fastj22 wrote:I thought TIS-B was broadcast to all listeners in range and not only to those broadcasting SIL 3. And if there are no aircraft broadcasting ADS-B out, no TIS-B is broadcast. So I'm not sure how you would not broadcast it to just one receiver. At least that's how I understand it, which of course could be completely incorrect. :?
TIS-B are ADS-B transmissions
from the ground. The FAA will only (re)broadcast traffic within a certain distance of a known ADS-B target. That target must indicate that it is receiving TIS-B on that frequency (this is a pair of bits in one of the packets, 1090ES vs UAT) and meet any requirement the FAA deems necessary (e.g. SIL3).
You are right that anyone can receive those broadcasts, but unless you meet the various requirements, there is no guarantee that the FAA is broadcasting all the traffic relevant
to you.