On Friday, December 18, 2015 at 11:23:25 AM UTC-8, Darryl Ramm wrote:
On Thursday, December 17, 2015 at 9:49:30 PM UTC-8, Mike Schumann wrote:

One thing that you should think about if you want to be fully 2020 compliant is that you buy a Trig21, NOT a Trig22 transponder. The Trig22, while it is ADS-B OUT compatible and will trigger the ADS-B ground stations, is NOT 2020 compliant.

Good advice, if buying a transponder now and wanting best ADS-B options/flexibility in future. But in the big picture again this may change if TABS carriage regulations happen (the TT-21 meets TABS power requirements even if it does not meet ADS-B out power requirements).

OK thanks for the private emails :-) Doh I did not spot the (likely accidental) transposition in Mike's post. To be clear the lower-powered Trig TT-21 does *not* meet the ADS-B out requirements in the USA. You need a higher-powered Trig TT-22 (and certified IFR GPS source). But as I said, TABS devices have lower power requirements so if TABS is adopted a TT-21 should be usable as a TABS device (and that includes triggering all the ADS-B ground infrastructure base services). But since there are no TABS installation or carriage regulations yet we have no real idea about any of this actually happening.