Re: ✘UBX-MON-SPAN and antennas

[Gary E. Miller]

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 <gdt@lexort.com> wrote:

> "Gary E. Miller" <gem@rellim.com> 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.

Thanks.

> 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)

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

Yeah.

>  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.


RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
        gem@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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