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[gpsd-users] ✘Tee'd Off

From: Gary E. Miller
Subject: [gpsd-users] ✘Tee'd Off
Date: Mon, 15 Oct 2018 15:02:20 -0700

Yo All!

I got a new 4-way SMA splitter.  Time to run a few new tests.

Attached are 3 polarused plots.  Generated this way:

# gpsprof -n 120 -T pngcairo -f polarused | gnuplot > XX.png

Where XX.png is:

mux2.png     2-way splitter, DC block on 1 port.
mux4.png     4-way splitter, DC block on 3 ports.
tee.png      simple tee, DC block on one side of tee.

In all cases the input is a 42dB gain roof top antenna.  So no worries
about initial signal strength.

120 samples is a pretty short sample time.  The GPS needs a minute
to recover from the total signal loss.

The results bounce around between 17 and 18 sats seen.  Average SNR of
around 46.5.  Note when the 18th sat is seen, the average SNR drops.

Pretty much a wash.  My OCD will generally prevent me from using the
simple tee, but if that is all I have handy, I'll use it.

Proving once again that SNR is the important variable.  Signal strength
just needs to be "good enough".

Next I should get some atenuators to play with the signal strength.

Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
        address@hidden  Tel:+1 541 382 8588

            Veritas liberabit vos. -- Quid est veritas?
    "If you can’t measure it, you can’t improve it." - Lord Kelvin

Attachment: mux2.png
Description: PNG image

Attachment: mux4.png
Description: PNG image

Attachment: tee.png
Description: PNG image

Attachment: pgplulfcNoWrH.pgp
Description: OpenPGP digital signature

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