FlightAware Discussions

Piaware 1090 & 978 on Pi 3B+

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.

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?

@jpurpora

To check/set gain on Piaware SD card image :

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.

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.

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

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

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.

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.

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(

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.