Here’s the result. Shall i be concerned about the first two lines?
And what does the other lines mean?
cat: /var/tmp/dump1090-fa-autogain/strong: Datei oder Verzeichnis nicht gefunden
cat: /var/tmp/dump1090-fa-autogain/total: Datei oder Verzeichnis nicht gefunden
Set rtlsdr-gain to 49.6 in /boot/piaware-config.txt:60
Decreasing gain to 49.6 (17.265% messages >-3dB)
No, it’s normal for the first run.
Well it’s reducing the gain to 49.6 because the percentage is larger than 3%.
“messages >-3dB” are messages that are nearly too strong for the receiver to be received.
Thanks for your support!
What does it mean or better: what can i expect now?
Just for getting it confirmed that it improved something (or not)
Maybe you receive a few messages that were too strong before to be received at all.
Small aircraft flying really close or maybe a rescue helicopter flying by might show a continuous track on the map instead of vanishing if they come too close.
Your really have to understand a bit about signals to understand the benefits of correct gain.
So it’s hard to explain.
Look at the graphs and check if anything changes 
Imagine you can’t hear sounds that are too loud or too quiet.
Then you want to adjust the volume (gain), so all the planes are neither too loud nor too quiet.
Got it!
Meanwhile the graphs are updated and indeed there were changes.
The signal level and the amount of messages > 3dB went both down.
Is the lower signal level ok? The range also is slightly reduced or is this still the normal variation?
Most likely normal variation.
Range back to normal.
Again thanks for your scripts and the support. Very useful, especially for me as beginner
A colleague has set up PIAware yesterday on his device, but he’s living in a heavy environment with very low range and signal, using a normal DVB-T stick.
Would it help to run the script? Or is it only if “too strong”?
Only useful for amplified sticks unless you literally live 1km from the airport and have a good outdoor antenna.
But it doesn’t hurt, it would just leave the gain at maximum.
got it, thanks
In this case he can leave the system as it is and better find a new home 
This setting should be banned (max or -10).
Work with a maximum of 49.6, and down from there.
Good morning,
tonight the script was setting the gain to the “forbidden” value -10:
Jul 24 02:40:58 piaware systemd[1]: Started autogain for dump1090-fa.
Jul 24 02:40:58 piaware dump1090-fa-autogain[28137]: Set rtlsdr-gain to -10 in /boot/piaware-config.txt:60
Jul 24 02:40:59 piaware dump1090-fa-autogain[28137]: Increasing gain to -10 (0.950% messages >-3dB)
That increases the message ratio > 3dB again to approx 10% now that the sky gets busier
Wouldn’t this be contraproductive?
I simply ran the script again and now the value changed to 49.6
Well with that gain step it’s complicated because one step is a rather large change.
The script logic isn’t too smart and can result in toggling between two gains.
Most likely in that case both values work fine so it’s not a problem.
If you notice an actual performance difference between the values or a happier with a particular value you can always set gain manually and remove the script.
Wow you’re also that early busy
Thanks for your suggestion, i will monitor it for a few days and let you know.
Not sure if this is just by chance, but i get the feeling that the difference between “Total Aircraft” and “With Position” is smaller after the gain adjustment.
Why not remove the -10 from this line?
https://github.com/wiedehopf/adsb-wiki/blob/master/dump1090-fa-autogain.sh#L94
Because it provides 6dB more gain than 49.6.
This is a peculiarity of the rtl-sdr library.
And in my experience a 6dB reduction in SNR.
Not really.
Without any amplification and simple ground plane antenna in the attic, it provides quite a bit of extra range.
At least that’s the case when i tried with the rtl-sdr v3.
