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Re: ✘UBX-MON-SPAN and antennas

From: Gary E. Miller
Subject: Re: ✘UBX-MON-SPAN and antennas
Date: Tue, 22 Feb 2022 17:08:53 -0800

Yo Greg!

Uh, oh.  Due to a brain fart, the antenna ;abeled ANN-BM0 is actually
another generic GPS+GLONASS.  I'll quickly add the real ANN-MB0 in
a few minutes.

On Tue, 22 Feb 2022 19:42:52 -0500
Greg Troxel <> wrote:

> "Gary E. Miller" <> writes:
> > The UBX-MON-SPAN message is a 256 bucket power spectrum around the
> > frequencies supported by the GNSS receiver.  The M10S is L1 only,
> > and the F9P is L1 and L2.  
> Very cool.


> The graphs seem to be a combination of
>    - power spectrum of what is actually being transmitted
>    - antenna gain as a function of frequency
>    - preamp gain
>    - cable loss

Yup.  Plus the LNA and filters in the receiver.

> It would be interesting to have some reference data for power
> spectrum.

What sort of data are you looking for?  IS-GPS-200M has the data
for the power spectrum you should receive on the earthfrom a GPS sat.

> GPS L5 at 1176 doesn't work well on any of those.

I found the ANN-MB0 worked fine with L5 on a Trimble RES720 (L1/L5).
And the other two not so well.  No way to get this data from a Trimble.
Eventually I'll get a u-blox L5 receiver.

> I know there are now some tri-band antennas (I don't have one):

I a multi-band one coming from China.

> and indeed the normal "dual band" antennas do not support E5a and L5
> and are iffy on E6/B3 and E2.

I used to think so, now I am not so sure.  Now I want data.

> (E2 is near E1, and I don't understand
> how it is used):

E1 is Galileo, E2 is BeiDou (1561.098MHz, 16MHz)

> It looks like all 3 work perfectly fine for GLONASS G1 and G2.  I am
> also surprised about how close they are.


>  I am guessing G3 (sort of like E6) won't work well.

If I could only test...

> Galileo:
> It looks like all 3 don't work very well at E5a (1176.45) but are ok
> at E5b (1207.14).  E6 at 1278.75 is also beyond what works.

Or maybe the receiver SAW filter just cut it out.

Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703  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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