system flag (blank,'G', | | | | 'R','E') together with the PRN number | | | | (GPS) or the slot number (GLONASS) has| | | | to be specified. | | | | Example: 'G05' | | | | - Satellite code "CNNN" (optional) | | | | C - satellite system flag | | | | NNN - SVN or GLONASS number | | | | - COSPAR ID "YYYY-XXXA" (optional) | | | | YYYY - year of when the launch vehicle| | | | was put in orbit | | | | XXX - sequential launch vehicle | | | | number for that year | | | | A - alpha numeric sequence number | | | | within a launch | | +--------------------+------------------------------------------+------------+ |METH / BY / # / DATE| - Calibration method: | A20, | | | 'CHAMBER', 'FIELD', 'ROBOT', | | | | 'COPIED' from other antenna, | | | | 'CONVERTED' from igs_01.pcv or blank | | | | - Name of agency | A20, | | | - Number of individual antennas | I6,4X, | | | calibrated | | | | - Date | A10 | +--------------------+------------------------------------------+------------+ |DAZI | Increment of the azimuth: | 2X,F6.1, | | | 0 to 360 with increment 'DAZI' | 52X | | | (in degrees). | | | | 360 degrees have to be divisible by | | | | 'DAZI'. | | | | Common value for 'DAZI': 5.0 | | | | For non-azimuth-dependent phase center | | | | variations '0.0' has to be specified. | | +--------------------+------------------------------------------+------------+ |ZEN1 / ZEN2 / DZEN | Receiver antenna: | 2X,3F6.1, | | | Definition of the grid in zenith: | 40X | | | 'ZEN1' to 'ZEN2' with increment 'DZEN' | | | | (in degrees). | | | | 'ZEN1' and 'ZEN2' always have to be | | | | multiples of 'DZEN'. | | | | 'ZEN2' always has to be greater than | | | | 'ZEN1'. | | | | Common value for 'DZEN': 5.0 | | | | Example: ' 0.0 90.0 5.0' | | | | Satellite antenna: | | | | Definition of the grid in nadir: | | | | 'ZEN1' to 'ZEN2' with increment 'DZEN' | | | | (in degrees). | | | | 'ZEN1' and 'ZEN2' always have to be | | | | multiples of 'DZEN'. | | | | 'ZEN2' always has to be greater than | | | | 'ZEN1'. | | | | Common value for 'DZEN': 1.0 | | | | Example: ' 0.0 14.0 1.0' | | +--------------------+------------------------------------------+------------+ |# OF FREQUENCIES | Number of frequencies, for which phase | I6,54X | | | patterns are stored for the current | | | | antenna. | | +--------------------+------------------------------------------+------------+ *|VALID FROM | Start of validity period in GPS time | 5I6,F13.7, |* | | (4-digit-year,month,day,hour,min,sec) | 17X | +--------------------+------------------------------------------+------------+ *|VALID UNTIL | End of validity period in GPS time | 5I6,F13.7, |* | | (4-digit-year,month,day,hour,min,sec) | 17X | +--------------------+------------------------------------------+------------+ *|SINEX CODE | Name of the antenna calibration model to | A10,50X |* | | be used in the SINEX format (for | | | | referencing purposes) | | +--------------------+------------------------------------------+------------+ *|COMMENT | Comment line(s) | A60 |* | | (only allowed at the specified position) | | +--------------------+------------------------------------------+------------+ |START OF FREQUENCY | Record indicating the start of a new |3X,A1,I2,54X| | | frequency section. The satellite system | | | | flag (blank,'G','R','E') has to be | | | | specified together with the frequency | | | | number code that has to be consistent | | | | with the RINEX definition: | | | | GPS: 'G01' - L1 | | | | 'G02' - L2 | | | | 'G05' - L5 | | | | GLONASS: 'R01' - G1 | | | | 'R02' - G2 | | | | Galileo: 'E01' - E1 | | | | 'E05' - E5a | | | | 'E07' - E5b | | | | 'E08' - E5 (E5a+E5b) | | | | 'E06' - E6 | | | | The frequency section includes the | | | | eccentricities of the antenna phase | | | | center and the phase pattern values. | | | | Neither other types of records nor | | | | comment lines are allowed within this | | | | section. | | +--------------------+------------------------------------------+------------+ |NORTH / EAST / UP | Receiver antenna: | 3F10.2,30X | | | Eccentricities of the antenna phase | | | | center relative to the antenna reference| | | | point (ARP). North, east and height | | | | component (in millimeters). | | | | Satellite antenna: | | | | Eccentricities of the antenna phase | | | | center relative to the center of mass of| | | | the satellite in X-, Y- and Z-direction | | | | (in millimeters). | | +--------------------+------------------------------------------+------------+ |(Values of a non- | The flag 'NOAZI' denotes a non-azimuth- | 3X,A5,mF8.2| |azimuth-dependent | dependent pattern that has to be | | |pattern) | specified in any case (also if 'DAZI' > | | | | 0.0). | | | | Phase pattern values in millimeters from | | | | 'ZEN1' to 'ZEN2' (with increment 'DZEN').| | | | All values on one line. | | +--------------------+------------------------------------------+------------+ *|(Values of an | The azimuth-dependent pattern has to be | F8.1,mF8.2 |* |azimuth-dependent | specified, if 'DAZI' > 0.0. The first | | |pattern) | value in each line denotes the azimuth | | | | angle followed by the phase pattern | | | | values in millimeters from 'ZEN1' to | | | | 'ZEN2' (with increment 'DZEN'). | | | | All values of one azimuth angle on one | | | | line. | | +--------------------+------------------------------------------+------------+ |END OF FREQUENCY | Record indicating the end of a frequency |3X,A1,I2,54X| | | section (see also 'START OF FREQUENCY'). | | +--------------------+------------------------------------------+------------+ *|START OF FREQ RMS | Record indicating the start of an rms |3X,A1,I2,54X|* | | value section related to the specified | | | | frequency. | | | | The section includes the rms values of | | | | the phase center eccentricities and of | | | | the phase pattern values. | | | | Neither other types of records nor | | | | comment lines are allowed within this | | | | section. | | +--------------------+------------------------------------------+------------+ *|NORTH / EAST / UP | Rms of the eccentricities (in milli- | 3F10.2,30X |* | | meters). | | +--------------------+------------------------------------------+------------+ *|(Rms values of the | The flag 'NOAZI' denotes the rms values | 3X,A5,mF8.2|* |non-azimuth- | of the non-azimuth-dependent pattern. | | |dependent pattern) | Phase pattern rms values in millimeters | | | | from 'ZEN1' to 'ZEN2' (with increment | | | | 'DZEN'). | | | | All values on one line. | | +--------------------+------------------------------------------+------------+ *|(Rms values of the | Rms values of the azimuth-dependent | F8.1,mF8.2 |* |azimuth-dependent | pattern, if 'DAZI' > 0.0. The first | | |pattern) | value in each line denotes the azimuth | | | | angle followed by the phase pattern rms | | | | values in millimeters from 'ZEN1' to | | | | 'ZEN2' (with increment 'DZEN'). | | | | All values of one azimuth angle on one | | | | line. | | +--------------------+------------------------------------------+------------+ *|END OF FREQ RMS | Record indicating the end of an rms value|3X,A1,I2,54X|* | | section (see also 'START OF FREQ RMS'). | | +--------------------+------------------------------------------+------------+ |END OF ANTENNA | Record indicating the end of an antenna | 60X | | | section. | | +--------------------+------------------------------------------+------------+ Records marked with * are optional 5. COMMENTS - For information on GPS satellites (SVN, PRN, etc.) please refer to ftp://tycho.usno.navy.mil/pub/gps/gpsb1.txt and ftp://tycho.usno.navy.mil/pub/gps/gpsb2.txt or http://gge.unb.ca/Resources/GPSConstellationStatus.txt - For information on GLONASS satellites (GLONASS number, slot number, etc.) please refer to http://www.glonass-ianc.rsa.ru/ - For COSPAR IDs please refer to http://www.aiub.unibe.ch/download/BSWUSER50/GEN/SATELLIT. or http://ilrs.gsfc.nasa.gov/satellite_missions/list_of_satellites/glonass/ - For IGS standard antenna names please refer to ftp://igscb.jpl.nasa.gov/igscb/station/general/rcvr_ant.tab - For further antenna calibration results please refer to http://www.ngs.noaa.gov/ANTCAL/ or http://gnpcvdb.geopp.de/ 6. REFERENCES Rothacher, M., G. Mader (2003): "Receiver and satellite antenna phase center offsets and variations." In: Tétreault, P., R. Neilan, K. Gowey (eds.) Proceedings of the Network, Data and Analysis Centre 2002 Workshop, pp. 141-152, Ottawa. (http://igscb.jpl.nasa.gov/igscb/resource/pubs/02_ott/session_8.pdf) Schmid, R., G. Mader, T. Herring (2005): "From relative to absolute antenna phase center corrections." In: Meindl, M. (ed.) Proceedings of the IGS Workshop and Symposium 2004, Berne. (http://igscb.jpl.nasa.gov/igscb/resource/pubs/04_rtberne/Session10_1.pdf)