U.S. Philips Corporation

Erik W Gaal

Constant P Baggen

Cornelis M Van Uijen

Johannes J Verboom

Methods and devices for encoding data symbols in accordance with a BCH code to obtain a code word in which parity symbols are located in the middle of the code word. The data symbols are supplied to a parity determining device in a predetermined order to produce the parity symbols, which parity determining device either employs a shift register or a shift register bank. When the parity determining device employs a shift register, depending upon the predetermined order in which the data symbols are supplied to the shift register, the data symbols are either (a) forward shifted through the shift register, after each data symbol has been initially modified on the basis of previously supplied data symbols, and further modified as each is being shifted through the shift register on the basis of subsequently received data symbols so as to produce the parity symbols or (b) forward shifted through the shift register, after each data symbol has been modified on the basis of previously supplied data symbols, so as to produce provisional parity symbols which are, in turn, backward shifted through the shift register to produce the parity symbols. Once the parity symbols have been produced, they are positioned among the data symbols so as to produce the code word.

Methods and devices for encoding data symbols in accordance with a BCH

A method is revealed for recording an information signal (Vi) on a record carrier (1). The information signal (Vi) is converted into code words (200), which comprise a variable number of bits of a first logic value ('1') and a variable number of bits of a second logic value ('0'). The number of successive bits of the first logic value ('1') is at least equal to P. The number of successive bits of the second logic value, situated between the bits of the first logic value, is at least equal to Q, Q being greater than P. A pattern of recording marks (8;54) corresponding to the code signal (Vc) is recorded on the record carrier (1) in such a way that bits of the first logic value ('1') are represented by recording marks (8;54). Moreover, an information recording device (FIG. 17), an information read device, and a decoding device (FIG. 18) are revealed.

Method of and device for recording information, record carrier, device

A method of and device for recording an information signal (Vc) on a record carrier (1) are revealed. The information words of the information signal are converted into code words (200) comprising a variable number of bits of a first logic value ('1'). The number of consecutive bits of the first logic value is at least equal to P. the number of consecutive bits of the second logic value ('0') is at least Q, P being an integer greater than or equal to 1 and Q being an integer greater than P. the code words are selected in such a way that for information words of successive values the associated code words differ for only one bit. During recording an elementary mark (54) is formed on the record carrier for every bit of the first logic value. Moreover a read device for the record carrier thus obtained is described.

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Eindhoven, Netherlands

Erik W Gaal