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Format of Geo++ PCV Antenna File

Name

Geo++ antenna file

Description

The following text describes the format of the Geo++ antenna files. Antenna files may contain information on the three dimensional antenna phase center offsets and antenna phase and code center variations (PCV / GDV). The PCV  and GDV can be elevation dependent or both, elevation and azimuth dependent.

File Format

The format of the ant-file uses some keywords to indicate different data or general information. Comment lines are allowed and do have a '#' as the first sign of the line. However, comment lines are not allowed within the data sections (i.e. the lines of data which may follow the keyword VARIATIONS L1= and/or VARIATIONS L2=).

The meaning of the keywords is as follows. The '=' sign is part of the keyword and is not separated by a blank from the previous alphanumerical character.

Type=

is an alphanumerical description of the antenna type. The TYPE = entry generally contains the IGS Antenna Code and the IGS Antenna DOME Code. For more information please refer to the current rcvr_ant.tab

SERIAL NUMBER=

indicates the serial number of the antenna. In the case of a typemean the serial number will be blank.

 

CALIBRATION TYPE=

indicates weather the content of the antenna exchange file is "Individual" or "Typemean". Therefore the entries are "Individual" or "Typemean".

CALIBRATION DATE=

contains a string with the current date ofthe following format: yyyy-mm-ddZhh:mm:ss

NO OF ANTENNAS=

contains an interger value with the number of calibrated antennas w.r.t. the current GNSS entry.

NO OF CALIBRATIONS=

contains an integer values with the number of individual calibration w.r.t. the current GNSS entry.

GNSS TYPE=

Antenna reception properties for the observation types carrier-phase and code-phase are possible. The GNSS Type relates the content of the file to the specific GNSS system (GPS, GLONASS, Beidou, etc).

CONTENT TYPE=

defines the content of the Antenna exchange file. The file can contain Variations of the code-phase observation (Group Delay Variation GDV) or for the carrier-phase observation (PCV).

Example: CONTENT TYPE=PCV

PCV TYPE=

this entry type defines weather the file contains absolute (Robot/chamber based calibration) or relative (field calibration with AOAD/M_T as reference antenna) PCV values.

NO OF FREQUENCIES=

indicates the number of frequencies, which follow in the ant-file. For dual frequency antenna the entry is "2", for single frequency antenna "1".

OFFSETS L1=

contains the L1 offsets of the phase center in north, east and height component. The unit of the values is in meter [m]. The three numbers are separated by a blank.

Example: OFFSETS L1=+0.00000 +0.00000 +0.00000

OFFSETS L2=

contains the L2 offsets of the phase center in north, east and height component. The unit of the values is in meter [m]. The three numbers are separated by a blank, smae as above.

ELEVATION INCREMENT=

is the increment of the elevation dependent PCV. The PCV are listed in a table of a discrete increment for the elevation from 0 to 90 deg. The unit of the increments are degree [deg]. The increment can be individually selected, however, a common value for the ELEVATION INCREMENT= is 5 deg.

AZIMUTH INCREMENT=

is the increment of the azimuth dependent PCV. The PCV are listed in a table of a discrete increment for the elevation and azimuth from 0 to 90 deg and 0 to 360 deg. The unit of the increments are degree [deg]. The increment can be individually selected, however, a common value for the AZIMUTH INCREMENT= is 5 deg. Only elevation dependent PCV must specify "0" for the AZIMUTH INCREMENT=.

VARIATIONS L1=

is followed in the next line by the actual PCV values of L1. The first line contains the elevation dependent PCV for azimuth 0 deg. The number of PCV values within the line is determined by "columms: 90/(elevation increment)" and start from 0 deg to 90 deg. For just an elevation dependent data set, only one line of PCV is given. Additional azimuth dependent PCV follow in a new line. The corresponding number of lines is determined by "rows: 360/(azimuth increment)+1" and starts from 0 deg to 360 deg. However, the row for 0 deg has to be repeated for the 360 deg row.

VARIATIONS L2=

is followed in the next line by the actual PCV values of L2. The first line contains the elevation dependent PCV for azimuth 0 deg. The number of PCV values within the line is determined by "columms: 90/(elevation increment)" and start from 0 deg to 90 deg. For just an elevation dependent data set, only one line of PCV is given. Additional azimuth dependent PCV follow in a new line. The corresponding number of lines is determined by "rows: 360/(azimuth increment)+1" and starts from 0 deg to 360 deg. However, the row for 0 deg has to be repeated for the 360 deg row.

DEVIATIONS L1=

contains the RMS values for the specific frequency. The table is equal to the corresponding L1 VARIATIONS table.

DEVIATIONS L2=

contains the RMS values for the specific frequency. The table is equal to the corresponding L1 VARIATIONS table.

 

DIFFERENCES to IGS ANTEX FORMAT

The Geo++ antenna files are different to the IGS ANTEX format in the following aspects:

  • all values given in meter (instead of mm in IGS)
  • all parameters (offset and PCV) with the same sign convention (different to IGS)
  • sign of PCV (opposite to IGS)
  • PCV listed starting from 0 to 90 deg elevation (opposite to IGS)
  • contains GDV values (not yet possible in IGS ANTEX)

additional hints

The Geo++ sign of the PCV originates from the intention to have consistent corrections for offset and PCV. The offsets of the phase center (PC) are added. Therefore the PCV should be added to a range or phase range as well. This defines the sign of the Geo++ PCV convention, which is opposite to the IGS/NGS.