I looked this info up a while back when the subject came up in an unrelated thread:
The Icom F50V "whisper radios" used by Nude-O-Scope operators transmit VHF analog. They can use voice inversion scrambling which makes voices sound like Donald Duck, although this technology has been around for decades, used in consumer electronics, and is easy to defeat. Just Google "voice inversion descrambling".
More on the "whisper radios"
here, listings of frequencies used by the TSA
here.
Originally Posted by
eyecue
The channels are encrypted.
The TSA does not use encrypted comms. TSA supervisors, BDOs, etc use Motorola XTS radios with the
APCO P25 digital standard, which can easily be listened to with
scanners designed for the radio hobbyist.