It’s clearly receiving something, otherwise you wouldn’t have the pretty waterfall in gqrx and sdr#. So this test you are proposing is gonna work just fine, but it’s not helpful in this case.
My guess is that something in the analog frontend of the unit is shot. This results in basically zero actual signal coming in.
Disconnect SMA antenna cable connector from dongle, and insert a 7 cm piece of wire in the center hole of the SMA-Female of Flight Stick (keeping the stick vertical so that the wire is also vertical). Check if you receive any signal with this temporary antenna.
Thin steel tie wire, or one of multiple wires of scrap netwok cable will do the job
Yeah, good call. Maybe the antenna cable is shorted.
PS: Small paperclip works too.
Good idea, as paper clip is very handy, but only small paper clip. The hole of SMA-Female is very fine, and only a thin dia wire of small paper clip can be inserted in it.
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Go to sleep! 
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Has anyone added -10 to the testing for raspberry pi3 and dump1090-fa ??
Are you asking about the gain script?
It’s really a rather random thing to use.
I’d recommend installing graphs and just changing the gain every day manually.
GitHub - wiedehopf/graphs1090: Graphs for readsb / dump1090-fa / dump1090 (based on dump1090-tools by mutability)
A very good starting point is usually 5% messages >-3dB
awk "$(cat /run/dump1090*/stats.json| grep total | sed 's/.*accepted":\[\([0-9]*\).*strong_signals":\([0-9]*\).*/BEGIN {printf "\\nPercentage of strong messages: %.3f \\n" , \2 * 100 \/ \1}/')"
After that any changes to reception are most likely only noticeable over multiple days or comparing to a second station.
Also see this thread where the above command is explained a bit:
Thoughts on optimizing gain - #2 by wiedehopf
Thank you.
I have the graphs1090 install and I’m reading through the optimizing gain thread.
I’ll move over to that thread for question, but at -10 I’m at .030%
seem to be not that busy in your area, you’re far away from traffic or your environment is rough.
I just ran the script with -10 as option with the result below. It’s just a snapshot to get an idea initially. for accuracy i recommend the suggestion of @wiedehopf
With a setting of -10 i have up to 25% messages > -3dBFS
test 1 of 5
gain= -10 messages= 26776 positions= 1148 planes= 89
gain= 49.6 messages= 29137 positions= 1302 planes= 88
gain= 48.0 messages= 28762 positions= 1280 planes= 86
gain= 44.5 messages= 28380 positions= 1227 planes= 84
gain= 42.1 messages= 27719 positions= 1249 planes= 79
gain= 40.2 messages= 28135 positions= 1242 planes= 85
gain= 36.4 messages= 26656 positions= 1174 planes= 86
gain= 32.8 messages= 25229 positions= 1137 planes= 78
gain= 29.7 messages= 25183 positions= 1127 planes= 75
test 2 of 5
gain= -10 messages= 25542 positions= 1080 planes= 94
gain= 49.6 messages= 28507 positions= 1235 planes= 89
gain= 48.0 messages= 28498 positions= 1233 planes= 86
gain= 44.5 messages= 28498 positions= 1262 planes= 79
gain= 42.1 messages= 28014 positions= 1234 planes= 81
gain= 40.2 messages= 27265 positions= 1195 planes= 84
gain= 36.4 messages= 24811 positions= 1021 planes= 77
gain= 32.8 messages= 25387 positions= 1071 planes= 71
gain= 29.7 messages= 24133 positions= 1054 planes= 77
test 3 of 5
gain= -10 messages= 27038 positions= 1175 planes= 88
gain= 49.6 messages= 28498 positions= 1235 planes= 90
gain= 48.0 messages= 28534 positions= 1251 planes= 90
gain= 44.5 messages= 28192 positions= 1313 planes= 93
gain= 42.1 messages= 27914 positions= 1285 planes= 97
gain= 40.2 messages= 27890 positions= 1230 planes= 98
gain= 36.4 messages= 26291 positions= 1220 planes= 88
gain= 32.8 messages= 25806 positions= 1136 planes= 83
gain= 29.7 messages= 22316 positions= 1027 planes= 82
test 4 of 5
gain= -10 messages= 25939 positions= 1128 planes= 104
gain= 49.6 messages= 28279 positions= 1259 planes= 98
gain= 48.0 messages= 28529 positions= 1276 planes= 97
gain= 44.5 messages= 28024 positions= 1242 planes= 96
gain= 42.1 messages= 28043 positions= 1284 planes= 93
gain= 40.2 messages= 28322 positions= 1299 planes= 93
gain= 36.4 messages= 27573 positions= 1291 planes= 87
gain= 32.8 messages= 26231 positions= 1271 planes= 83
gain= 29.7 messages= 25490 positions= 1194 planes= 82
test 5 of 5
gain= -10 messages= 26727 positions= 1209 planes= 94
gain= 49.6 messages= 30310 positions= 1358 planes= 96
gain= 48.0 messages= 29124 positions= 1346 planes= 91
gain= 44.5 messages= 28749 positions= 1380 planes= 90
gain= 42.1 messages= 28786 positions= 1370 planes= 94
gain= 40.2 messages= 29306 positions= 1408 planes= 91
gain= 36.4 messages= 28111 positions= 1387 planes= 83
gain= 32.8 messages= 28797 positions= 1340 planes= 83
gain= 29.7 messages= 27201 positions= 1301 planes= 85
===Totals===
Gain, Messages, Positions, Aircraft
-10 132022 5740 205
49.6 144731 6389 204
48.0 143447 6386 197
44.5 141843 6424 196
42.1 140476 6422 201
40.2 140918 6374 199
36.4 133442 6093 192
32.8 131450 5955 185
29.7 124323 5703 181Yeah, I’ve left the gain script behind and now using the
awk “$(cat /run/dump1090*/stats.json| grep total | sed ‘s/.accepted":[([0-9]).strong_signals":([0-9]).*/BEGIN {printf “\nPercentage of strong messages: %.3f \n” , \2 * 100 / \1}/’)”
command to check message levels. I’ve got both my feeds around 5% now.
Hi all
Just wondering if anyone could tell me how to improve my positions after looking at stat pics
thanks
i am 90% running currently
I don’t think you will find much improvement in small tweaks. Your stats look how I’d expect for your location and the traffic level. The airspy is running with gain at 17, so you have sufficient gain in your antenna/lna to avoid it running at maximum where the noise floor is a bit higher.
Maybe you would see gains from increased antenna height, lower loss feed line, higher quality LNA etc, but I suspect that they would be quite small in comparison to the effort/cost involved in making them.
What you are showing in stats are way better than mine.
Thanks for that, i thought so
i have 20’mast on apex so at my limit
but the fa antenna has a rtl lna in loft - mini circuits splitter
then airspy R2 on to pi4
and 2nd pi4 with airspy mini
so im getting very good signals already even though split
no filters only rtl lna so happy with what i have
im not able to understand the noise levels but there must be some
maybe a cavity filter on the mast
900’s are active around me
Well listening to forums reading alot in forums
taking it all in fiddling on a 2nd setup
squeezing all i can to get that perfect pi4 running
i take it all in most of the time i get it right but i slip some times then i ask for help
its great fun
Radio in general is a great hobby to have. I have a a second Pi4 with adsb-read set up not providing external data just to experiment with antennas.
Probably the most effective change would be to mount the LNA directly under the antenna - that would have the biggest impact on overall system noise since it puts the longest coax section after the amplification and filtering. Realistically though I would not expect huge gains considering your current results - you are already getting nice performance, and although you might see the change in noise/rssi graphs, it wouldn’t necessarily translate to more aircraft or messages received.
I guess it depends how easily you can get access to the top of your mast - if it’s easy, then it’s probably worth trying, but if it’s a hassle then I’d probably leave it as it is until such time as I had to do work on the antenna/mast anyway.
my main setup is pi4 with readsbe
2nd pi4 airspy_adsb
3rd is a 360radar mode A server only
and a very powerful pc for testing on
dont get me on antenna’s ive tried loads
few coco’s was fun i think 8 segments is best keep lobes down
Thanks for reply
i was going to put cavity up top
i have a join in loft to living room where rtl lna is
sooo cav up top and lna in loft
or lna up top cavity in loft
its my aerial man comes £70 + each time so i don’t call him often
just a last note output is same with splitter 1 into 2 as without splitter
