Also seem to be getting narrower range of dBFS values between -6 and -18 on 978 with the orange FA and blue FA filter. This plot had uat-sdr-gain starting 45 and ending at 38 with a systemctl restart dump978-fa at about 1055. Not sure what to expect since RTL-SDR v3 goes from -5 -26. Maybe reduce gain to 30 dB?
@wiedehopf,
I have to agree on using a dongle without an LNA when using an LNA at the antenna. That’s one reason I set the dongle gain reletively low. The receiver for 1090 seems to have terrific signal range with the blue dongle and without an LNA at the antenna with up to 300NM range. I’ll post the chart.
The 978 receiver uses the orange dongle (almost brand new) as noted in @turbodogfl’s message above he has decreased the gain a bit. maybe I’ll try an RTL-SDR-v3 (I do have one) and set the gain reletively high maybe -20 or so and see what happens. I don’t think I have tried this so far.
Note the 7-day 978 graph shows over 20dB down compared to -42 with the 1090 receiver (24h).
???
gain settings for rtl-sdr compatible dongles:
minimum gain setting → 0 … 49.6 -10 ← maximum gain setting
You probably meant adjust gain so that the weakest signal is at -20?
Adjust it so the minimum signal is at -30, that’s more reasonable.
That’s the rtl-sdr v3 gain or the orange flightaware dongle?
They all have the same gain settings.
The extra LNA can’t be adjusted and you need to take that into account independent of the gain.
Think I’ll try the rtl-sdr + Flightaware filter for a week leaving the mast mounted LNA/filter in place and see what I get. Rainy miserable day not much 978 traffic not good for VFR flying so have to wait for nicer weather for signals to show up.
Are you sure you are even changing the gain?
Some people do it wrong and never actually change the gain.
Am trying uat-sdr-gain 26 with orange FA and got dBFS down to -23
piaware-config uat-sdr-gain 26
It says it updated the value
sudo systemctl restart dump978-fa
second putty window running >socat -u tcp4-connect:127.0.0.1:30978,forever,interval=5 STDOUT | uat2text
gets a new shell prompt showing that something happened.
last uat flight visible after changing to 26
The earlier test at 30 had 2 flights showing in skyview, one disappeared after flying into short range - possible overload. so suggested gain might still be lower like 20…
I’m using a rtl-sdr V3 for 978 UAT. Gain is at 49.6. Antenna is inside. FlightAware dual band filter on yesterday, came off this morning, before any visible aircraft. Seemed a little better reception today, but it’s the weekend vs Friday traffic. Have yet to figure out the correct gain setting or whether the filter helps. Using Orange Prostick for 1090. (Of course i’m impatient and want to change the gain everytime i see an aircraft nearby. 
)
Here’s the graphs:
UAT plane went over a while ago so I have some data for the RTL-SDR-v4. Signal range seems to have improved a bit possibly but need more data to know for sure. Using a gain setting of 24 for the RTL-SDR.
UAT graphs look good. rtl-sdr V3 seems to work well with max gain. link to a graph that appears to have good gain adjustments 1-3 dB gap at the top Graphs for dump1090 -- my version with install script - #314 by bive
A nice explanation of how gain adjustment works Daily Log/E-Mail Aircraft Report directly on your RaspberryPi - #120 by david.baker In my case, can tell a UAT might stop registering if flying very close but that doesn’t happen often. Possible gain values ```
gains = “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 max agc”.
With the RTL-SDR v3 and no pre-amp at the receiver end I seem to be getting better signal range now. Some bad VFR weather lately so counts are down on 978.
Dump978 Graphs
right click → copy image
Ctrl-V here in the text box.
You can’t link your local ip 
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Wierd… will try again…
Could set it up to link to my IP, but not likely a good idea.
You copied links to the images, which point to your local IP address.
That works for you, but not for others.
The buttons for “Copy image” and “Copy image link” are adjacent to each other
The new ones work like a charm.
Sadly the signal graph for 978 doesn’t work very well with the interruptions.
I’ve made an experimental change, if you would like to experiment do the following:
Update the graphs:
sudo bash -c "$(wget -q -O - https://raw.githubusercontent.com/wiedehopf/graphs1090/master/install.sh)"
And then change the database format to the new format i just specified (should display a more consistent signal graph for 978)
sudo apt update
sudo apt install -y screen
sudo screen /usr/share/graphs1090/new-format.sh
Don’t expect an immediate change, it will only take effect for newly collected data.
2 Likes
Installing. Will post charts after 24 hours or so.
Thanx!
-G.
That looks best on the signal level graph.
The change in aircraft number is likely just normal fluctuation due to weather etc.
And under no circumstance would i go higher than a gain of say 28.
After changing
ul_range_uat=60
with
sudo nano /etc/default/graphs1090
sudo /usr/share/graphs1090/boot.sh
found How to setup the SDR for maximum and close range? Impossible?