FlightAware Discussions

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

I am using the RTL-SDR ADS-B LNA which could use up to 150mA. Considering the Mini has a bias-tee with a 50mA limit would that cause the dongle to shut down?

I didn’t realize the Mini was only 50ma bias-t rated. Thats a huge problem. Power that bad boy through other means or you’ll wind up with a useless $100 radio in no time.

The whole USB port has 500mA capability. Maybe less on the Pi3.
So anything that needs to be fed-trough will deduct from that amount.

Considering that the outside LNA can fail in a short-circuit state, I never trusted feeding them from a $99 (or $169 in my case with R2) receiver.

Raspberry Pis don’t particularly follow the USB power standards. There is no 500mA limit per port, rather there is a total allowable USB current supply of 1.2A for the Pi 3 onwards. This total is for all ports, but can be drawn through any single one. The Pi 2 had a 600mA limit but was software switchable to 1.2A.

Ya I don’t get it. I have a Pi 3B+ with only the Mini plugged in in 12MSPS mode. It shouldn’t be a power issue unless my Pi board itself has a problem. I can run a Nooelec dongle with a built in bias-t with no problem. I’ll try an external bias-t I guess. Unless my Mini has a hardware issue.

Just as a follow up, I received an external bias-t and the problems I was having with the Airspy Mini stopped. It must have been an issue with pulling too much power from the internal bias-t in the Mini.

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On another note, is there any benefit to pointing other feeders at port 47787 that the auto script sets up for airspy_adsb instead of port 30005 that beast-splitter is using? Is beast-splitter forwarding everything coming out of airspy_adsb verbatim? Can airspy_adsb handle more than 1 connection?

Airspy_adsb can. Not sure about CPU though on slower RPI 3s and 4s.

Just wanted to follow up on this. Turns out I have a 3B+ that had gone bad and that was causing my problems. It must have an issue with either power delivery or the USB controller. I had switched everything except the RPi, so I swapped in an older RPi 3B that I had laying around and all my “Decoding Stopped” issues went away.

Another question.

I just upgraded from my RPi 3B to a 4B. I also have put the Airspy Mini in 20MSPS mode. When I do that I see a decrease in the reported RSSI for my traffic. There’s just a general decrease that you can see on the graphs. Is this a real decrease in signal strength? Should I bump the gain up a notch to compensate for running in 20MSPS mode? Previously I ran the gain such that my weakest signals were between -15 and -20dBFS. After 20MSPS they are now around -19 to -24dBFS. Is it advisable to bump the gain?

Thanks.

Oh and special thanks to Prog and the other contributors to the Airspy ecosystem. Works great.

Check what works best for you. Here’s an idea: Thoughts on optimizing gain

I’m running it so the weakest signals are around -36 dBFS and i’m not noticing any degradation in performance.

Having the weakest signals between -20 dbFS and -30 dBFS is what i usually recommend.

But honestly, i’ve seen people run the gain so high their weakest signals were -10 dBFS and they still had good reception.
I couldn’t really determine much difference the whole range from the weakest signal being -15 dBFS and -36 dBFS.

In other words… the airspy doesn’t give a damn! :wink:

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I have to be somewhat careful. You can overload the Airspy Mini with too much gain. I’m also running an RTL-SDR ADS-B LNA and I live close to the local airport. If I run the gain too high I’ll get dropouts of planes on final approach to one of the runways, and I’ll get dropouts when the local police are flying their Cessna 182 overhead. In both cases I have direct line of sight so I’m thinking it must be just too much signal even for the Airspy. It’s a real balancing act. I also have good distance coverage. Over 200nm in all directions. So I also want enough gain to grab that traffic. That’s why I went for the Airspy. With my old dongle it would have a lot of dropouts of close in traffic with the gain set for distance. But the Airspy is much much much better in that regard.

Not really, just lower the gain even more if you like local traffic.
Almost sure you won’t lose long range.

Try a gain of 12, see if you lose range!
(i’m running the rtl-sdr LNA as well)

What i was saying is that you have a pretty wide margin.
Though i’m not sure, i think sometimes the rtl-sdr LNA itself might be overloading itself. (very strong and very close aircraft, i sometimes have helicopters literally flying 200 ft above my house, overload only seems to be while they are within half a mile or so)

i also use an airspy mini and rtr-sdr 1090LNA. my gain is set to 16 so that i don’t dropout local traffic. my local airport is about 1.5 nautical miles away and i occasionally get departing traffic 500 meters or so above my antenna. i still see peak range of over 250 nautical miles. i recently changed gain from 17 to 16 to eliminate the occasional dropouts. i have seen a slight drop in my stats but i figure giving better “close to airport” data to FA is much better than being higher in the stats by seeing aircraft that many other sites also see.

Well I took your challenge and ran with gain 12. Interesting results. At 12 I did lose a little range, but not nearly as much as I would have thought. What I lost more of was position consistency at the limits of my range. I wasn’t getting as many messages and positions from planes at the limit of my range. Which really isn’t unexpected. I suspect the trees around me are having a big effect on those long range signals. My antenna is on top of my house but in some directions I have very tall trees that I could never realistically get over, and they are certainly attenuating the signal. With gain cranked up I can get more of those far messages but then lose some close in. I have reset to a gain of 15 and will start creeping it up from there after a couple days of westerly winds to make sure I’m not losing traffic on final.

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@obj Does beast-splitter forward everything it receives from airspy_adsb to a connection on port 30005?

I don’t know how you have beast-splitter configured. In general, it will forward all messages from the source connection to each client after applying the requested per-client filters.

I am using the SD card with an Airspy Mini and the auto setup script.

    piaware-config receiver-type relay
    piaware-config receiver-host localhost
    piaware-config receiver-port 47787

that’s what the setup script does.

You can connect directly to airspy_adsb on port 47787 if you want.
At some point it was using significant CPU per extra connection but that’s been corrected.