| 摘要 |
A data communications system is overlaid on a voice-based trunked radio system (10). Digital data packets are transmitted over available radio channels, thereby enabling data communication between a host dispatch system (100) and mobiles (300) and a base station (200) in the trunked radio system. Radio channels associated with trunked channel groups are accessed when available by a communications controller (201). The communications controller is configured to communicate with various mobile units of the trunked radio system over available radio channels through multiple radio communication link (901). Radio channels are monitored to detect when the radio channels are presently unused for voice transmission and therey accessible for data overlay. In particular, when the data overlay system detects that the transmission of analog voice information ceases over a particular radio channel, the trunked channel group association of that particular radio channel is caused to be switched from a voice group to a data group. Data packets are then transferred over the available radio channel. <IMAGE> |
