Talkback Base stations, handsets, walkie-talkies for off air communications, off air communications via walkie-talkie (portable) and base station.
The frequencies listed for talkback are mostly in pairs. This is because they are designed for duplex (Base Tx/Rx, Portable Tx/Rx) operation. For simplex use either half of the pair can be used; continuous transmit (base half) or press-to-talk (portable half).
Standard powers are 5W base and 1W portable for outdoor use, 1 W base and 100mW portable for indoor use.
Standard bandwidth is 12.5kHz.
Assignments are calculated and issued on the basis that the radio equipment is manufactured and used in conformity with the UK Interface Requirement IR 2038, this requires the use of Isolators (circulators).