Yo Udo! On Wed, 15 Aug 2018 15:12:04 +0200 Udo van den Heuvel via devel <devel@ntpsec.org> wrote:
> Question: So what antenna would we need?
>
> One that covers multi GNSS, i.e.: GPS, Glonass, Galileo, Beidou, etc,
> etc.
Much easier said than done. Technically GPS L1 and GALILEO E1 use the
same frequency:
1.575.42MHz
GPS L1 bandwitdh is 15.345 MHz. GALILEO E1 is 12 MHz. So a GPS should
work fine w GPS. Right?
GALILEO uses a suppressed carrier. Most of the GPS signal is
close to the carrier.
To improve their performance some GPS antennas actually have a badnwidth
closer to 2 MHz and thus filter out GALILEO.
BeiDou B1 is down at 1.561 GHz. So that needs a GPS antenna of large
bandwidth.
Only way to tell is to try an antenna. I have many seemingly identical
GPS antennas that perform very differently. "High end" often means
narrow bandwidth and you do not want that.
Here is a list of the bands used:
http://www.rfwireless-world.com/Terminology/GPS-Frequency-Band-and-GNSS-Frequency-Band.html
And a nice graph:
https://www.labsat.co.uk/index.php/en/applications/labsat-frequency-guide
GLONASS is spread around. In thhe region of 1.600 up to 1602 GHz.
I have good luck with cheap GPS+GLONASS antennas for
GPS+GALILEO+GLOASS+BeiDou.
I you are lucky to have an L2, L3 or L5 GPS receiver, pretty rare, then
a wideband 1.150GHz to 1.61 Ghz will get you everything. An expensive
L1/L2 antenna will not get GLONASS.
u-blox has an app note:
https://www.u-blox.com/sites/default/files/products/documents/GPS-Antenna_AppNote_%28GPS-X-08014%29.pdf
In Section 5.1.1 they recommend a 50mmm to 70mm square ground plane
under a patch antenna. They do not recommend anything larger then
100mm (4").
RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
g...@rellim.com Tel:+1 541 382 8588
Veritas liberabit vos. -- Quid est veritas?
"If you can’t measure it, you can’t improve it." - Lord Kelvin
pgp2JunKfFlF3.pgp
Description: OpenPGP digital signature
_______________________________________________ devel mailing list devel@ntpsec.org http://lists.ntpsec.org/mailman/listinfo/devel
