| 摘要 |
FACSIMILE RADIO COMMUNICATION SYSTEM HAVING MULTIPLE DATA SPEEDS Kerry S. Berland A communication system which enables conventional telephone-type facsimile apparatus to reliably and efficiently communicate over a conventional two-way voice radio communication system. The system includes an interface unit which is connected to the facsimile apparatus and to the transceiver apparatus of the radio communication system without modification to either unit. The interface unit transmits and receives information over the radio system in the form of a series of data packets, each containing origin address, destination address, send sequence and check digit information for optimum transmission accuracy and efficiency. A confirmation packet of like send sequence sent by the receiving unit when received at the transmitting unit verifies transmission. In the absence of such verification the data packet is retransmitted. To optimize data transmission in the presence of weak signals or noise on the radio channel, the information packet speed for a link between two stations is selected adaptively as the highest available data speed which yields a predetermined maximum bit error rate. Packets controlling access to the radio channel are sent at a common lower network packet speed, thereby providing mutual intelligibility of all devices on the channel. Before information packets are transmitted at the higher information packet speed, the channel is reserved for a specified time period by the exchange of channel reservation packets, notifying units in radio range of the transmitter and receiver that the channel has been reserved, thereby avoiding packet collisions which might otherwise be generated by units which could not readily detect differing data speeds on the radio channel.
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