A question regarding ADS-B out capability on a Mode S transponder. Can
you feed the output of a glider GPS, say a Volkslogger, and into the
Mode S transponder?

Since the transponder and the encoder both require TSOs for use in the
USA airspace, I assume the answer to this question is an emphatic
"no".

A similar question for ADS-B in - are you required to display the TIS-
B and/or FIS-B data on a TSOed display?

-John