GB1223863A - Improvements in or relating to data transfer systems - Google Patents

Abstract

1,223,863. Digital transmission systems. MARCONI CO. Ltd. 27 June, 1968 [29 Sept., 1967], No. 44453/67. Heading H4P. To reduce the effects of error bursts on any one character in a series of characters to be transmitted the bits forming the characters are interleaved prior to transmission. In the case of a series of p characters each having n bits, a series of n groups of bits is transmitted, each group consisting of p bits. p/n or n/p is an integral number. Each bit in a group is a bit selected from a different one of the p characters, and each selected bit is of different order from all the others. Thus if the series of characters is A, B, C ... J (i.e. p = 10) and there are 10 bits/character (i.e. n = 10) one or the groups transmitted consists of the bits J1, I2, H3, G4, F5, E6, D7, C8, B9, A10. Bits forming adjacent groups are taken from different overlapping series of characters. Transmitter.-The series of characters is fed to a continuously stepping shift register having a little less than pn stages. The output from certain of the stages, regularly spaced along the register, are sequentially gated to a bi-stable which delivers the interleaved bits to the transmission channel. Receiver.-The circuit is identical to that at the transmitter except that the selected stages of the register are gated in the reverse order, the bi-stable then delivering the original series of characters.