Subject: [IGS-AWG-15] Re: [IGS-AWG-9] Miami Workshop: Antenna recommendations From: Ralf Schmid Date: Thu, 19 Jun 2008 10:45:22 +0200 To: igs-awg@igscb.jpl.nasa.gov ****************************************************************************** IGS-AWG Mail 19 Jun 01:45:28 PDT 2008 Message Number 15 ****************************************************************************** Dear colleagues! As regards the workshop recommendations, I received two comments: 1) Carine wanted to know whether we would allow individual calibrations within the IGS. As this is not my intention, recommendation 1 now asks for the provision of "an absolute type calibration" ("type" added). 2) Rolf mentioned that the SINEX format description contained blocks for GPS (SITE/GPS_PHASE_CENTER) and Galileo (SITE/GAL_PHASE_CENTER) receiver antenna corrections, but not for GLONASS. However, with view to recommendation 7, it is important to have such a block. Thus, recommendation 5 was extended. That means that you can find the final (from the point of view of our working group) version of the recommendations below. Those recommendations should be distributed among the GB members for final approval. I hope, Jim or Gerry can take care of that. Best regards, Ralf 1. At IGS stations, it should no longer be allowed to install antenna types or antenna/radome combinations that are not absolutely calibrated. If a new station is set up or an old antenna is replaced, station operators are asked to choose an antenna type that shows a robot calibration (or the consistent results of a different calibration procedure of comparable quality) within the IGS antenna calibration file or to provide an absolute type calibration. (An exception could only be made for those antenna types that are already in use within the IGS and whose calibration values cannot be updated for that reason.) 2. It should be avoided to add additional converted field calibrations to the absolute IGS antenna correction file. Exceptions may be calibrations for antenna/radome combinations that are already in use within the IGS. NGS is encouraged to provide its calibrations in the ANTEX format. 3. z-offsets for newly launched satellites are estimated from weekly SINEX files. At least half a year of data should be available. The Analysis Centers are encouraged to add (constrained) phase center offset estimates to their SINEX files. Major prerequisite for new individual z-offsets is the consistency with the offsets contained in the operational model. 4. Before the start of a new reprocessing campaign, the absolute antenna correction file has to be updated with all available robot calibrations as well as with z-offsets (and PCVs) for the latest satellites from an analysis of weekly SINEX files. 5. The SINEX format has to be extended in order to allow for satellite antenna phase center variation estimates and for GLONASS receiver antenna phase center corrections (additional SITE/GLO_PHASE_CENTER Block). 6. The IGS Antenna Working Group as well as the Analysis Centers are encouraged to analyze azimuth-dependent phase center variations of the satellite antennas as well as differences between the 'horizontal' offsets (x, y) of individual satellites. It is an ultimate goal to combine ground- and space-based satellite antenna maps in order to make profit of the azimuth-dependence and the bigger maximum nadir angle. JPL is encouraged to provide its maps in the ANTEX format. 7. The next major revision of the absolute IGS antenna correction file will contain receiver antenna calibrations for the mean GLONASS frequencies. The Antenna Working Group will check their correctness. The Analysis Centers should be prepared to use such values. 8. The Antenna Working Group should investigate the feasibility of group delay calibrations.