Very weak singnal from NOAA with QFH anthenna

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estario
Posts: 7
Joined: Sun Nov 25, 2018 5:43 am

Re: Very weak singnal from NOAA with QFH anthenna

Post by estario » Thu Nov 29, 2018 7:35 pm

This is my antenna:
Image
This is the wiring. I know it looks messy, but I just want it to work once. If it does I will make a final precise model.
Image
This is the SMA adapter.
Image

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Evap1
Posts: 17
Joined: Sun Nov 25, 2018 2:54 pm

Re: Very weak singnal from NOAA with QFH anthenna

Post by Evap1 » Fri Nov 30, 2018 12:28 pm

Hi Estario,
Please see Picture.
Remove any potential short circuits and you should be good to go!
Evap1
Estario Ant1b.png
Estario Ant1b.png (258.61 KiB) Viewed 1436 times

estario
Posts: 7
Joined: Sun Nov 25, 2018 5:43 am

Re: Very weak singnal from NOAA with QFH anthenna

Post by estario » Tue Dec 04, 2018 7:09 am

Ok. I resoldered everything, peeling back the insulation of the cables and making sure there are no shorts. The signal is a bit better, but still far from good. Best SNR 24 with the satellite directly over my head.
nexttrynoaa.png
nexttrynoaa.png (546.72 KiB) Viewed 258 times

gmenga
Posts: 5
Joined: Tue Dec 04, 2018 8:28 am

Re: Very weak singnal from NOAA with QFH anthenna

Post by gmenga » Tue Dec 04, 2018 2:42 pm

I'm surprised. I once went on the web, found the instructions and the measures, and I built a similar antenna to track satellites with just a iron wire to hang the wash and it worked perfectly from the start.
Let try to substitute the coaxial cable with just a wire, and pay attention to the right connections
Giuseppe

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Evap1
Posts: 17
Joined: Sun Nov 25, 2018 2:54 pm

Re: Very weak singnal from NOAA with QFH anthenna

Post by Evap1 » Tue Dec 04, 2018 9:35 pm

Hi Estario,
Did some pictures for you from this evening's Noaa-18 Pass.
(Noise in your Waterfall).
You seem to have the gain too high and this will introduce noise and also
pull in other close-by signals.

Try to set the FFT screen to 50 or 60 and adjust the gain to suit.
The key to this is SNR (Signal to Noise Ratio).

If you are getting Horizon to Horizon e.g. 14 to 15 minutes for an overhead pass you are doing OK.
You may be getting de-sensing from strong FM Transmitters close to you.
Try an FM blocking Filter in the Co-ax line before the Dongle.
Problems this end are with Pagers, see picture.
Test for you this evening with just a Quarter-wave vertical, V3 Dongle + RTL FM Blocking Filter.
Evap1
noaaLos.png
noaaLos.png (1.46 MiB) Viewed 199 times
noaa18 at 52 degrees.png
noaa18 at 52 degrees.png (1.49 MiB) Viewed 199 times
Noaa 18+Pager.png
Noaa 18+Pager.png (575.51 KiB) Viewed 199 times

estario
Posts: 7
Joined: Sun Nov 25, 2018 5:43 am

Re: Very weak singnal from NOAA with QFH anthenna

Post by estario » Thu Dec 06, 2018 4:51 pm

Hi,
Thank you guys. Your support is great. I am out of home for the next week. Once I am back I will do another attempt.

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