公开(公告)号：CA1221431A

公开(公告)日：1987-05-05

申请号：CA514639

申请日：1986-07-24

Applicant: MOTOROLA INC

Inventor： KREBS JAY ,  FREEBURG THOMAS A

IPC: G08B5/22 ,  H04J3/06 ,  H04L5/22

Abstract: A data communications system (Figure 1) is described in which variable length messages (Figures 3, 4 and 5) are communicated between a general communications controller (GCC 104) and a plurality of portable and mobile radios (130, 132, 134, 136, 138). The variable length messages (Figure 3) include a bit synchronization field (204), a message synchronization field (205) and a plurality of channel data blocks (203) for efficiently and reliably handling long strings of data or text. Each channel data block (Figure 5) includes an information field (503), a parity field (505) for error-connecting the information field and a channel state field (507) indicating whether or not the radio channel is busy or free. The GCC (104) is coupled to a cellular arrangement of channel communications modules (CCM's 106, 108, 110, 112), which each include a radio transmitter (114, 120, 124) and/or radio receiver (116, 118, 122, 126, 128). The mobile and portable radios (130, 132, 134, 136, 138) communicate with the GCC (104) by way of the CCM's (106, 108, 110, 112).