FlightAware Discussions

ADS-B Exchange with FA add on

System(s) Running two while I experiment
Pi 4
SD Samsung 32 g pro +
Same antennas and within 200 feet of each other.
I’m changing builds but always the latest image provided by ADS-B Ex or FA

System 1:
ADS-B EX running as primary build with FA as an add on. Feeds stats but I’m unable to connect to the “live data” via "ip_address:8080 or via my FA login. The ADS-B feed works normally.

System 2
FA image running as stand alone. “Live Data” is easily seen via the FA login and the ip address:8080.

System 1 is reporting considerably more positions than system 2 configured as above. In a 24 hour period system 1 is reporting roughly 340,000 positions a day with system 2 reporting around 20,000 fewer positions.

As a test I pulled the SD card on system 1 and put in a FA only build and now system 1 is reporting fewer positions than system 2. System 2 has a slightly higher antenna with everything else being equal. So that is to be expected.

If I could get my “live data” from FA on system 1 I’d be a happy camper and just move on.

FA provides some features that the other feeds do not which is why I prefer using their feed to view my stats and live data…

Ideas?

Greg
NZ6E

How are you comparing positions between feeders? Using your FA My ADS-B stats page?

Yes, Comparing daily stats.

My account will show 3 feeds. The inactive feed is the one that was ADS-B Ex with FA add on.
142295 is the inactive feed.

From what I understand, that site has the ADSBx image and you’ve installed piaware on top of it? Did you install dump1090-fa? That is what will allow you to access live data on SkyAware

No, I did not load the dump 1090-fa
Not sure how to go about changing the dump 1090
So that will fix the live data issue but what about the discrepancy in the positions seen?

There is something in the software that is making a difference in what’s being reported.
I’ve tried changing the receiver setting.
rtlsdr MAX to rtlsdr -10
And then to beast
No difference

Don’t use the adsbx image if you want to run dump1090-fa, simple as that.

You can feed just fine with piaware but changing the decoder isn’t something that is planned for.
(it’s not on the piaware image either by the way)

That’s just a local webinterface.
Change the :8080 to /tar1090 and you will get a live webinterface.
Remove the :8080 and it show you the web interfaces available on that image.

I don’t see why there would be a difference.
Are you sure you’re using the same gain?

Also you should link these pages: https://flightaware.com/adsb/stats/user/nz6e#stats-142969
and note which receiver is which.

Receiver gain.
IIRC the gain is set on the ADS-B Ex config as -10
The FA image is set to MAX which sets the AGC on.
Also I think ADS-B uses beast as the receiver type where FA uses rtlsdr type.
What is the max gain that can be set?

/tar1090 doesn’t give the same features as FA does. The single click to get the flight plan/schedule. Minor I know because I could click on the FA link on the page and get the info as well.

The curious thing is why did the ADS-B config track so many more aircraft than a standard FA build?

Well installin dump1090-fa will cause you trouble so i’d recommend against that.

As for the links: https://github.com/wiedehopf/tar1090#enable-disable-fa-links-in-the-webinterface-previously-enabled-by-default

I’m not sure if max uses 49.6 or -10.

-10 usually results in around a gain or 55 … that’s empirical.

pgrep -a readsb
pgrep -a dump1090-fa

That should get you the gain actually being used.

I’ll reload the dual feed, system 1, and take note of the gain. With the single feed (currently just FA) I’m seeing -10.

Thanks for the help!
Still upgrading!

Gain with ADS-B is 46.2
And I filtered ADS-B by military aircraft… I found a difference! Including seeing a U2 flying at 50,000 up around Beale AFB and a couple military that aren’t on FA.

Not sure if that would account for the 20,000 position difference but who knows.

I’ll fiddle with the gain on System 2 and see if I can see any differences. I believe ADS-B and FA are using two different scales for gain.

In the meantime, ADS-B wins for what it can see (and it’s feeding FA more info than the native FA image did.

piaware doesn’t use adsbexchange MLAT results. (neither does adsbexchange use FA mlat results)

Well the lower gain works better then.
Set the same gain and it’ll probably perform pretty much the same.

No they don’t.

It’s readsb and that is in regards to the decoder more or less still the same as dump1090-fa (it’s a fork of dump1090-fa).
So they really shouldn’t perform any different.