Electro-control system for data transmission

Claim 1

An error control system for transmission of data between a transmitter and a receiver, the transmitter comprising: means for transmitting successively a series of block signals each formed of data, a block number code and an error-detecting code to the receiver through a forward channel; means for detecting a negative acknowledgement including a block number designation designating a block signal in which an error is detected at the receiver means for detecting a false negative acknowledgement sent forth from the receiver; means for inverting all bits of a data signal or an error detecting code being transmitted upon detection of the negative acknowledgement; means for transmitting the inverted data signal or the error detecting code to the receiver; the receiver comprising: means for detecting an error from at least the data signal included in the block signals received and means for sending forth through a backward channel the negative acknowledgement upon detection of an error to cause the transmitter to again deliver block signals, the first one of which is a block signal corresponding to the block signal found erroneous.