US 5,471,486 A · 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

Abstract

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.

Claims26

Dependent claims

A method of encoding data symbols in accordance with a BCH code to obtain a code word having a code word order in which parity symbols for the code word are interposed between a first portion of the data symbols and a second portion of the data symbols, the method employing use of a shift register and comprising the steps of:

sequentially providing the data symbols to the shift register in a predetermined order in which the second portion precedes the first portion and zero data symbols are located in between the second portion and the first portion;
initially modifying each of the data symbols and zero data symbols as each is provided to the shift register based upon at least one of data symbols and zero data symbols previously provided to the shift register;
sequentially shifting the data symbols and zero data symbols, after initial modification, through the shift register in accordance with the predetermined order, and further modifying each of the data symbols and zero data symbols as each is shifted through the shift register based upon at least one of data symbols and zero data symbols later provided to the shift register to produce the parity symbols;
and
positioning the parity symbols with respect to the data symbols in accordance with the code word order so that the parity symbols are interposed between the first portion and the second portion to obtain the code word.

2 more elements

A device for encoding data symbols in accordance with a BCH code to obtain a code word having a code word order in which parity symbols for the code word are interposed between a first portion of the data symbols and a second portion of the data symbols, the device comprising:

parity determining means for (a) receiving the data symbols in a predetermined order in which the second portion precedes the first portion and zero data symbols are located in between the second portion and the first portion, and (b) producing the parity symbols therefrom, said parity determining means including
a shift register which (a) sequentially receives the data symbols and zero data symbols in accordance with the predetermined order, and initially modifies each of the data symbols and zero data symbols upon receipt based upon at least one of data symbols and zero data symbols previously received by said shift register;
and (b) sequentially shifts each of the data symbols and zero data symbols, after initial modification, through said shift register in accordance with the predetermined order, and further modifies each of the data symbols and zero data symbols as each is shifted through said shift register based upon at least one of data symbols and zero data symbols later received by said shift register to produce the parity symbols;
and
positioning means for positioning the parity symbols with respect to the data symbols so that the parity symbols are interposed between the first portion and the second portion to obtain the code word.

2 more elements

parity determining means for (a) receiving the data symbols in a predetermined order in which the first portion precedes the second portion and dummy symbols are located in between the first portion and the second portion, and (b) producing the parity symbols therefrom, said parity determining means including
a shift register which (a) sequentially receives and shifts there-through the data symbols and dummy symbols in the predetermined order to produce provisional parity symbols, and (b) backward shifts therethrough the provisional parity symbols to produce the parity symbols;
and
modification means for modifying the data symbols and dummy symbols prior to each being received by said shift register based upon at least one of data symbols and dummy symbols previously received by said shift register;
and
positioning means for positioning the parity symbols with respect to the data symbols so that the parity symbols are interposed between the first portion and the second portion to obtain the code word.

3 more elements

Dependencies are inferred from the claim text.

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

Life of this patent

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

Life of this patent

Abstract

Claims26