FlightAware Discussions

PiAware 6 announced with auto gain

Hi there,

I’ve just received a newsletter about FA’s poll, and the biggest point to be seen is the announcement of PiAware 6 release, “in about 2 weeks”, to Pi (or Pi-like) receivers first, then FlightFeeder.
An “adapatative gain” is announced as the added feature.

Any thoughts on this, as I often wondered whether it was worth the hassle and neglected to test such a feature myself (and neglected to use the script available here: https://github.com/wiedehopf/adsb-scripts

Cheers,
Guillaume.

Tall order. And probably useless. The gain doesn’t need to be that variable in most places, because we have lots of simultaneous high level signals (close planes) and low level signals (far away).
The gain is always a compromise with the maximum dynamic range allowable by the ADC and the receiver’s noise floor.
Once you find that compromise, that’s the best.

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I will likely help at night when local aircraft traffic is low. You may be able to pickup more distant aircraft if the gain can be increased. Similarly when the local conditions are not good due to weather (Rain and Snow), you may be able to pick up more distant aircraft with a higher gain.

Will this work with the Airspy?

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So that means the Piaware image, or?

Gain is set in dump1090-fa, will this be modified installing the Piaware- Script? What happens to readsb users?

And Pi (or Pi-Like) is not mentioned directly, it only says “PiAware users”

  • And lastly, be on the lookout for a PiAware 6 software update to be released in about two weeks, which features a new “adaptive gain” capability that will help automatically optimize your receiver based on the aircraft signal levels around you. PiAware 6 will be rolled out to PiAware users first and then FlightFeeder users at a later time.

Yes, right. It is my understanding (possibly wrong) that both SD image users and custom installs will have the software rolled out at (about) the same time.

This is aimed more at having installs work acceptably out of the box without requiring manual adjustment of the gain (and in the face of SDRs with different frontends). If you’ve got a good manual setting dialled in, that’s better - but the majority of installs don’t do that (for example the OP!)

The default for upgrades of existing installs is to leave your gain setting untouched.

There is also the “burst” adaptive gain which does something that’s not currently possible with manual gain setting (decreasing gain when loud signals are seen); but that’s fairly situational and isn’t on by default.

It can work with other SDRs but currently only the rtlsdr code implements the gain-control hooks needed (and there’s no airspy implementation in mainline dump1090-fa yet)

It is a dump1090-fa feature so if you’re using dump1090-fa you can enable it.

readsb doesn’t implement this.

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Thanks for this detailed reply, @obj !

I’ve set my gain to have 5% of strong messages as a maximum, but with successive tests instead of automatic settings, I might have some interest in an automatism.

Just re set up some systems now with 5 and doing some gain adjustments and although currently my receiver, Airspy R2, does not accommodate automatic gain adjustments, you can do it manually. I wonder what they mean by ““adaptive gain””??

Yeah, will it just set an appropriate gain over time or dynamically adjust depending on air traffic, I wonder.

I’ve been playing around loads with gain recently, comparing 2 live setups, and basically, ignoring message rates, they both need to be maxed out at 49.6 or 4.5 - lower gains increase the message rate, but for me it lowers the aircraft seen, range and doesn’t pick up very local traffic well. It’s infuriating :upside_down_face:

It seems to me that this conversation is a bit like talking about drinking coffee.

Some people just boil a kettle and make a cup of instant coffee. They don’t much care which brand it is. Other people go to extreme lengths to make the ‘perfect’ cup of coffee - whatever that is.

Likewise, there are people who get a preconfigured unit with an SDR, and maybe an antenna. They plug it in and expect it to work. They don’t really care too much about how it works and they don’t really want to spend a lot of time fiddling with it - all they want to do is to watch what is going on near them.

Anyone who does want to know how things work will probably enjoy setting up everything themselves and keep trying to improve their results. Surely that goes for configuring the gain.

Isn’t it all down to what meets your needs?

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Very true - You can’t have the best of everything with this type of setup.
I’ve gone for most aircraft and range, at the cost of low message rates.
Will be interesting to see what the next FA does though, just out of interest.

Yep. It is a juggling act at the moment for sure.

I think that only the user can decide on an acceptable compromise but I expect an automatic setting would be very useful for the people who don’t care to fiddle with their system settings too much.

Hopefully, we’ll see a lot less threads from people who’s systems have been set to -10 and aren’t working very well. .Not that we mind helping those people out of course but it does make for a bad experience for some people and it might put them off the hobby.

I should add that an auto gain feature is available from @wiedehopf but although it is a recommended option in the excellent setup ‘cheat sheet’ from the same author, it isn’t a standard feature.

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Will PiAware 6 be based on Bullseye? Didn’t see that particular piece of information in the recent email from FlightAware.

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No, the sdcard images are based on buster.

Once the Pi Foundation has stable images based on bullseye we’ll look at migrating to that.

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I have installed Debian bullseye OS on my RPi Model 2 B and installed dump1090-fa version 6.0~dev on it. I had to build it from source-code (development branch). It is running with adaptive gain control:

adaptive: enabled adaptive gain control with gain limits 0.0dB (step 0) .. 58.6dB (step 29)

https://flightaware.com/adsb/stats/user/abcd567#stats-5252

 

image

 

pi@rpi2-20210823:~$ sudo systemctl status dump1090-fa
sudo: unable to resolve host rpi2-20210823: Name or service not known
● dump1090-fa.service - dump1090 ADS-B receiver (FlightAware customization)
     Loaded: loaded (/lib/systemd/system/dump1090-fa.service; enabled; vendor preset: enabled)
     Active: active (running) since Wed 2021-08-25 09:35:19 UTC; 6min ago
       Docs: https://flightaware.com/adsb/piaware/
   Main PID: 433 (dump1090-fa)
      Tasks: 3 (limit: 2001)
     Memory: 2.1M
        CPU: 3min 9.230s
     CGroup: /system.slice/dump1090-fa.service
             └─433 /usr/bin/dump1090-fa --quiet --device-type rtlsdr --gain 60 --adaptive-range --fix --lat 43.5xxx --lon -79.6xxx --max-range 360 --net-ro-p>

Aug 25 09:35:20 rpi2-20210823 dump1090-fa[433]: Found Rafael Micro R820T tuner
Aug 25 09:35:20 rpi2-20210823 dump1090-fa[433]: rtlsdr: tuner gain set to about 58.6 dB (gain step 29) (tuner AGC enabled)
Aug 25 09:35:20 rpi2-20210823 dump1090-fa[433]: adaptive: using 50% duty cycle
Aug 25 09:35:20 rpi2-20210823 dump1090-fa[433]: adaptive: enabled adaptive gain control with gain limits 0.0dB (step 0) .. 58.6dB (step 29)
Aug 25 09:35:20 rpi2-20210823 dump1090-fa[433]: adaptive: enabled dynamic range control, target dynamic range 30.0dB
Aug 25 09:35:20 rpi2-20210823 dump1090-fa[433]: Allocating 4 zero-copy buffers
Aug 25 09:35:30 rpi2-20210823 dump1090-fa[433]: adaptive: available dynamic range (26.4dB) < required dynamic range (30.0dB), switching to downward scan
Aug 25 09:35:30 rpi2-20210823 dump1090-fa[433]: adaptive: changing gain from 58.6dB (step 29) to 49.6dB (step 28) because: probing dynamic range gain lower b>
Aug 25 09:35:31 rpi2-20210823 dump1090-fa[433]: rtlsdr: tuner gain set to 49.6 dB (gain step 28)
Aug 25 09:35:40 rpi2-20210823 dump1090-fa[433]: adaptive: available dynamic range (37.1dB) >= required dynamic range (30.0dB), stopping downwards scan here
pi@rpi2-20210823:~$

 

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