[FOSS-GPS] rtklib: antenna models and how to create them

[Homan, Thomas]

Hi Timo,

This list is generated and maintained by the US National Geodetic Survey. A link to their methodology can be found at http://www.ngs.noaa.gov/ANTCAL. Select the 'GPS Antenna Calibration at the National Geodetic Survey' PDf file to read on their methods. Adding your inexpensive antenna model would be expensive if you follow the NGS method. If you don't follow the NGS method then your results will likely be off and the fit might be worse. 

That being said, my understanding of the calibration model is that it corrects primarily in the vertical component of the measurement. In working with survey grade receivers, my understanding is that if the wrong antenna model is used the vertical error can be up to 10cm. So if you had some high accuracy survey points, you could possibly get closer through trial and error on the offset components. I have not read up on the phase components. 

Also, I noticed that Tomoji's list is out of date by a few years (2007/Mar/20) based on the download of the 2.4.0 source code. The current list dated Oct 19, 2010 has 311 antenna models so I would suggest getting the most current one from ftp://ftp.ngs.noaa.gov/pub/pnt6/ant_info.003 and renaming the file to ngs_abs.pcv then recompiling. Your stated 'cheap' antenna is probably not in there but it's worth a try.

Regards,

Tom
-----Original Message-----
From: foss-gps-bounces at lists.osgeo.org [mailto:foss-gps-bounces at lists.osgeo.org] On Behalf Of Timo Juhani Lindfors
Sent: Monday, November 22, 2010 10:00 AM
To: Open Source GPS-related discussion and support
Cc: Tomoji TAKASU
Subject: [FOSS-GPS] rtklib: antenna models and how to create them

Hello Tomoji,

rtklib-2.4.0/data/ngs_abs.pcv seems to contain antenna models for 229
different antennas. Were these imported from some public database?

Is there some procedure that I could follow to create an antenna model
for my extremely cheap antenna?

best regards,
Timo Lindfors
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