After 8 hours of testing, I can see that the RTL-SDR LNA has seen more positions and aircraft than the Uptronics LNA, but it (the Uptronics LNA) sees planes further away (+ 20NM approx).
Next test tomorrow with the addition of the Bias Tee !
Looking at your stats, both devices actually seem very similar.
Weather changes range quite a bit and day of the week changes traffic significantly.
Testing each a week or so might give you a better picture.
But i’m curious, why aren’t you switching to the Pi4, 20 MHz does make quite a difference for stations with so many planes in view.
I haven’t switched beceause Amazon was late to send me a package containing the Pi4 case with fan ;+))
Normally it’s coming tomorrow, so we’ll test it sometime in the next week !
Oh just hang it in the garage, it’ll be fine in free air!
But i understand waiting for the case 
Finally I received the case for my Pi4 !
So now my installation is upgraded 
Now i’m using Raspberry Pi4 with 3.7.2 Flightaware on Raspbian Buster (starting from a fresh image).
AirSpy Mini with a Bias-Tee
And the Mlat is configured to 20Mhz !
The Pi4 without the case is at 60°C and 40°C with the new case 
For the moment, I do not have any difference (number of planes seen and messages received) compared to before !
I just have to configure FR24 again on the new Pi4…
If you still have the old pi running, you can scp over the old graph data.
On both pis, stop collectd:
sudo systemctl stop collectd
then on the new pi:
sudo scp -r pi@192.168.2.123:/var/lib/collectd/rrd/localhost /var/lib/collectd/rrd/
IP of the old pi needs to be modified:
192.168.2.123
To restart data collection:
sudo systemctl restart collectd
Also with 20 MHz you might want to step up the gain one notch.
Positions per second have increased from 80 to 100.
Also 1800 messages per second was only peak before but now it might happen more often.
Yes good idea, but I have already reformat the old SD card for another project ; +)
Ok I just passed it from 14 to 15 !
Ah yes, i haven’t seen that !
Which one are you using?
I was looking at the /var/log/piaware.log log and found this :
piaware[535]: mlat-client(3448): fa-mlat-client 0.2.10 starting up
piaware[535]: mlat-client(3448): Using UDP transport to 70.42.6.197 port 5429
piaware[535]: mlat-client(3448): Listening for Beast-format results connection on port 30105
piaware[535]: mlat-client(3448): Listening for Extended Basestation-format results connection on port 30106
piaware[535]: mlat-client(3448): Input connected to localhost:30005
piaware[535]: mlat-client(3448): Input format changed to BEAST, 12MHz clock
piaware[535]: mlat-client(3448): Beast-format results connection with ::1:30104: connection established
piaware[535]: mlat-client(3448): Receiver status: connected
piaware[535]: mlat-client(3448): Server status: synchronized with 97 nearby receivers
piaware[535]: mlat-client(3448): Receiver: 1718.2 msg/s received 358.6 msg/s processed (21%)
piaware[535]: mlat-client(3448): Server: 0.2 kB/s from server 0.1kB/s TCP to server 3.0kB/s UDP to server
piaware[535]: mlat-client(3448): Results: 107.3 positions/minute
piaware[535]: mlat-client(3448): Aircraft: 37 of 51 Mode S, 75 of 178 ADS-B used
That speaks of a clock at 12Mhz, whereas I should be in 20Mhz !
Did I miss something ?
Beast protocol is 12 MHz so it’s compatible.
The 20 MHz is mainly the sample rate, so it improves reception.
(also the mlat frequency for the airspy mlat server i believe, but that’s kinda besides the point)
Ok so it’s normal, thank for your help !
For information i have (for test) switched back from the RTL-SDR LNA to the Uptronic model.
I found that with RTL-SDR’s LNA my numbers of planes seen a day had decreased in recent weeks.
So I test again with the model from Uptronics, having set the gain on 19 and always in 20Mhz.
It’s called fall, or maybe more eloquently autumn.
2 Likes
I thought well of this change of season, but in view of the planings of the flights of CDG and ORY, it does not match, so I test ;+)
This morning I gave myself a test, certainly not very sientific !
I swapped the Uptronics LNA with RTL-SDR LNA, and then went back to Uptronics LNA, so it gives :
1 → Uptronics LNA
2 → RTL-SDR LNA
3 → Uptronics LNA
When the RTL-SDR LNA is connected the values go down.
Tonight My AirSpy Mini stopped working !
Nothing in the log exept this in /var/log/syslog :
Oct 13 00:33:18 ads-b airspy_adsb[330]: Decoding stopped
Oct 13 00:33:18 ads-b airspy_adsb[330]: Push client disconnected from localhost:30004 (beast)
Someone already had this problem ?
Edit: Of course i have seen this before:
Oct 11 15:36:28 pi airspy_adsb[298]: Caught signal 15
Oct 11 15:36:28 pi airspy_adsb[298]: Decoding stopped
Oct 11 15:36:28 pi airspy_adsb[298]: Push client disconnected from localhost:30004 (beast)
Oct 11 15:36:28 pi systemd[1]: Stopping Airspy ADS-B receiver...
Oct 11 15:36:28 pi systemd[1]: airspy_adsb.service: Succeeded.
Oct 11 15:36:28 pi systemd[1]: Stopped Airspy ADS-B receiver.
That’s just the service being stopped.
This log is usually more comfortable to navigate:
sudo journalctl -eu airspy_adsb