Abstract: The present invention relates to a method and apparatus for decoding symbols each representing a digital word including a turbo encoded bit, a parity bit and at least one uncoded bit. A first soft metric generator produces a soft metric of the encoded bit in each symbol and one or more second soft metric generators generate a soft metric of the or each uncoded bit in each symbol. A turbo decoder decodes the soft metric of the encoder bit so as to produce a hard value and a soft estimate of the encoded bit. A turbo encoder encode the hard value of the encoded bit to produce a reconstruction of the encoded bit and two parity bits. A puncture module punctures the parity bits once. One or more hard decision modules produce a hard decision for the or each uncoded bit of each symbol.

Abstract: The present invention relates to a method and apparatus for encoding input words consisting of a plurality of information bits so as to produce encoded output symbols. The invention has particular application to the production of encoded output symbols which are to be subject to phase shift key (PSK) modulation. The invention is advantageously employed in generating phase shift key modulated signals for digital television signal transmission. A turbo encoder is used to receive and encode a first portion of each input word so as to generate corresponding encoded and parity bits from the input words. A puncturing module punctures the parity bits once for each encoded bit. A mapping circuit receives an uncoded second portion of each input word and forms an output symbol for each input word from the uncoded second portion and from the corresponding encoded and punctured parity bits.

Abstract: An apparatus for producing a product code having a first dimension systematic block code of length nx elements and a second dimension systematic block code of length ny elements has a first dimension encoder 12 for receiving a data element stream 11 to produce the first dimension block code having kx data elements and nx−kx parity elements, the parity elements being derived from the data elements. The first dimension encoder is arranged to produce ky first dimension code vectors where ky is the data element length of the second dimension systematic block code. The second dimension encoder 14-16 is representative of nx encoders. The second dimension encoder receives the first dimension code vectors as they are produced and derives (nxny-nxky) parity elements for the second dimension systematic block code.