Abstract: In a digitally trunked radio repeating system that may include several radio site repeating transceivers, a site area identification coding system to ensure that transmissions intended for one site or as one mode are not decoded by another site or as another transmission mode. In particular, a site or transmission mode identification byte is used in the transmission error coding (CRC) scheme applied by both a mobile transceiver and the radio site repeater. Since the identification byte is used in the transmitter to calculate the CRC error correction data, the same identification byte must be used in the receiver to decode the CRC value. The intended radio site or transmission mode wilt apply the proper identification byte to decode a transmission. The wrong radio site or mode will not correctly decode the CRC value in a transmission because the wrong identification byte will be applied to the transmission.

Abstract: In a trunked radio communications system, apparatus and methods are provided for transparently updating existing frequency division multiple access (FDMA) communications facilities to accommodate time division multiple access (TDMA) communications. TDMA channels are added to existing FDMA sites on an individual basis to increase spectral efficiency and capacity while still being compatible with existing FDMA equipment and protocols. For example, the existing FDMA control channel and protocols are used by dual mode sites and dual mode radios. A dual mode radio transceiver selectively participates in trunked radio communications in either an FDMA mode or in a TDMA mode. Each dual mode radio includes a memory for storing a mode identifier identifying each channel as an FDMA or a TDMA working channel. When a channel assignment is made, the dual mode radio determines from that channel mode identifier stored in memory whether to operate in the FDMA or TDMA mode for that particular communication.