TRANSMITTER AND RECEIVER APPARATUS, METHOD FOR TRANSMITTING AND METHOD FOR RECEIVING AND RECORD CARRIER OBTAINED BY THE METHOD OR THE TRANSMITTER APPARATUS

摘要

A transmitter apparatus for transmitting a digital data signal via a transmission medium (10) comprises error protection encoding means (3) for carrying out an error protection encoding on the digital data signal so as to obtain an error protection encoded digital data signal, and channel encoding means (6) for converting the error protection encoded digital data signal processed into a channel encoded digital data signal. The channel encoded digital data signal is supplied to the transmission medium. The error protection encoding means (3) is adapted to carry out an error protection encoding step on packets of p m-bit digital words in the digital data signal, and for supplying error protection encoded packets (Q) of n m-bit digital words to an output, where n, m and p are integers larger than 1, and n > p. The channel encoding means (6) is adapted to convert the error protection encoded packets of n digital words into converted packets (CP, CP') of digital words to form the channel encoded digital data signal and has generator means (60) for supplying a fixed auxiliary packet (Qf) also having the length of n digital words. The channel encoding means further comprises calculation means (58, 66) for calculating in a Galois field GF(2) a converted digital word CWi in accordance with the formula DWi + alpha .FWi, where DWi is the binary value corresponding to the i-th digital word in the packet (Q), FWi is the fixed binary value corresponding to the i-th digital word in the fixed auxiliary packet (Qf), and CWi is the binary value of the i-th converted digital word in the converted packet (CP, CP') of digital words, where i is an integer value running from 1 to n, the channel encoding means further comprising digital sum value determining means (101) for determining the digital sum value of at least a converted packet (CP, CP') in the serial datastream of the sequence of converted packets of digital words that form the channel encoded digital data signal, the calculation means being further adapted to determine a value alpha def for each packet of digital words converted into a converted packet of digital words, the channel encoding means being further adapted to combine alpha def with the converted digital words CWi obtained by the Galois field GF(2) calculation of DWi + alpha def.FWi, so as to obtain said converted packet (CP, CP') of digital words, the value alpha def for alpha being such that a running digital sum value of the serial datastream of the converted packets shows a desired pattern as a function of time.