kb8tq@n1k.org said: > If indeed dual frequency GPS is part of the intended use, the survey > oriented gear will be slightly happier if the “right” corner faces north. What's in the antenna that makes North interesting? and/or how would a receiver take advantage of it? -- These are my opinions. I hate spam.

Hi The antenna has a measured / documented pattern (amplitude and more importantly phase). If you have it pointed in a known direction, that information can be used when post processing carrier phase information. If you are trying to get to mm / picosecond levels on an multi hour L1/L2 dataset, that sort of thing can be significant. Bob > On Jan 19, 2018, at 4:00 PM, Hal Murray <hmurray@megapathdsl.net> wrote: > > > kb8tq@n1k.org said: >> If indeed dual frequency GPS is part of the intended use, the survey >> oriented gear will be slightly happier if the “right” corner faces north. > > What's in the antenna that makes North interesting? and/or how would a > receiver take advantage of it? > > > > -- > These are my opinions. I hate spam. > > > > _______________________________________________ > 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.

> What's in the antenna that makes North interesting? and/or how would a > receiver take advantage of it? Hal, The people that work at the mm level get very picky about details; antenna reception is not perfectly symmetrical or centered or equal at every frequency or angle. There is a massive database of antenna calibrations here: https://www.ngs.noaa.gov/ANTCAL/ Click on "Browse Antenna Information by Manufacturer and Model", pick some vendor, and hover over Drawing, Label, Side, Top. Then see the raw data for the calibration. Here's a random example: https://www.ngs.noaa.gov/ANTCAL/LoadFile?file=TRM105000.10_NONE.atx Or view a 10 MB database: https://www.ngs.noaa.gov/ANTCAL/LoadFile?file=ngs14.atx See also: https://www.ngs.noaa.gov/ANTCAL/FAQ.xhtml Here's a couple of random links to give you an idea what this is all about: "How to Use IGS Antenna Phase Center Corrections" http://acc.igs.org/antennas/igs-pcvs_gpsworld10.pdf "ANTENNA PHASE CENTER VARIATIONS CORRECTIONS IN PROCESSING OF GPS OBSERVATIONS WITH USE OF COMMERCIAL SOFTWARE" http://www.uwm.edu.pl/wnt/technicalsc/tech_13/B12.PDF "Influence of GPS antenna phase center variation on precise positioning" https://www.sciencedirect.com/science/article/pii/S2090997713000515 "Satellite Antenna Phase Center Offsets and the Terrestrial Scale" http://www.igs.org/assets/pdf/W2016%20-%20PY0703%20-%20Rothacher.pdf That will keep you busy for a while. /tvb