Finding the proper Gain for 1090 and 978

[melissajoduff]

I need help finding the proper gain for my dongles.

I saw in previous posts that ( -10 gain ) is like a default for the orange dongle for 1090
and ( 49 gain ) for 978 for the orange dongle. True ???

What about a proper gain setting for the blue dongle for 1090 ???

Is there an article that shows how to tweak the gain, or programs to find the proper gain.

Thanks in advance…

Melissa

[chrislfa]

I’m not sure on the 978 dongles since I’m in the UK and it’s not used here. For the 1090 dongles, I wrote this post which sums up the findings from various people and my own experience too. It should help you to home in on the right level of gain for your setup. It uses the graphs1090 addon to visualise the results. You will likely find other ways to improve numbers too, such as antenna placement, the antenna itself, perhaps a filter or preamp. There are various posts around the forums exploring those.

[foxhunter]

There are meanwhile a couple of threads about setting gain. Simply search and read

this one for example:

Thoughts on optimizing gain

The topic of gain comes up often enough and unlike some i don’t like the gain optimization script. Aircraft fading in and out of view make short term number gathering not that useful. The metric i like most for optimizing gain is the percentage of what dump1090 calls “strong_signals”. Those “strong_signals” are messages that get close to getting clipped. If you don’t care about some background you can scroll down to the next post for the HOWTO This is a clipped signal, the wa…

[Frazpo]

Could someone give some advice on interpreting graphs1090?
Ill post a pics. I lowered gain and I seem to have improved closer traffic but the graphs indicate change and really unsure what it means. For instance on the message graph, as you can see I lowered the red area which is 1 message tracks. On the other,It seems I put the range in the more negative DB’s. Are these graphs indicating a good move in reducing gain??