International Standard Electric Corporation

Eric Stanley Usher

Donald Adams Weir

George A Howells

Data transmission in, for instance, a PCM system, is effected by translation of the binary codes into ternary combinations such that to each binary code there is provided n ternary codes with the choice of the ternary code sent being dependent on secondary intelligence, such as signalling information and/or synchronization information, to be sent. In the example described a binary bit stream is split into three bit blocks each of which is converted into a three bit ternary code.

Data transmission system for transmitting primary and secondary

Intelligence is conveyed in a PCM bit stream form with alternate bits being inverted. Additional information is conveyed by violations of the alternate bit rule so that two successive bits have the same polarity. Prior to being coupled to the alternate mark inversion coder a pseudo-random bit stream is mixed by binary addition without carry to the intelligence bit stream to maintain low DC level in the transmitted mixed bit stream and to maintain bit transitions relatively high.

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Ware, United Kingdom

Eric Stanley Usher