Abstract: A method and apparatus for decoding code words which are error protected by a non-binary BCH-code against at least one symbol error. Upon reception of an input code word a syndrome information thereof is generated under control of code defining information. From the syndrome information, a key equation is set up and solved for generating an error locator polynomial sig (z) and an error evaluator polynomial w(z). On the basis of the polynomial sig (z) and its formal derivative polynomial sig' (z), Euclid's algorithm is employed to calculate two accessory polynomials b(z), c(z), such that b(z)sig(z)+c(z)sig'(z)=1. From these, a Lagrangian polynomial L(z) is calculated which for any inversed error location value has the associated error symbol value. The error data is then calculated by evaluating the error locator polynomial and the Lagrangian polynomial.

Abstract: The values of incorrect samples of, for example, a digital audio signal are estimated by means of interpolation. For this purpose an appropriate sampling interval is determined from the number of incorrect samples, in which interval the incorrect samples are situated. Subsequently, a best-fitting recursion formula is determined from the values of the samples, a first estimate being taken for the values of the incorrect samples. By means of this recursion formula the value of a sample is expressed as a weighted sum of the values of a number of preceding samples and an error term. By means of the recursion formula thus found the values of the incorrect samples are subsequently estimated, in such a manner that they are best-fitting values for the recursion formula. The Application also discloses a device for carrying out the method.

Abstract: For the decoding of a data stream which is word-wise protected against errors by a double Reed-Solomon code with symbol-wise interleaving over the code words, first the reliability information for the constituent symbols is aggregated for a code word. Therefrom the strategy is determined, entailing the number of erase symbols and the maximum number of error symbols to be corrected. The correction result is compared with a reliability code and on the basis thereof all symbols obtain an at least trivalent secondary reliability indication for decoding in the second code.

Abstract: For an error correction method for the transfer of word-wise arranged data, two word correction codes are used successively, each code acting on a group of words while, therebetween, an interleaving step is performed. The actual transfer takes place by means of channel words for which purpose there are provided a modulator and a demodulator. Invalid channel words are provided with an invalidity bit in the demodulator. During the (possibly correcting) reproduction of the data words, the invalidity bits can be used in one of the two error corrections in various ways:(a) When too many words of a group of code words are invalid, all words of the relevant group are invalidated;(b) If a word comprising an invalidity bit is not corrected during correction by means of a syndrome variable, all words of the relevant group are invalidated;(c) If the number of invalidity bits lies within given limits, they act as error locators so that the code is capable of correcting a larger number of words.

Abstract: A description is given of a system for communication between a transmitting station (30) and a receiving station (33) by way of a message which consists of a direct succession of a number of identical code words. Each message uses only a comparatively small part of the capacity of the message channel. Each code word has at least a predetermined minimum Hamming distance with respect to any other code word, including the cyclic transpositions of the latter code word. Therefore, for the detection and reproduction of a code word it is not necessary to realize word synchronization and a given category of errors can still be detected and/or corrected. The code words may concern, for example, a transmitter or program identification in a broadcasting system or a paging code for a receiving station in a system comprising selectively addressable receiving stations as in a paging system.

Abstract: Community antenna television arrangement for the reception and distribution of TV signals and digital audio signals, in particular signals which are transmitted per satellite, including a head-end connected to a receiving antenna and a signal distribution network, a time-division multiplex signal which comprises the digital audio signals in a time-multiplex distribution, being applied to the head-end, which time-division multiplex signal is modulated on a sound carrier, the bit rate of the digital audio signals to be distributed being reduced in the head-end of the community antenna television arrangement by a TDM/FDM conversion in order to reduce signal echoes.

Abstract: For an error correction method for the transfer of word-wise arranged data, two word correction codes are successively used, each code acting on a group of words while therebetween an interleaving step is performed. The actual transfer takes place by means of channel words for which purpose there are provided a modulator and a demodulator. Invalid channel words are provided with an invalidity bit in the demodulator. During the (possibly correcting) reproduction of the data words, the invalidity bits can be used in one of the two error corrections in various ways. When too many words of a group of code words are invalid, all words of the relevant group are invalidated. If a word comprising an invalidity bit is not corrected during correction by means of a syndrome variable, all words of the relevant group are invalidated. If the number of invalidity bits lies within given limits, they act as error locators so that the code is capable of correcting a larger number of words.

Abstract: An error correcting encoding and decoding system for transmission and reception of digital data is arranged for high error-correcting ability of both burst errors and random errors. In encoding apparatus a digital signal is processed as a plurality of word sequences. The words are interleaved into a different arranging order and are subjected to different relative amounts of delay. Then, first check words are generated to satisfy a parity detection matrix, such as a Reed-Solomon code matrix. After this, the resulting data words and first check words are again interleaved and are provided with respective different amounts of delay. Then, second check words are generated to satisfy a similar matrix. Finally, the first and second check words and the data words are interleaved prior to transmission.

Abstract: A sequence of k-tuples of information elements is converted by means of an error-correcting convolutional code into a sequence of n-tuples (n greater than k) of code elements. In the processing of the code elements use is made of first of all a syndrome former to form a sequence of (n-k)-tuples of syndrome elements from the n-received sequence of n-tuples of code elements. From a segment of a number of successive (n-k)-tuples of syndrome elements one or more correction bits are formed in each case so as to be able to correct the received code bits and also, if a correction is applied, to be able to update a number of further syndrome bits from that same segment. Furthermore an (n-k)-tuple of secondary syndrome bits or residue bits is formed in each case from this updated segment. A first value of such an (n-k)-tuple indicates the state in which the decoder must be provisionally considered as having corrected all errors in a predetermined sequence of n-tuples of code elements.