FlightAware Discussions

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


#161

My -x doesn’t produce nothing bad (or not in that range). I just turned it off and teh msg/s remained more or less the same.
I’ll let it run like that for a couple days.

PS: My raspi-config says “This Pi cannot be overclocked”


#162

Well not by raspi-config. You can put in arm_freq=1250 for example. Doesn’t mean it’s gonna work, could corrupt the sd-card and such fun or just run unstable i guess.


#163

This worked:

arm_freq=1350
core_freq=500
over_voltage=2
force_turbo=1
boot_delay=1

For now, while it’s cold in my garage. In the summer might be a different story.

pi@pi_3:~ $ vcgencmd measure_temp
temp=44.5’C


#164

Side Note- My observation is that with -m 20, and without -p, FA mlat does not work. No errors indicating dropped samples, clock drift, etc., it just will not synchronize to any nearby receivers. With -m 20 and -p, it works fine.


#165

Curious. Are you using Ethernet or WiFi?

Which Pi hardware version are you on and what are typical message rates?

Also note depending on how you start airspy_adsb you wouldn’t see something like lost samples.
You need the option -v and some redirection if you are starting it via rc.local.


#166

Well, it is probably a bit expensive if you just want to experiment with it and see what it can do. But if you are after maximizing your stats it is probably a reasonable option, if your location and the rest of the equipment can reap the benefits of its capabilities.


#167

Some people have been known to own a Mode-S Beast or a Radarcape. (Way more expensive)
In light of that the Airspy Mini surely is a reasonable option :slight_smile:
(And the mini is probably competition for those devices when you combine it with a good LNA, haven’t seen a comparison though)


#168

The Airspy does need a LNA for max performance at 1090 Mhz. It is indeed competition for Radarcape in that way. This comes from friends that have first hand experience with the radarcape and airspy. Some even say that with the right setup tuning they get better results with the Airspy.


#169

You got it right. Yes that was exactly the reason I wanted to buy it.

Improving my stats and compete with other feeders has never been my objective. I never care for rank or streak.

Experimenting with, and developing low cost hardware (particularly DIY) has been my main field of interest.


#170

hello wiedehopf, i have been playing with gain values on my airspy mini. do you have a feel for how the RSSI values need to be set for optimizing gain? even when i see some values at 0dB i don’t see “interrupted” tracks. i do see that some targets “sit” for a while (ie no movement) when the values are consistently at 0dB. when values are -0.1, -0.2, -0.3 dB etc the targets move as expected and have no interruptions. any comments or should i seek input from prog?


#171

The RSSI values are not really comparable to dump1090 values when it is working with a dongle directly.
The calculation is very different.

For me with my limited range due to terrain i have pretty much perfect reception all the way from a gain setting of 11 to 21.

Right now i have my lowest RSSI values around -20 with a gain setting of 16.
Half my list of planes is from -1 to -0.1 basically.
(It seemed high to me at first as well but i got used to it)

With the rtl dongles it seems easy to really overload the mixer or something, but with the airspy the front end is set up much better and it seems really hard to overload.

I wouldn’t worry too much about it actually, the results seem near perfect over a wide range of settings.
What is the lowest RSSI values you see right now with your setup?
(not counting the -49.5 entries, those are from anonymous MLAT results not from the airspy)


#172

i see values near -20 and still get good “age” values. below -20 i see aircraft start to time out. this is with a gain of 18 at the moment.


#173

Pretty sure you are at a good setting. (2000 positions at > 200 nmi is really good considering it is mostly one direction)

Is it still on your second station?

Do you lose aircraft very close in?
I don’t have regular close in traffic, but i didn’t lose any tracks even when turning it up to 21.

You could just out of curiosity set it to 21 and see if you even lose any any local aircraft.

(Are you back on the splitter? I’m surprised you didn’t switch around your feeder-ids yet so that your airspy is on your primary stat page ;). But i guess as you don’t do ssh/putty you would need to type in the complete number which would be quite annoying)


#174

yes, the mini is still on the second station (89124). when the gain was at 21 i did lose tracks. also lost some tracks at gain of 20. i stayed on gain of 19 from 24 jan thru today and just changed to gain of18 one hour ago, so i will see if any improvements.
the splitter is not being used at the moment. i purchased a second FA antenna and 10 meters of LMR240 and put the second antenna in the attic (my wife won’t allow any more cables on the roof!) so i am running station 83471 completely separately. i just received the lmr240 today so i will play with gain there some over the next few days.(the dongle is the rtl-sdr v3 on that station) however, if the mini continues to do well in terms of aircraft and positions at even lower gain i am not sure the second station makes any sense (except for playing with new dongles etc)


#175

Try a gain of 15 for a day and check if you lose far out aircraft :slight_smile:

If you don’t then you can safely put it on 16 or 17 and that will hopefully be fine for the close in aircraft as well.

Also be aware at least the displayed RSSI numbers are quite a bit different when switching to 20 MHz operation. (The optimal gain setting might still be the same though because the mixer and analog stuff before the conversion to digital is the reason for overload not the actual analog to digital converter, which the RSSI is based on)


#176

hello wiedehopf, on your mini, how many, if any, of your RSSI values are actually 0dB? i am now running a gain of 17 and still see between two values of 0dB for light traffic and up to 7 or 8 values of 0dB during periods of heavy traffic.
by the way, with the gain set at 17 my minimum RSSI values that still seem to get good data are at -22dB.


#177

I’m running 20 MHz and that changes RSSI values somewhat, anyway what you are describing sounds perfectly fine.

That is how my list sorted by RSSI looks like, sorted from top and bottom:


#178

hello wiedehopf, i just purchased an RPI 3B+ and will receive tomorrow (16 feb). i wish to try M=20 on the mini so purchased a B+. can i simply swap the SD card from the 3B and should all work well or are there other things i need to do?


#179

simple swap should work fine.

still for running m=20 run the install script again and do your configuration.
(the old install script has different network settings resulting in much more CPU load)


#180

perfect, as usual…you are a great resource for this community