Uniden UH8010S+ANT Owner's Manual page 16

Operation
Standard Operation without the aid of a Repeater station.
Operation with the aid of a Repeater Repeater Station (Duplex).
The signal coming from your radio is received by the Repeater Station
and the re-transmitted at the same time on another channel. This
operation is called "Duplexing".
For example,
CH01 on Duplex Mode will Receive on CH01 but Transmit on CH31
CH02 on Duplex Mode will Receive on CH02 but Transmit on CH32
etc...
If you transmit on CH01 Duplex mode, you are actually transmitting
on CH31 the repeater station down-converts your signal and
retransmits on CH01.
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UNIDEN UH8010S/UH8020S UHF CB Transceiver