Posted for "Lennart Persson" <lpn@ilen.se>:

 Skip,
 
 ADS-B stands for Automatic Dependent Surveillance - Broadcast, and it can be
achieved thru the extended Mode-S squitter ADS-B messages or thru VDL-4.
Biz-jets and airlineres are or will be using the Mode-S messages to update
thier TCAS.  Mode-S transponders are in this case just a transmission source,
and VHF Datalink Mode 4 (using 108-138 MHz) is another communication vehicle,
and has about the same information as the Mode-S squitter.  It would be
interesting to see what the plans are for extending ADS-B.  It does require a
new radio in the air-craft, and I think Garmin will be happy to develop one.
 Lennart