Abstract: Extended error protected communication system.An extended consumer communication system uses a signal that is error protected by a block code. The generator polynomial isG.sub.n (x)=g.sub.o (x) . . . g.sub.n (x)which is factorizable, and each of the factors implement a linear and systematic code. Generally, each of the factors adds redundancy and raises the level of error protection. In this way, redundancy that is associated to a later term of the sequence occupies code positions that are protected by at least one earlier term in the sequence and may in consequence be used for positioning data that is protected by such earlier term, upon surrender of such higher protection level.

Abstract: Receiver for receiving a transmission signal comprising N frequency multiplexed data modulated carriers, having a good compromise between insensitivity to multipath reception and receiver complexity, and which may enable a reduction in transmission bandwidth and transmitter power. In such a receiver, modulation signals of the carriers are supplied by a frequency multiplex demodulator to a symbol detection device via an equalizer device. The equalizer device compensates distortion in the modulation signals supplied thereto, such that the symbol detection device may detect the transmitted data with reduced error probability. When the transmission signal reaches the receiver with different delay times, this distortion is mainly a kind of cross-talk between the modulation of adjacent carriers. Therefore substantial compensation is achieved by combining the modulation signal of a carder with signals representative of the data of the adjacent carriers.

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.

Abstract: The invention relates to a method of transmitting data by modulating a frequency multiplex of carriers at a relatively low symbol rate, such as in OFDM (orthogonal frequency division multiplex). According to the inventive method, intersymbol interference is deliberately introduced at the transmitter side to reduce cross-talk between data of different carriers at the receiver side, such as to simplify an equalizing device in a receiver. The intersymbol interference at the transmitter side is introduced after the frequency multiplex modulation has taken place, by repeating groups of output symbols produced by an IFFT transformer and subsequently shaping these repeated groups by means of symbol-by-symbol scaling with coefficients constituting a window function. Subsequent shaped and repeated groups of these output symbols mutually overlap.

Abstract: An extended television signal comprises control data for controlling an extended television decoder. The control data comprise first information bits (NB) for conveying information which need not be very reliably decodable immediately upon switching between broadcast channels or when their contents have changed. Each first information bit (NB) is channel-encoded by means of a first DC-free channel code into first channel bits each having a first duration (2 Tc). The control data further comprise second information bits (LB) for conveying information which must be very reliably decodable immediately upon switching between broadcast channels or when their contents have changed. Each second information bit (LB) is channel-encoded by means of a second DC-free channel code into second channel bits which each have a second duration (10 Tc) exceeding the first duration (2 Tc).

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: 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.

Abstract: A description is given of a semiconductor memory with an on-chip error correction facility. The code used is defined over the location domain of the columns. The columns are arranged in patterns of non-redundant and redundant memory cells which recur with a fixed period. As a result of the convolution code chosen, decoding is possible by way of a small number of series connected gates, so that the time delay is limited. The correction capability of the code is only partly used because complete use could cause additional delay.

Abstract: Information is transmitted by a digital audio transmission line, which may include recording and playback from a digital audio disc, that includes information other than conventional two-channel audio signals and in which error correction of the data transmitted in either direction between a user and a medium is provided. Information integrity is maintained by a first and second cross-interleave Reed-Solomon code (CIRC), in which a third Reed-Solomon code is overlaid on the CIRC code, whereby a sector is built from user words and protected by a quasi-product code, and then an encoded sector is divided into groups, which are group-wise presented to the CIRC encoder.

Abstract: 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.

Abstract: A block of code symbols is protected by a product code or a pseudo product code. First of all, all syndrome symbols are formed and all code words having a syndrome which deviates from zero are provided with a flag. Each non-redundant symbol forms part of a first code word and also of a second code word, the numbers of flags of first and second code words being separately summed. The code words are successively addressed and an error location is determined. When an error location forms part of an incorrect first code word as well as of an incorrect second code word, it is corrected; if the second code word is not signalled as being incorrect, however, the error will not be corrected. After correction, the syndromes are updated, the flags being updated and the summing results being decremented only if the syndromes of both relevant code words are zero. In the opposite case the flags will remain unmodified for the time being.

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: Information is transmitted by a digital audio transmission line, which may include recording and play back from a digital audio disc, that includes information other than conventional two channel audio signals and error correction of the data transmitted in either direction between a user and a medium is provided. Information integrity is maintained by a first and second cross-interleave Reed-Solomon code (CIRC), in which a third Reed-Solomon code is overlaid on the CIRC code, whereby a sector is built from users words and protected by a quasi-product code, and then an encoded sector is divided into groups, which are group-wise presented to the CIRC encoder.

Abstract: During the decoding of channel symbols included in multi-symbol code words in a data stream which is protected by a multi-symbol error correcting code such as a Reed-Solomon code, all channel symbols are first demodulated to derive the corresponding code symbols and a first indicator flag indicates whether or not the demodulation is reliable. All code symbols of a code word are subsequently collected, after which decoding is commenced to decode such code symbols and if correction of incorrect symbols of a code word is possible the code word is corrected. The decoding reliability of the corrected code word is indicated by a second indicator flag. If the corrected code word is unreliable, the stream of channel symbols is addressed again. During the latter operation, only the unreliably demodulated code symbols are replaced by new code symbols in order to enable renewed decoding of the code word.

Abstract: A method for storing and reproducing data by means of a standard compact-disk digital audio player. The bit groups in which the data words are contained are recorded at least three times, the analog output signal of the player being sampled and digitized during reproduction.

Abstract: A decoding system for code words which are protected against the occurrence of a plurality of symbol errors within a code word by means of a Reed-Solomon code. After the formation of the syndrome symbols, the key equation is solved, assuming the least possible number of symbol errors. When a plausible number L is found using 2L syndrome symbols, an additional number of syndrome symbols is considered for determining the discrepancy quantity. The locator equation is directly solved when it is of a low order. For a higher order, a Chien search cycle is performed and any symbol error found is removed by division until the order becomes low enough for direct solution. The decoding system is suitable for implementation by means of a microcomputer and for use in a reading device for optically readable record carriers.

Abstract: A compact-disc-digital-audio player may be adapted to read optical audio discs in which digital information is stored by controlling the time-base correction circuit in this player by means of a clock signal whose frequency is not a constant reference frequency but a frequency which is locked to the time base of the signal being read. As a result of this both the data signal and the subcode will have the same time base without the necessity of modifying the integrate circuits available for the compact-disc digital-audio player.

Abstract: A description is given of an error-correcting method for the transmission of word-wise organized data and devices for performing the method. The data words are group-wise received and some redundant words (114) of an error-detecting code are added to each group so that a first number of words is obtained, which is applied to a further encoder in two versions (118,121) having the same data content; these versions, however, are separated from one another in time over a given distance. Subsequently, a first series of check words of a first error-correcting code is added to a first group of words. The group of words and the associated check words are interleaved among as many second numbers of words. Subsequently, a second series of check words of a second error-correcting code is added to every second number of words.

Abstract: Information is transmitted by a digital audio transmission line, which may include recording and play back from a digital audio disc, that includes information other than conventional two channel audio signals and error correction of the data transmitted in either direction between a user and a medium is provided. Information integrity is maintained by a first and second cross-interleave Reed-Solomon code (CIRC), in which a third Reed-Solomon code is overlaid on the CIRC code, whereby a sector is built from users words and protected by a quasi-product code, and then an encoded sector is divided into groups, which are group-wise presented to the CIRC encoder.