FlightAware Discussions

HOWTO: Airspy mini and Airspy R2: Piaware / dump1090-fa configuration

Do you think it may work with one Airspy (for 1090, say) and one dongle (for 978, say)

Yeah that’s what i was saying i my last post.

Not sure how congested USB would get though.
Could be fine could be not fine.

It works with -m20 which is almost double the amount of USB bandwidth compared to -m12.

So using a rtl-sdr in addition should work.

The CPU load bottleneck is normally on one CPU core, even with -m20 the RPi 3B+ is mostly using one core and the other 3 are free.
So dump978-fa using half or so of another core should be fine.

It’s gonna produce more heat but that’s always something to look out for when running the RPi under load.

Thank you for the help Wiedehopf. I do not understand how to select the AirSpy R2 as the 978 dongle during concurrent 978 and 1090; am I to use R2’s serial number as the identifier, al la the serialized RTL-SDRs?

I’m back to 3.6.3, on the 3-, with R2 generating reports thanks to your automatic script.

I thought you would want the airspy to do 1090 MHz.
That will work with the script as airspy_adsb takes care of 1090 MHz.
airspy_adsb can’t decode UAT.

dump978-fa using the airspy soapysdr driver will not work on a Raspberry Pi, it uses a lot of CPU even on a proper not too old laptop. (70% of a core, i’ve tested it)

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Rather than restart the pi after adjusting the gain in /etc/default/airspy_adsb, which service should I restart please?

sudo systemctl restart airspy_adsb dump1090-fa

With restarting dump1090-fa as well you don’t get MLAT errors that can happen otherwise.

Changing config and restarting for config reasons is described here:


Thanks, I knew I’d seen that somewhere :slight_smile:

There is only one word to describe this.


I’m very well sited, not far from this location and I never see more than 1,600 messages/second. I don’t know how much of this increase is due to the Airspy and how much is due to the difference between a Pi 3B and a Pi 3B+ but this is seriously impressive. This is hovering around 3,700 to 3,900 message/second with the occasional jump up over 4,000. It’s seeing around 40-50 more aircraft than my own receiver with a far greater number being further out.

Gain is set to 18 with the weakest signal showing at around -23 and the strongest at 0.


hello keithma, can you advise re the 3B+

  1. are you using wifi or ethernet?
  2. are you using turbo mode?
  3. what other changes have you made to the 3B+

sorry if you’ve covered this in other posts, i couldn’t find

  1. Ethernet.
  2. No, it’s straight out of the box.
  3. Nothing. It’s a plain vanilla 3B+ with a heatsink on the CPU and a small fan.

It’s 12 MHz sample rate. No chance with the RPi 3B+ to go 20 MHz sample rate with that many planes and messages with the current software provided.

I’m curious, do you have my graphs installed? Would be interested in the CPU consumption.
Could you also check for lost samples:
journalctl -eu airspy_adsb

One part is the LNA, the other part is the Airspy.
(And of course a good antenna being installed close to the LNA)

The RPi version really shouldn’t affect reception.

Great location and setup!
May i ask for the link to the FA stats of the receiver?

I’ve been checking for lost samples and there are none at all - I even ran at 20MHz samples for a few minutes and didn’t see any lost samples either but I’ve put it back to 12 for the moment. We’re using the Uputronics LNA with the ceramic filter.

Not sure which CPU stats you want so here are both the graphs.

This actually went live yesterday but we had a fault with the aerial so it’s been swapped today. You can see exactly when that was done just a couple of hours ago.

/edit - Updated with the six hour CPU charts

FA stats page is here.

The blue one. That’s airspy and it’s related to running on one core.
No danger at all losing samples with that CPU load, only get’s critical around 80%-90% or so.

Do you know what the problem was?

That seems to be a very solid device.
I mean it better is at that price, but still :slight_smile:

Interesting regarding the samples and the CPU load - If I were to increase it to 20MHz what would be the benefit (assuming there are no lost samples)?

Without further investigation, I don’t know what the problem is with the aerial yet. It’ll get stuck on an analyser and tested and perhaps taken apart to see what’s wrong with it. We’ve replaced it with a twenty quid jobbie from eBay

As tempting as it is to start tweaking things, I think I’d like to leave it running for a few days on the current settings and see how it performs. I’m seriously thinking about taking my own receiver down and swapping the RTL-SDR dongle for the same kit we’re using here :wink:

It’s hard to say, oversampling can help with overlapping messages. For example you receive two messages from two different planes with one message being a bit stronger than the other.

If the phase of the digital encoding is different then you can in some cases receive both or at least the stronger message.
2 MHz would be no oversampling, 12 MHz already is a lot of oversampling so the additional benefit of 20 MHz is hard to judge and probably is different setup to setup.

With short cables i’d probably reduce the gain to 17 or even 16.
(But it’s clearly already working really good, the weather is excellent for reception as well!)

I’m surprised that 20 MHz worked for you though with that many planes and messages.
Probably it depends a lot on the power supply being rock solid and having good cooling.
Still i’m a little confused that it worked at all.

Could you post your /boot/config.txt ?

Maybe you made the wrong changes artificially reducing CPU power.
I was really confused that 20 MHz didn’t work for you.

hello wiedehopf, good to hear from you. i took the “proverbial” step back. i went back to a 3B and did a clean SD install still using the mini. all work working VERY well with the mini until spring arrived in the southern united states. i am surrounded by
lots of tall pine trees and oak trees. the large leaves from the oaks came back (filled with spring time water) and the pine tree needles grew and lots of sap…my stats went down and my ranking went from the mid 1400’s to mid 1800’s over a 4 week period.
this is my first spring with the system (i just started feeding data last july). at first i was worried re water in a connector, a hardware issue, etc but checked and all seemed well…so for the moment i cannot provide boot/config.txt files for the 3B+.

Just thought you were trying for 20 MHz again because you were asking about boot/config.txt :slight_smile:

Trees will be trees, quite a few people on this forum in the US have the same issue!

Not real i’m afraid.
Just remembered that for a short time airspy-conf made it so the messages are duplicated getting to dump1090-fa. (only for the piaware sd-card case)

Can you run this:

sudo sed -i 's/ -c localhost:30004:beast//' /etc/default/airspy_adsb
sudo systemctl restart airspy_adsb dump1090-fa

It’s fixed in the current version of the install.sh script or at least i hope so!

Anyway the reception is still phenomenal, just the numbers won’t as outlandish as they are now :slight_smile:

Have done