GB1175866A - Error detection and correction equipment - Google Patents

Abstract

1,175,866. Digital transmission systems. STANDARD TELEPHONES & CABLES Ltd. 30 May, 1968 [6 June, 1967], No. 26061/67. Heading H4P. To reduce the effects of error bursts the bits of a group of digital data words, each consisting of a multi-bit character and a corresponding error-correcting multi-bit check signal, are rearranged so that no two adjacent input bits are adjacent when transmitted. As described, the words consist of 5-bit characters and 5-bit check signals. Five such words are passed to a 50-bit shift register which has each stage connected via a gate to a corresponding stage of a second 50-bit register. The interconnection is such that when the second register is read out for transmission all the first bits of the 5-bit characters are transmitted first, followed by the first bits of the 5-bit check signals. Then the second bits of the characters and check signals are sent, then the third, and so on. This ensures that any error burst less than 6 bits long will not effect more than one bit in any one character or check signal, the check signal being such that single bit errors can be corrected. At the receiver the transmitted signals are reformed to their original order by apparatus similar to that at the transmitter.