Abstract: A method and apparatus for recording or reproducing data in which high performance encoding and a high efficiency decoding are realized to lower the decoding error rate. A magnetic recording and/or reproducing apparatus 50 includes, in a recording system, a modulation encoder 52 for modulation encoding input data in a predetermined fashion and an interleaver 53 for interleaving data supplied from the modulation encoder 52 to re-array the data sequence.

Abstract: A decoder and a decoding method can realize a high speed decoding operation without degrading the quality of decoding. The decoder comprises a path selecting section 130 for obtaining at least two or more paths showing a high likelihood out of the at least three or more paths for getting to each state and selecting the maximum likelihood path from the obtained at least two or more paths and an absolute value selecting section 160 for selecting the absolute value of the difference between the data corresponding to the maximum likelihood path and the data corresponding the second maximum likelihood path. The path selecting section 130 compares data P, Q, R, S for dimension and select the data corresponding to the maximum likelihood path by promoting an operation comparable to a tournament of competitors of the data P, Q, R, S.

Abstract: A decoder and a decoding method can perform log-sum corrections by means of linear approximation, putting stress on speed, with a reduced circuit dimension without adversely affecting the decoding performance of the circuit. The decoder comprises a linear approximation circuit 68 added to obtain log likelihoods and adapted to compute the correction term expressed in a one-dimensional function of a variable by linear approximation. The linear approximation circuit 68 computes the correction term by log-sum corrections by means of linear approximation using function F=−a|P−Q|+b, where the coefficient −a representing the gradient of the function and the coefficient b representing the intercept are expressed by a power exponent of 2.

Abstract: The present invention provides a decoder with a reduced circuit dimension without adversely affecting the decoding performance of the circuit. The decoder comprises an addition/comparison/selection circuit 60 added to give the log likelihood and adapted to compute a correction term expressed in a one-dimensional function relative to a variable and add a predetermined value to the correction term in order to provide a unified symbol for identifying the positiveness or negativeness of the log likelihood for the purpose of computing the log likelihood.

Abstract: A storage unit is provided which is capable of preventing the occurrence of readout errors even if two or more errors arise within a code, and a storage unit checking method is offered which can improve the productivity. Write data produced by BCH-encoding and compacting data s1 inputted into a flash memory, capable of correcting two errors within a code in an encoder, is written in a cell array. Data read out from the cell array 3 is error-corrected and decoded in an error correction/encoder to generate output data. In the check to be made at manufacturing (or putting on the market), examination data written in advance is successively read out by one block so that the errors within each code is counted. If the number of errors assumes 1 or less, that code is subjected to error correction, whereas the block including a code whose error number is 2 or more is treated as a defective block.

Abstract: A magnetic recording and/or reproducing apparatus which achieves high performance encoding and high efficiency decoding to lower the decoding error rate. A magnetic recording and/or reproducing apparatus 50 includes, in its recording system, an error correction coder 51 for error correction coding input data and an interleaver 52 for scrambling the sequence of data supplied from the error correction coder 51.

Abstract: A magnetic recording and/or reproducing apparatus in which the decoding error rate is to be lowered through realization of the high-performance encoding and the high efficiently decoding. To this end, a magnetic recording and/or reproducing apparatus 50 includes, in its recording system, an error correction coder 51 for error correction encoding input data, an interleaver 52 for interleaving data supplied from the error correction coder 51 for re-arraying the data sequence, a modulation encoder 53 for modulation encoding the data from the interleaver 52 in a predetermined fashion and an interleaver 54 for interleaving the data from the modulation encoder 53 for re-arraying the data sequence.

Abstract: A magnetic recording and/or reproducing apparatus performing efficient decoding to lower a decoding error rate. A magnetic recording and/or reproducing apparatus 50 includes a modulation SISO decoder 63 for modulation decoding data modulation-encoded in a predetermined fashion by a modulation coder 52. In the magnetic recording and/or reproducing apparatus 50, the modulation SISO decoder 63 is a soft input soft output (SISO) type modulation decoder fed with a soft input signal and issuing a soft output signal. The modulation SISO decoder 63 is fed with a trellis soft output signal D64 supplied from a trellis SISO decoder 62 to find a soft decision value for an error correction coding data D52 fed to the modulation coder 52 of the recording system to generate a modulated soft decision signal D65. The modulation SISO decoder 63 routes the so-generated modulated soft decision signal D65 to a downstream side error correction soft decoder 64.

Abstract: Three dual-port RAMs of the number of bits=8 and the number of words=4 are provided in a path memory circuit. Path selection information is sequentially written into the three RAMs every clock in accordance with the control of a control circuit. On the other hand, the path selection information is read out every clock from the RAMs in accordance with the control of the control circuit and is inputted as read path selection information or the like to a tracing circuit. The tracing circuit executes the tracing operation as many as three times on the basis of the read path selection information and trace starting state information which is formed by the control circuit. On the basis of a tracing result, the decoding data and a trace starting state in the subsequent clock are obtained.

Abstract: Error correction coding and decoding according to a serial concatenated modulation system are carried out under high code rate. A coding apparatus 1 comprises three convolutional coders 10, 30 and 50 for carrying out convolutional operation; two interleavers 20 and 40 for rearranging order of data input; and a multi-value mapping circuit 60 for carrying out mapping of a single point on the basis of a predetermined modulation system. The coding apparatus 1 carries out convolutional operation whose code rate is “⅔” as coding of extrinsic codes by a convolutional coder 10, and carries out convolutional operation whose code rate is “1” as coding of inner codes by a convolutional coder 50, and a multi-value modulation mapping circuit 60 applies mapping to a transmission symbol of a 8 PSK modulation system to output it as a single code transmission symbol.

Abstract: To carry out error correction coding and decoding according to a serially concatenated coded modulation system with a small circuit scale and high performance. A coding apparatus 1 is designed so that an interleaver 20 interleaves order of bits so that all weights are coded by a convolutional coder 30 with respect to data comprising a series of 3 bits supplied from a convolutional coder 10; the convolutional coder 30 makes as small as possible the total value of the hamming distance of input bit between passes to be the minimum Euclidean distance with respect to data of 3 bits supplied from the interleaver 20; and a multi-value modulation mapping circuit 40 causes the hamming distance of input bits in the convolutional coder 30 as the distance between signal point on the I/Q plane is smaller to subject data of 3 bits supplied from the convolutional coder 30 to mapping.

Abstract: A soft output decoding method and apparatus are provided for provided convolutional codes. After computing the number of states times I&bgr; (&bgr;t˜&bgr;t−D+1) for a truncated length, the soft output outside the truncated length is sequentially computed, as next following I&bgr; (&bgr;t−D˜&bgr;t−2D+1) outside the next following truncated length is computed, at the same time as I&bgr; of the next truncated length is sequentially computed. In this manner, a decoder performs computation of I&bgr; within the truncated length and computation of I&bgr; retrogressive by not less than the truncated length, in parallel processing, as a result of which the computation of I&bgr; per clock is the number of states x2. This apparatus and method thereby reduces the volume of computation and expedites the decoding.

Abstract: A polyethylene composition which has a wide molecular weight distribution and excellent balance among melt elasticity, flow characteristics and mechanical properties, and which is suitable for use in producing large-scaled hollow plastics articles. The composition comprises a higher molecular weight ethylene polymer or copolymer and a lower molecular weight ethylene polymer or copolymer which is specified in view of the content of o-dichlorobenzene and the ratio of the area under the elution temperature-eluate volume curve between 25.degree.to 90.degree. C. to the area under said curve of 90.degree. C. and above in temperature rising elution fractionation.

Abstract: A polyethylene composition which has excellent flow characteristics and mechanical properties, especially low temperature mechanical properties as well as thermal stability, elasticity and workability for molding. The polyethylene composition comprises 20 to 80 wt. % of an ethylene-.alpha.-olefin copolymer of higher molecular weight having (a) intrinsic viscosity (.eta..sub.1) of 1.2 to 9.0 dl/g, (b) density (d.sub.1) of 0.890 to 0.935 g/cm.sup.3 (c) a specific areal ratio calculated with an elution temperature-eluate volume curve in elution fractionation, and (d) a specific quantity of the content which is soluble in 25.degree. C. o-dichlorobenzene, and 80 to 20 wt. % of ethylene homopolymer or ethylene-.alpha.-olefin copolymer of lower molecular weight having (e) intrinsic viscosity (.eta..sub.2) of 0.2 to 1.6 dl/g, (f) density (d.sub.2) of 0.890 to 0.980 g/cm.sup.3 and, wherein the above (.eta..sub.1) is larger than (.eta..sub.2), and the prepared composition has an intrinsic viscosity (.eta.) of 0.

Abstract: A hydraulic system for an automatic power transmission of a motor vehicle and adapted for preventing creep of the motor vehicle when the vehicle comes to a complete halt. The hydraulic system includes a first shift valve responsive to throttle pressure and governor pressure to control supply of line pressure into servo means for actuating a friction element to provide lower gear reduction ratio, and a second shift valve responsive to released condition of an accelerator pedal of the vehicle for supplying line pressure into a governor pressure port of the first shift valve, whereby the first shift valve is moved in dependence on throttle pressure and line pressure into a position to supply line pressure into the servo means for thereby effecting shift into the lower gear reduction ratio in the power transmission.

Abstract: A valve mechanism is comprised of first and second valves, the first valve producing a first fluid pressure in dependence on engine intake manifold vacuum while the second valve produces a second fluid pressure in response to the first pressure. A first valve spool is connected at its one end to a vacuum diaphragm responsive to the engine intake manifold vacuum. A valve spool land is exposed to the second pressurized fluid so that the spool is biased in one direction by the force developed by the second pressurized fluid acting on the valve land. A second valve spool is movable in response to the first fluid pressure to a position to reduce the pressure level of the second fluid when the engine intake manifold vacuum reaches a predetermined value.

Abstract: The shift mechanism of an automotive power transmission system is locked in the neutral or parking position by a locking device which is responsive to completion or incompletion of a prescribed manipulative procedure to render a safety device such as a safety belt arrangement into a proper protective position, the locking device including a cam movable with any suitable member of the shift mechanism and a catch member which is moved into locking engagement with the cam if the prescribed manipulative steps to move the safety device into the proper protective position is incomplete.