how Simplex and Duplex works on UHF CB Radio

Simplex or Duplex Simplex channel systems use a single channel for transmit and receive. Advantage: as the simplest system configuration, there is reliability since only two radios are needed to establish communication between them, without any other infrastructure. Disadvantages: The simplex configuration offers communication over the shortest range or distance because mobile units must be in effective range of each other. Duplex means two channels are used: one in each direction. Duplex channel systems transmit and receive on different channels. Repeater are configured to simultaneously re-transmit the audio received from mobile / portables units. This makes the mobiles, or hand-helds, able to communicate amongst one another anywhere within reception range of the repeater footprint . Typically repeaters have a high antenna and high power, which allows much greater range, compared with a ground vehicle or hand-held transceiver. Advantage: duplex channels allow repeater operation which extends range (in most cases due to increased transmit power and improved aerial location / height) – especially where hand-held radios are in use. Disadvantage: If a radio cannot reach the repeater, it cannot communicate. In Australia the repeater network channels are Channel 1 to 8 repeater output Channel 31 to 38 repeater input Channel 41 to 48 repeater output Channel 71 to 78 repeater input