What i said:
I will run a test setup with two antennas side by side over the weekend.
What is the default -e value i.e. if you don’t include it in the Options list?
Thanks
Some Aircraft are showing “0” in the RSSI column or something above -1.0
Is this simply not measureable?
Normal.
Not only goes to 10, but 11!
Check the signal graph … adjust the gain so the weakest signal is -30 or -35 …
rtl-sdr RSSI readings compress extremely around -1.4 as well, so you could call that not measurable as well.
The RSSI is calculated a bit differently so it goes to -0 instead of maxing out at around -1.2
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It uses a different RSSI metric from the RTL-SDR. You could probably lower the gain a little.
I think I may need to reduce my gain too.
Tried already lower gain values, it only impacts the message rate. No other impact.
Running with gain 21 deliver the best results
With the airspy, there are also no messages > -3dBFS, correct?
Accidental pop culture reference?
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Not very accidental at all …
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I can do that, but then the message rate significantly drops.
This is the graph of the last hours. The left iart is the FA stick, the right one the Airspy.
You’re imagining it 
Then make it -25 … whatever
You can go lower gain for sure though.
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Hold on, are we talking about the gain setting in airspy config or readsb config?
I am confused, maybe it’s the tme of day why… 
readsb isn’t talking to an SDR …
so it can’t do gain.
And i’m talking about changing the gain so that RSSI has certain values.
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That makes totally sense…
Time to go to bed, will play with it tomorrow.
Thanks for the valuable suggestions
At the suggestion of @caius I dropped my gain down another point about six weeks ago and although it’s difficult to measure, I think my message rate and rate/aircraft may have increased fractionally.
I’m now running my gain at 12 and if you look at my graphs here and select the three month view, you can clearly see when I reduced the gain as the ADSB signal drops (around week 16).
Even with the weakest signals now being down at below -42, it certainly hasn’t reduced my range at all. It’s just that further signals are weaker.
It does have a much better dynamic range so probably not.
Maybe try -e 9 if you haven’t changed it yet.
The ADC dynamic range is so much better, 10.4 bits real accuracy versus about 7.5 on the “normal” R820T chip… that’s why measurements don’t matter that much.
Last year while testing Airspy over the first month, the sweet spot for positions, aircraft, and range seemed to land with Mean Median signal level around 15.5 to 16.5 for my station in the trees. This mean median goes down below 18 when my map is dominated by low flying GA aircraft on sunny days and closer to 15db on rainy days with mostly high flying commercial aircraft on the map.
Every station is different and a few db up or down doesn’t seem to change much with Airspy stats. Just sharing this example since it is what gave me the best results. I’ve also seen roughly similar graphs from other stations with way more impressive stats than mine!
Time to go up, continue playing around with it
Looks like the traffic is not that high here as i can really do somthing with the gain.
Whatever setting i am using between 1 and 21 (values for Airspy) i am always coming back to 21. All other values are reducing the message rate.
Tried 20 MHz and -e 9, but it doesn’t give me any significantly better values.
So i will wait until the traffic is inreasing testing the impact of different settings again.
Maybe it is what you said with “every station is different” that mine does not improve on different settings.
I think a gain of 21 is probably too high unless you have no LNA or some pretty unique situation like limited antenna. Airspy is pretty robust translating the -0db messages, but I’d still recommend letting a lower gain bake for at least half a day before passing judgement. Going from 21 to 19 equals -6db gain.
Even at gain=19 with the Uputronics my peak signal line stays flat at -0db during peak hours.
I’m at gain=19 with Uputronics testing currently (a +13db~ LNA). Before this I had RTL-SDR with gain=14 (a + ~27db LNA). Trying 20 MHz last year did nothing for me. I wouldn’t go there until you have the basics at 12 MHz verified.
For reference:
sudo nano /etc/default/airspy_adsb
GAIN=19
OPTIONS= -v -f 1 -e 10.8 -b -t 180
SAMPLE_RATE=12
#don't change:
G=-g
M=-m
#network settings
NET= -l 29999:beast -l 47806:asavr -c localhost:30004:beast
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Values on gain 21
Values after setting gain to 19 and -e 10.8
No significant change, will keep it for a while. The two more aircraft just appeared on the map after the change coming in range
Number of Aircraft with “0.0” in RSSI is lower
Maybe it is more efficient on higher traffic.
The -e switch only increased the CPU usage to 80% for Decoder.
Any long term damage potentially? I do not have additional cooling for the stick so far.
Or does the -e switch only impact the software?
-b is not enabled as the Uputronic is getting power from RPi USB
EDIT:
By the way: Happy anniversary to me 
