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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. RGDS GARY --------------------------------------------------------------------------- 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
mux2.png
Description: PNG image
mux4.png
Description: PNG image
tee.png
Description: PNG image
pgplulfcNoWrH.pgp
Description: OpenPGP digital signature
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