Piaware 1090 & 978 on Pi 3B+

[jpurpora]

I recently “upgraded” from two separate Pi 3B+ devices on Raspberry Pi OS to a single Pi 3B+ using v 4.0 of the PiAware SD card install. I am using the FlightAware blue and orange SDR sticks. I followed the procedure for applying serial numbers to the receivers and modified the piaware-config.

All appears to be working but I am getting considerably less activity. For example I averaged about 400K reports per day with the two Pi setup but now I am only getting about 90K reports. This is over a 75% reduction in reports and I can’t figure out why.

On possible concern is CPU utilization. When I run the “top” command I am showing dump978 using ~48% CPU and dump1090 using about ~31%. Total CPU usage is around 80%, this is higher than I would have expect but I think it should still be OK.

Others have mentioned issues related to power but I have an inline meter for testing and I am supplying a clean 5.15v and 1.3A. I don’t think that is an issue.

I have a heat sync on the system and it is running steady at 44C so I don’t think it is heat.

I am out of things to check and could use any suggestions.

Thanks in advance.

[dongerrard204]

Assuming same antenna and coax is used for 1090mhz system, what gain setting was used on original install vs the gain settings for new/current install?

[abcd567]

@dongerrard204

what gain setting was used on original install vs the gain settings for new/current install?

@jpurpora

To check/set gain on Piaware SD card image :

@abcd567

10 - Adjusting the gain of dongle

Default values are:
The 1090 Mhz dongle is set to gain -10
The 978 Mhz dongle is set to gain 49

To check current gain setting:

• For 1090 Mhz dongle
  piaware-config --show rtlsdr-gain
• For 978 Mhz dongle
  piaware-config --show uat-sdr-gain

To adjust / change gain

• For 1090 Mhz dongle: sudo piaware-config rtlsdr-gain xx
sudo systemctl restart piaware
sudo systemctl restart dump1090-fa
• For 978 Mhz dongle: sudo piaware-config uat-sdr-gain xx
sudo systemctl restart piaware
sudo systemctl restart dump978-fa

NOTE: In above commands, replace xx by the value of gain you want to set

[jpurpora]

On the Piaware SD card install (currently running) both are set to auto gain control using the “max” option.

Looking at both the previous standalone configs under the /etc/piaware.conf files there was not a gain setting applied. I assume that would be whatever the defaults were when the dump1090/dump978 packages were installed.

For testing purposes I manually applied the above noted defaults of -10 and 49.

[wiedehopf]

@jpurpora

On possible concern is CPU utilization. When I run the “top” command I am showing dump978 using ~48% CPU and dump1090 using about ~31%. Total CPU usage is around 80%, this is higher than I would have expect but I think it should still be OK.

That’s percentage relative to one core, so you have 3 of the 4 cores basically not doing anything.
If it added up to 400% it would be fully utilized.

Those numbers are fairly typical.

@jpurpora

Others have mentioned issues related to power but I have an inline meter for testing and I am supplying a clean 5.15v and 1.3A. I don’t think that is an issue.

Have you checked what the SDRs are getting because that’s the relevant part really.
(extensions are notorious for causing unreasonable voltage drop)

[wiedehopf]

@jpurpora

All appears to be working but I am getting considerably less activity. For example I averaged about 400K reports per day with the two Pi setup but now I am only getting about 90K reports. This is over a 75% reduction in reports and I can’t figure out why.

My best guess is you looked at the current day that wasn’t yet over …

[jpurpora]

You are correct. I forgot the daily numbers are in UTC not local time zone. At his point the numbers are closer. I am going to let it run till this weekend before making any adjustment so I can get good data.

With 978 specifically I don’t know yet if I am getting less reports per day but what I am sure of is the web interfaces appears much lower. For example when I had the dedicated 978 Pi I would see minimum 25 aircraft plotted but typically over 100 as I am in range of two major airports. As of this writing I show zero 978 reports and when I do get them they appear to fall off the web map very quickly.

[medic776]

I had noticed the same when I added the second dongle for 978 using a splitter and same antenna. I went and made a second antenna for each dongle and that has helped get back to my original results with a single dongle on 1090.

[foxhunter]

@jpurpora

On possible concern is CPU utilization. When I run the “top” command I am showing dump978 using ~48% CPU and dump1090 using about ~31%. Total CPU usage is around 80%, this is higher than I would have expect but I think it should still be OK.

you can use the commant htop instead of top
This delivers you a small chart at the top showing you the utilization per core.
It also has a filtering option where you can show only what you’re looking for.

That’s mine, filtered on “dump1090”.
It’s a Raspberry 4, but not only for dump1090, it operates also as a Weather-Server and a local VirtualRadar Server instance

I was running my feeder on a 3B for six months without issues and lot of traffic (up to 150 aircraft the same time(

[jpurpora]

After explicitly setting auto gain and taking into consideration the daily totals are based on UTC things are working well.

At the time of this post I have 132 aircraft on 1090 and 141 on 978. I saw a new daily high at 591K reports. I will say it is working well.

I will also note CPU usage on the Pi 3B+ averages 20% across all 4 cores with a peak core usage of 50%.

Thanks to everyone that provided assistance.