Hi Both the receiver and the antenna have filters in them. The "affordable" ones (no need to say cheap) are made from ceramics that have significant temperature coefficients. If you are getting -40 to +30C jumps, they will definitely have an impact on the filters phase / delay. That's going to make sub mm work pretty tough.
Bob -----Original Message----- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Attila Kinali Sent: Wednesday, April 25, 2012 10:57 AM To: time-nuts@febo.com Subject: [time-nuts] Sub mm measurements with gps timing antennas? Moin, We've a customer who does sub mm measurements using GPS in alpine enviroment. This is done using LEA-6T modules, logging of raw phase data and offline post processing using long averaging windows. Now, the customer had some problems reaching the precision requirements and i'm wondering whether one of the causes might be the use of a Trimble Bullet antenna [1] (3V type) and not a geodetic antenna. Can it be that the phase center of the Trimble Bullet antenna isn't as well defined as it should be for this application? Would the addional gain of the 5V version help (35dB instead of 30dB)? Or should we evaluate a different antenna all together. A major restriction in this application is that there is a very harsh enviroment, temperature wise. We have measured -40°C to +30°C jumps in just 2h. Most of the time the devices are below freezing temperature, but can go up to 50°C when in direct sunlight. The next big restriction is, that this is a research project. So there isn't as much money available as there should be to "do it right". So, if someone could give a few tips how to improve things, this would be much appreciated. Attila Kinali [1] http://www.trimble.com/timing/bullet-gps-antenna.aspx?dtID=overview& -- The trouble with you, Shev, is you don't say anything until you've saved up a whole truckload of damned heavy brick arguments and then you dump them all out and never look at the bleeding body mangled beneath the heap -- Tirin, The Dispossessed, U. Le Guin _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.