[FedCom] 149.9400 Help

[D. Ruhe]

I few month's ago a gentleman provided me with an extensive list of
frequencies to be used by the Civil Air Patrol.(
http://www.pitt.edu/~ruhe/cap.html ) Occasionally on 149.9400 mhz FM
I've been receiving what sounds like telemetry. I found information via
Goggle that states that this frequency is used for NavData. Could
someone in layman's terms explain what this is ? I am assuming it's some
type of satellite that provides navigational aid. Also can someone
confirm that this frequency is actually used for aircraft repeaters ?

Thanks in Advance

--Dan--