Data transmission system

摘要

A data-transmission system using a continuous ARQ system, wherein a block (word) synchronization code is transmitted through a transmission line from a transmitter to a receiver repeatedly at a predetermined time interval, until the transmitter receives a signal (ACK) denoting the detection of the synchronization code from the receiver. Upon receipt of the synchronization code detection signal, the transmitter issues data blocks each having a fixed length to the receiver continuously from the point of time at which the succeeding synchronization code is to be transmitted. In the invention a predetermined number of test data blocks are further transmitted to the receiver in succession to the synchronization code. The receiver examines a block error rate concerning the test data blocks and supplies the transmitter with not only the synchronization code detection signal but also a data rate-specifying signal. The transmitter delivers data at a rate dependent on the data rate-specifying signal.