Bogus Ground Returns


#1

I have been consistently seeing numerous bogus ground returns since I started using FA dump-1090 v 3.1.0

The returns are showing position data on the airport surface but no aircraft information or squawk.

Sometimes, FA dump-1090 will rectify itself and start showing accurate ground information from aircraft taxiing or airport vehicles.

I have verified this by driving over to the airport and visually checking.

While I’m more than happy to see my position statistics going through the stratosphere, I think we would all be better served if this bug were eliminated.

Has anyone else noticed this anomaly?

BTW,

I sometimes receive bogus shadow returns from close in departing and arriving aircraft but this issue is much less frequent than the one mentioned above.


#2

TIS-B or ADS-R maybe?


#3

Possibly, but I don’t know what that is. :blush:


#4

Does sound like TIS-B (this is where a ground station transmits radar-derived information in an ADS-B-like format for the benefit of nearby aircraft that have ADS-B in)

If the ICAO addresses are showing up italicized, and they are not mlat, then it’s almost certainly TIS-B. (3.1.0 doesn’t clearly show TIS-B separately, the next version improves this somewhat)


#5

I guess TIS-B must be it.

The information blocks for the displayed ghost aircraft are, indeed, italicized.

A Google search provided a little insight but didn’t take long to lose me.

aopa.org/news-and-media/all … s-to-tis-b


#6

I found some links
faa.gov/nextgen/library/med … t_ADSB.pdf
faa.gov/nextgen/programs/adsb/faq/
faa.gov/nextgen/programs/adsb/
faa.gov/nextgen/equipadsb/capabilities/
thebalance.com/what-is-tis-b-282714

Basically
TIS-B(Traffic Information Service - Broadcast) is Traffic Broadcasting on 1090 or uat 978.
It displays aircraft seen by ground radar and ADS-B receivers. Can include Mode A/C aircraft.

ADS-R (Automatic Dependent Surveillance–Rebroadcast) re-broadcasts 1090 to uat 978 and vice versa.
(US Only as the US is the only region that uses UAT 978)
Coverage is pretty good above 5000ft. It can be terrain shielded which is why some aircraft have receivers that cater for both 1090 and 978. Some even transmit on both.


#7

I can understand now why “Positions Reported” numbers aren’t used for rank ordering participants.