[time-nuts] eBay GPS antennas

Bob kb8tq kb8tq at n1k.org
Fri Feb 16 18:50:27 EST 2018


Part of the issue with Glonass is the accuracy of the datum. It *can* be used
for navigation and timing. It’s best to use it stand alone. Survey a location 
that is specific to it’s datum and then lock the module into timing mode. Don’t 
try to run with a GPS survey as your location.

All that said, still not encouraging. 


> On Feb 16, 2018, at 2:49 PM, Gary E. Miller <gem at rellim.com> wrote:
> Yo Bob!
> On Fri, 16 Feb 2018 13:47:24 -0500
> Bob kb8tq <kb8tq at n1k.org> wrote:
>> Reports to date on Glonass have not been encouraging.
> I have been testing position accuracy lately on a self contained u-blox
> 8 with built-in antenna supposedly GLONASS capable.  I write a Python
> script to selectively enable GLONASS and GALILEO over GPS.
> All figures below are rough averages.
> Typically, with one particular GPS, in one particular spot, it gives a
> CEP(50) of 10 feet.
> Enable GLONASS and that worsens to 24 feet.  After about a minute the
> u-blox rejects all the GLONASS, that have good SNR, and the CEP(50)
> drops back to normal.
> Enable GALILEO and CEP(50) improves to 6 feet.  And stays that way.
> So be sure to enable GALILEO in your GPS and disable GLONASS.
> Also note: the passband of GALILEO is technically the same as GPS, but
> has more energy at the edges.  Some GPS antennas cut it a little close
> and hurt GALILEO performance.
> ---------------------------------------------------------------------------
> Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
> 	gem at 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
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