Need help with setting up my GS

SatNOGS
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1

Hello, i recently put up my antenna on my roof, it’s a turnstile cross-dipole 137-152MHz.
I tried listening to NOAA satellites just by putting the RTL-SDR into my computer and i saw a little bit of data come through ( it was a bad pass, but i at least confirmed i got something )
Now when trying to listen via satNOGS, i get nothing.

Here’s an example of what i get:
https://network.satnogs.org/observations/11689282/

Does anyone have any ideas what could be the issues?

Thank you in advance

2

I guess i should’ve provided some more information, i’m using RTL-SDR v4 on a RPI 5
The antenna is mounted on a chimney and i have a cable that runs 5m from the antenna to my RPI, the cable connection works, as stated before.
Antenna

3

I notice a lot of values being reported “null” in your metadata and the one most hitting my eye is:

  • gain-mode: “Overall”,
  • gain: null,
  • antenna: “RX”,
    So, your Overall gain setting appears to be either not set, or set to zero, making it impossible for the RTL-SDR receiving anything further away as 10 meter :wink:
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4

Thank you so much!!!
I changed the gain to 30 just to test about 3 minutes before my next pass and i actually got something.
https://network.satnogs.org/observations/11689718/

Now how could i optimize the best gain value? I read the wiki about it, but it didn’t help me much, is trial and error the best approach?

5

Excellent result for now ! By looking at the image you appear to be somewhere in Italy ? Might even be Greece …

For checking the best gain setting it’s recommended to stop the running satnogs station and start some SDR software like gqrx, sdrpp or, depending on headless system, rtl-tcp server on the satnogs station and some client on another system.

By running sdr rx software you can adjust the gain as high as you barely see the noise lever rise in the waterfall. If you raise the gain with 3 dB and the noise floor raises more as this 3 dB your gain is to high (my general rule…)

Do you have any experience with SDR software ?

6

You’re close, the station is in Slovenia and no, i have no experience with SDR software.

7

On what kind of system are you running the satnogs station ? Something with a desktop environment ?

8

Not really, RPI lite OS, meaning no desktop.

9

You wrote you did put the rtl-sdr in your computer so you must have some SDR software experience ?

10

Oh well i know as much as my friend told me :slight_smile:
I used SDR++, that’s really the only software i have experience with, could i use that to identify the ideal gain?

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11

Yes you can,

Below a table with on the first row SDR++ values when you use a RTL-SDR and the second row is the corresponding SatNOGS (Soapy) gain value.

RTL-SDR gain Values:

  0   1   2   3   4   5   6    7    8    9   10   11   12   13   14   15   16   17   18   19   20   21   22   23   24   25   26   27   28
0.0 0.9 1.4 2.7 3.7 7.7 8.7 12.5 14.4 15.7 16.6 19.7 20.7 22.9 25.4 28.0 29.7 32.8 33.8 36.4 37.2 38.6 40.2 42.1 43.4 43.9 44.5 48.0 49.6
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