New Raspberry Pi available - Pi 4

FlightAware ADS-B Flight Tracking
586

Yep, that and the antenna being in my attic.

Antenna <–> filter/amp <–> 50 feet of LMR-400 <–> Airspy

I could put the antenna outside, but i don’t want to add that enhanced attraction for lightning. If I had a remote power setup (solar) I could run wireless between there and the house without an issue. Lack of ambition though. It’s so nice to just walk up to the equipment in my house and work on it.

But I’d venture to say I could put the antenna up at 40 feet (and out in the air) and it would likely make a huge improvement on the number of planes. Oh well. Maybe next year.

587

Ok. I didn’t realize that. That’s good then. Looks like I’ll be in the “safe zone” then for the foreseeable future. I don’t anticipate connecting anything else to it. My old PI3B is doing 978 (with no amp and 770 mhz yagi LOL) right now. I have a dedicated amp / antenna / LMR-400 for it, if I were to ever feel ambitious enough to put it up. The Odroid – well now it’s just some play toy with nothing to do.

Thanks for all of the help!

Mike

588

Hmm i somehow doubt that.
Your reception equipment is that good that you might get the terrain limited range despite the roof :slight_smile:
But if other houses are around you it sure might help.

589

Good point. I consider you my “voice of reasoning” LOL. NW is my worst direction, because of a hill directly behind me. There is no getting around that obstacle.

mike

590

Hello,

I am interested in having a Raspberry Pi controller / tracker - however I am not sure I have the skills to assemble a unit. I am willing to buy the basic parts and send them to a volunteer who can help assemble it. I’m just not techie enough in Pi etc to pull this off. Any ideas on a volunteer who might help?

Thanks
David

591

@mtindor,
I had a GPS/GNSS usb dongle and the airspy plugged into the two ports next to each other on the Adroid XU4. MLAT did not work. I suspect it is related to the GPS/GNSS dongle only working at 11Mb/s. I moved the airspy to the other side(single USB port), also removed the GPS/GNSS dongle and moved the rtl-sdr dongle to the other side, and MLAT started working.

592

That’s interesting. I have an N2. But I imagine the XU4 also has four ports. I figured they would all be part of the same single USB hub, and as such I would have thought it didn’t matter what ports that multiple devices were plugged into – and that you’d still have the issue. That’s certainly food for thought.

In my case, i was only running one USB item on my N2, and that was the Airspy. So there was nothing else on the USB port that should have been causing an issue.

Mike

593

Take a look at PiAware - build your own ADS-B ground station for integration with FlightAware - FlightAware
Assembling a basic piaware receiver is not technically complicated (IKEA furniture is probably worse!), you should be fine.

One gotcha: currently, if following those instructions, make sure you buy a Raspberry Pi model 3B+, not the recently released Pi 4.

1 Like
594

The N2 has some sort of kernel USB problems.

Some older kernel/ image versions apparently work better. (Hardkernel images)

1 Like
595

I concur with @mtindor observations completely. I stood up a new Pi4 with Airspy-R2 last week and jumped it up to 24MSPS. MLAT solid with no issues. CPU increased about 5% on the graphs - overall hitting just shy of 50%. Temp steady at 48-50C at all times. Using a PoE hat with built-in fan. Unit mounted in a box on the roof.

As others have noted, I haven’t seen a significant difference in message rate between 20 and 24MSPS. To be fair, I don’t stress it too much as the airspace in my area is pretty mediocre. On a busy weekday, I’ll see around 170 planes at once producing around 1,200 to 1,300 messages/sec. The system may eek out a few more decodes per plane during this time, but its hard to tell. Overall, I’m very pleased with the Pi4 and Airspy unit.

3 Likes
596

So I just removed the RTL-SDR dongle from my RPI4, leaving only an airspy mini.
MLAT starting working again.

It looks like the RPI4 cannot handle another USB1 or 2 device plugged in when using the airspy.

1 Like
597

Just an observation. With the PI4B and the Airspy running @24 MHz, I had no issues. But I was curious since I didn’t notice a significant increase in anything by going from 20 MHz to 240 MHz. I dropped it back down to 20 MHz today and the message rate is up bout about 100/sec. I switched back and forth over steady five-minute periods, and it really seems like I’m getting a higher message rate at 20 MHz. So I’ll be keeping it there.

m

598

Can you record 10 seconds of traffic at 20 MHz and 24 MHz using airspy_rx?

599

I’ll see what I can do.

mike

600

Is this what you will be looking for?

timeout -s INT 10 airspy_rx -r dump20.bin -t 4 -a 20000000 -f 1090 -g 21 -b 1 -p 1
timeout -s INT 10 airspy_rx -r dump24.bin -t 4 -a 24000000 -f 1090 -g 21 -b 1 -p 1

  • bit packing enabled
  • bias tee enabled (assuming you actually want to see my traffic)

If that’s what you need me to collect, I’ll do that and make it available for download.

Mike

1 Like
601

Interesting. When I got the RPI4 (running Raspian Buster Lite – all up to date) set up, I never bothered to run airspy_rx on it. I just did that now, and apparently this setup isn’t handling 20/24 MHz even with bit packing enabled.

timeout -s INT 10 airspy_rx -r dump20.bin -t 4 -a 20000000 -f 1090 -g 21 -b 1 -p 1
Total time: 9.9551 s
Average speed 18.9478 MSPS Real

timeout -s INT 10 airspy_rx -r dump24.bin -t 4 -a 24000000 -f 1090 -g 21 -b 1 -p 1
Total time: 9.9541 s
Average speed 22.7807 MSPS Real

Disregard this. This is only problematic when dumping to sdcard. If I test via “-r /dev/null” the speeds are normal.

602

Yeah somewhere in the “new decoder” thread i have posted some code to dump to a ram disk.

1 Like
603

Thanks, I’ll look for it. Otherwise, any dumps I make available to Youseff are going to less than optimal :slight_smile:

I wonder if my Odroid N2 would have done that, with its eMMC. It’s disk performance was way faster.

604

Found it:

sudo mkdir /tmp/ramdisk
sudo mount -t tmpfs -o size=700m tmpfs /tmp/ramdisk
sudo systemctl stop airspy_adsb
timeout -s INT 14 airspy_rx -r /tmp/ramdisk/dump.bin -t 4 -a 24000000 -f 1090 -g 18
mv /tmp/ramdisk/dump.bin /tmp
gzip -1 /tmp/dump.bin

Then upload /tmp/dump.bin.gz somewhere.

After uploading or moving it to the sd-card and freeing up the memory you can do the other sample rate.
Two files won’t fit.

Edit: caius is correct :slight_smile:

1 Like
605

You might need to copy the file elsewhere to gzip it - I found that it would run out of space and fail if I tried to do it in place.