Abstract: Data words of non-standard length are used to communicate optional messages with non-standard meaning in an interrupted-clock, bit-serial data transmission system which employs a timing channel and one or more separate data channels. In an interrupted-clock digital data transmission system, interruptions of clock pulses in a timing channel are used to identify individual data word groups in the simultaneous messages on one or more data channels. According to the present invention, message words constituting groups of data bits more or less in number than some standard value are used to communicate optional messages with non-standard content or meaning. Such altered-length message words may be used, for example, to monitor the operation of the transmission system itself and to control its operation. They make efficient use of the available system bandwidth. A clock regenerator circuit is described which is an improvement over the prior art for altered-length messages.

Abstract: In a bit-serial type data transmission system using the interruption of clock pulses in the timing message to identify separate data word groups in the data messages, a method and apparatus for recovering the transmitter clock oscillator frequency and thereby identifying the interruption interval. The method and apparatus in addition provide signals which may be employed to control the reception of the serial data word groups, to indicate the availability of the data groups as bit-parallel words, and to provide for the retransmission of the received data word groups or the transmission of other word groups.

Abstract: A high performance asynchronous system and method for continuous communication of data from an originating station to a destination station. Data messages are transmitted over one or more transmission channels between the two stations, and a timing message is transmitted over another transmission channel. The data messages are divided into logical groups, called words. The timing message contains a periodic signal for synchronizing the reception of the data messages. The data word groups are identified by interrupting the timing signals in the timing message.