Hey everyone. Very new to all of this but I got my piaware up and running with both 1090 and 978. I noticed earlier that on the 1090 map, about 10 planes were being tracked on the ground by TIS-B but they were only there for a minute and went away. It happened again maybe an hour later and hasn’t shown up again since. Anyone know why it is unstable in reading that data when I’m only a few mile from KPHL and the antennas are mounted on my roof with a clear line of site to the airport.
Any other tips or tricks would be greatly appreciated!
TIS-B (and ADS-R) is not always broadcast, there needs to be a suitable client aircraft around:
Once the above criteria have been met, the ground system will identify the aircraft as a TIS-B/ADS-R “client” and using the client’s ADS-B Out position information it creates a “hockey puck” around the aircraft. The “hockey puck” is 30 nm in diameter and +/- 3,500 ft.
Any “not-on-the-same ADS-B Link” aircraft that falls within the “hockey puck” will be transmitted via ADS-R on the appropriate ADS-B In link to the “client” aircraft. Similarly, any non-ADS-B Out Transponder equipped aircraft within the “client” aircrafts hockeypuck will be transmitted via TIS-B on the appropriate ADS-B In link.
So in your example, to see 1090MHz-only ground traffic retransmitted on 978MHz TIS-B/ADS-R, there would need to be a 978MHz-in-out (and no 1090MHz in) aircraft within 15nm / 3500ft of the airport and visible to the FAA’s ADS-B receiver network.
or did you mean you’re hearing 1090MHz TIS-B? Either way, it’s largely at the mercy of what the FAA does, and it can pop in and out a bit, beyond what they document above.
I can see 1090 MHz TIS-B from LAX which is about 90 miles north of me. As you say it goes on for a few seconds and then disappears. TIS-B is probably useful for pilots, but for plane trackers it’s kind of an annoyance.
Note that you can turn off TIS-B in SkyAware. There are 4 toggle controls below the list. I turn off TIS-B as well as “Other”:
