[time-nuts] eBay GPS antennas

Gary E. Miller gem at rellim.com
Fri Feb 16 14:49:53 EST 2018

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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