Re: "Unless a time stamp is sent I do not see how a handshake initiated by the a/c would allow signal transit time to be calculated by the satellite"
The expert interviewed on CNN clearly said that at a regulated time interval (1 hour?) the satellite initiates the handshake attempt with a faint ping something like " are you there, got anything for me", and seems to id the a/c is same handprint as last time, and how far way it is based upon ping return time.
IE; The a/c did not initiate the pings we are hearing about.