FlightAware Discussions

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

This is the first time this problem has come to my attention.
If you read the quickstart guide on the airspy page, it’s clearly stated:
https://airspy.com/quickstart/

Anyhow a note that a firmware update may be required if your Airspy is older than 2016 might be a good idea.

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Speaking of Airspy… I have tried different sampling frequencies and I don’t understand the benefit of using higher SR.
I can use 12, 20 or 24… great. But for higher SR I need to lower the “e” to “fit” into my one core CPU 100% usage.
To me it almost looks like the benefits of running at 24 or even 20 with lower “e” are not so visible. Does anyone see the same, or is just depending on the local conditions and the actual CPU capability?

I’ve mainly focused on finding the right combination between -e, -w and gain. Running 20MHz SR and a somewhat overclocked RPi4 with passive cooling.
From my experimentations I’ve found that some gainlevels give a higher CPU load than others. My system max out if the gain is 18 with -e 10.4 and -w 5. CPU is lower if the gain is higher or lower. I suspect (but can’t prove) that this is some kind of “sweetspot” for my system and location producing the best signal quality for the system to work with, but I can be utterly wrong :crazy_face:

Got inspired by your post so I’ll try to lower the SR to 12 for some time to see if that makes any noticeable impact on the performance/stats combined with changes to -w and -e.

My post had a mistake, I meant as variable the -e. The -w is the default 3.
In my case, at night, when are less planes, the CPU usage goes high. Since I don’t think I am missing anything interesting, I let it hit 100% on one core in that case (just a few flights).
So, to keep variables at minimum, I am interested in the trade-off between the Sample Rate and -e.

Are you just referring to SDR radios, or will a system backup to USB also cause problems?

Anything that uses a fair amount of data can cause problems.
The USB 2.0 bus is limited to ~480Mb/s. The airspy uses a lot of this.
You can use devices that don’t use much bandwidth, maybe a GNSS/GPS dongle or something powered by USB that doesn’t use much or any data (a uputronics amp for example).

A system backup to USB would use a lot of available bandwidth. If the backup device is USB 3.0 and plugged into a 3.0 port on an RPI4 then you may be OK.

I’ve never found a combination of settings where SR=20 that come close to receiving the same number of planes / positions I can get with SR=12. Just guessing, I’d say I easily lose 20% of decoded messages when operating with SR=20. This is on a dedicated Pi4, no lost samples.

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I am on a i7 CPU, so the -e values are higher than on a Pi4. Supposedly after a certain value, there are only diminishing returns. So that’s why I have asked…

I have a system running with a Flightaware Pro Stick Plus v.1.0 since about three years. Recently I upgraded my NAS system (24/7 system also running the ADSB stuff) and got the idea to test my Airspy as an ADSB receiver. I setup the system using the scripts provided by Wiedehopf (thank you very much). Testing with various combinations of gain and -e ´, I never achieve the same or better performance than the FA stick. Average message rate and number of positions stays 10% lower. The CPU load with -e 10 is now about three times as high compared to dump1090-fa, wasting a lot of power for no gain. I’m a bit frustrated but on the other side the FA stick has a brilliant price-performance. Btw I use it with a F5ANN designed PCB antenna mounted on my roof nearby Stuttgart.

Markus

You will need a filtered LNA, uputronics or rtl-sdr:
https://store.uputronics.com/index.php?route=product/product&path=59&product_id=50
https://www.rtl-sdr.com/new-product-rtl-sdr-blog-1090-mhz-ads-b-lna/

Or do you mean the antenna you have already has an integrated amplifier/filter?
“F5ANN designed PCB antenna” is a little ambiguous.

Without amplification the FA antenna or similar will outperform the PCB antenna you mentioned any day.

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you are right, the LNA I use with the Airspy Mini has no filter its a general purpose device. My antenna is the version sold by Jetvision in 2014 without the integrated LNA but housed in a weatherproof casing. The FA stick has an integrated filter and LNA. Might buy the FA antenna someday…

Do you use that LNA with the FA ProStick+ as well?
Some LNAs will actually completely mess up your reception because they are just bad or getting overloaded by out of band signals.
Maybe try without it and the Airspy Mini on maximum gain?
But with a low gain antenna like yours it’s not gonna give good results.
Probably the cabling can also use some attention.

Most ppl using the Airspy already have the rest of their system optimized, a somewhat decent antenna with a lowloss coax run to an amplifier.
Every 0.5 dB counts between antenna and LNA.

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no, I have not stacked the LNAs :slight_smile: I have tried the Airspy at max gain without the LNA with inferior results. Both setups can detect airplanes at up to 340km distance. I regularly detect planes nearby Liege (Lüttich) and I’m located just 15km away from EDDS. The FA stick setup creates more positions but not a higher avg. message rate. So I conclude that it can decode a bit better because of less interference.

I upgraded my setup to Airspy R2 and Raspberry PI 4 yesterday.

Thank you Wiedehopf for your airspy setup script.
It made setting it up very easy and quick.

For the first time I am hitting 200 airplanes with positions (was about 160 on a good day)! Message rate was 1.100-1.200 and is now 1.800

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Hi all,

I see there is an upgrade to the Airspy mini (and R2) firmware:-

I’ve applied it and seems to have improved my starts again (although it’s hard to tell because aircraft numbers are so much lower).

Has anyone else seen that or able to provide more “quantitative” comments on what impact that firmware change makes?

Stay safe!

Kind Regards,

Andy.

Hi @AndyBailey I have a reference site plus an Airspy mini site with gain(s) carefully adjusted on each so that performance of each sites are near identical…

2xSites#stats-123922&#stats-117925

Yes there are two lines on that graph :wink:

I am ideally placed to try out the latest firmware and report back.
Probably need a few days traffic to spot any real difference, but at least I can leave the reference site alone and only disturb one receiver.

Will get back to you.

BTW, there was a bit of a Tropo lift on this morning (I’m in Wiltshire, UK) . I first noticed Band II FM around 6am I was getting distorted stereo. Then I started getting end-stop signals from BBC Wales, far stronger than my local stations. I wondered if the opening might manifest itself on 1090Mhz and sure enough I was getting email alerts from my tropo monitor, which was set to alert on stations at low elevation angles and/or > 290 miles (usually 50 miles more than I regularly get). I was seeing aircraft out to the west at 330+ miles. Curious thing observed was that aircraft would appear to the South of Ireland for few minutes then disappear only to return when they were around 275 miles.

The reason I mention all of this is, I have learnt through experience that doing any kind of tuning / adjustment or general comparisons during a period of high pressure or Tropo can be misleading.
So I’ll probably let it settle for a week with the new firmware before coming to any conclusions.
73 Howard

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Hi @hphillip

That’s very interesting! Great piece of work there and interesting comments. I must look a bit deeper into it.

It does look like you have seen an increase in traffic in the past few days too. As you say probably wise not to leap into an upgrade unless traffic is steady.

I’ll look forward to seeing your thoughts when you do upgrade though!

Kind Regards,

Andy.

The comment I made in another thread is valid here:

Hi @LawrenceHill @AndyBailey

Just thought I would just get back to you guys after a few days data collection about the impact of the new firmware update on the Airspy mini.
Basically: it has certainly not done any harm and at the very least I feel more comfortable being on the latest build even though the phase noise improvements are only applicable to the R0/R2.

I have my reference site (non-Airspy) which always does better on number of aircraft but conversely the Airspy always does better on number of positions.

The only metric I can demonstrate a difference post-update is to conclude that the Airspy is getting closer to my reference site in terms of aircraft reported.

Any improvement is very minor but the two sites are now quite close on the UK ADS-B statistics page.

(Airspy is the bottom one highlighted and as you can see does better than top one on positions, but it’s a tiny difference in practice)

As the traffic starts to increase over the coming weeks it will be interesting to see if the gap changes. However I am keen to try out a filter in front of the Airspy and play with the gain on that one a little more, so it will invalidate the current comparison test I am running.

Thanks for the update.
Just for information, my Airspy (also a mini with the latest firmware) does better than my reference site (a ProStick plus) on both number of aircraft and positions but only by a small margin.
The Airspy is site 97430
The ProStick Plus is site 72716