Abstract

A method of encoding silences during transmission of data packets separated by silences consists in transmitting alternately during each silence two types of empty half-bytes which are mirror images of each other and the first two bits of which do not comprise any median transition and thus do not conform to the Manchester encoding law. According to this method, sending of the last data half-byte of a packet in Manchester code by the transmitter is followed by an empty half-byte yielding a transition with the last bit of the last data half-byte. The transmitter and the receiver may be connected by a single link which then carries the clock signal continuously through the intermediary of the data half-bytes and empty half-bytes. The transmission device comprises a transmitter, a receiver and one or two transmission links. In the transmitter an encoder comprises a read-only memory addressed by the information to be transmitted, this information relating to the packets and the silences, and delivering data half-bytes and empty half-bytes. In the receiver a decoder is addressed by the data half-bytes and the empty half-bytes and delivers the corresponding information. The transmitter also comprises a clock and a differential transmitter. The receiver also comprises a differential receiver and:in the case of two links, a circuit for choosing the phase of the clock signal,in the case of a single link, a circuit for reconstituting the clock signal. The receiver also comprises a circuit for detecting loss of the clock signal.

Other References

• Electronic Design., vol. 30, No. 16, Aug. 1982, pp. 201-212, L. Sanders, "For Data-Comm Links, Manchester Chip Could be Best"