Abstract: A maximum likelihood decoding circuit is arranged to reduce power consumption through the effect of a Viterbi algorithm. A plurality of storing elements located vertically in a column and for storing each state survivor path information at the same time point are treated as storing element blocks in a manner to correspond to the combination (state) of intracode interferences. The outputs from the storing elements are again applied into the inputs of the corresponding storing elements contained in the same storing element block through path history selecting circuits. Each of the storing blocks is periodically started on the input timing of a receiving signal at each processing time point by starting signals (pointers) outputted from a starting signal (pointer) generated circuit. A storing element block output circuit and storing element block output terminals are provided in each of the storing element blocks so that a path memory circuit output may be outputted through an OR circuit.

Abstract: An information storage apparatus has a disk medium setting data recording areas along a plurality of tracks concentrically arranged, a head for recording and reproducing data on tracks of the disk medium, an actuator for moving the head to a desired track among the plurality of tracks. Also included is an electric circuit for controlling recording and reproducing in response to detecting the distance from a recorded magnetization pattern on an adjacent track in the radial direction by detecting previously recorded signals on adjacent tracks while data recording. Even if the track density is increased, the upper limit of a threshold value of a function for preventing off-track recording of the information storage apparatus can be increased and a high track density of the information storage apparatus can be easily realized.

Abstract: A digital magnetic recording/reproducing apparatus that has an LVA detector, and that is able to maintain the coding rate as high as {fraction (8/9)} or more, and record at a higher density than in the prior art, wherein, in order that the data sequences up to the (2n−1)th best sequence (n>1) are obtained in the order of higher likelihood ratios, and that. the candidates of those data sequences can be produced, the LVA detector has provided therein a unit which replaces the likelihood ratio and path memory of the ith best sequence by those of the (2i−1)th best sequence when the contents of the (i−1)th path memory coincide with those of the ith path memory (i=2, 3, . . .

Abstract: A digital magnetic recording/reproducing apparatus includes an LVA (List Viterbi Algorithm) detector which produces first to nth best sequences (n>1) of a decoded result, and replaces a likelihood ratio and a path memory of the ith best sequence (i=2, 3, . . . , n) with those of the (2i−1)th best sequence when contents of path memories of the (i−1)th and ith best sequences are equal to each other and an absolute value of a difference between likelihood ratios of the (i−1)th and (2i−1)th best sequences is smaller than a decision threshold. Alternatively, the LVA detector initializes a likelihood ratio of the ith best sequence to be a likelihood ratio of the (i−1)th best sequence with a constant difference value added thereto when contents of path memories of the (i−1)th and ith best sequences are equal to each other.

Abstract: When the amount of position error PE of a magnetic head meets the condition of Ewf>PE>=Eww for two threshold values Ewf and Eww meeting Ewf>Eww, the track is registered in the track information table as a track requiring rewrite and the tracks on both sides neighboring to the track are temporarily write-inhibited. The data of the track is rewritten on another track later so as to maintain the data. By doing this, the offtrack of the recording track can be made smaller without sacrifice of the access speed and the occurrence probability of write fault can be reduced. Furthermore, the reliability of a magnetic disk apparatus can be improved.

Abstract: A magnetic storage apparatus is provided with unit for identifying the frequency of overwriting storage at the time of overwriting in the same data sector, and depending on the frequency of overwriting, a code for coding or a scrambler initial value is changed at every overwrite operation. The modulation code has the same code rate so that a data length does not change at every write operation. A number corresponding to the present modulation code of each data sector is stored on a memory, and the aforesaid number is also written as an additional bit in the data sector on a medium. Data are read only when the modulation coding number on the memory and the modulation coding number on the medium, which are compared, agree with each other. If they do not agree, offset reading is performed until they agree, and then the read operation is performed.

Abstract: A digital write-and-read method and a signal processing apparatus wherein a write encoder includes a bit distribution circuit for dividing an input data block into n (n: 2 or more) series of bit strings and outputting them in parallel, a first coding circuit for executing predetermined coding for each of data series so distributed and a second coding circuit for converting the output bit series D1 to D3 of the first coding circuit to an n-bit channel code by looking up the previous channel code information, and wherein the second coding circuit executes coding by using a combination having a large Euclidean distance in a partial response equalization output taking inter-symbol interference of at least three bits into consideration as a pair.

Abstract: A decision feedback equalization circuit which can be operated at a high speed with a low cost as well as a high-speed digital data communication system and a high-speed digital data recording system using the equalization circuit are disclosed. The decision feedback equalization circuit has data memories which correspond to the number of available values in decision result and in which feedback signals corresponding to all the next decision results are previously prepared as candidates so that a suitable one of the feedback signal candidates is selected and fed back based on the obtained decision result, thus realizing high-speed operation of a feedback loop.

Abstract: A magnetic recording apparatus comprises: a magnetic recording medium for recording a binary signal; a magnetic head for detecting the binary signal; an amplifier for amplifying the binary signal detected by the magnetic head; a channel for outputting the amplifier binary signal in the form of a timing value sequence, the timing value sequence alternately providing positive and negative peak values following the rule of the binary signal a recorded in the recording medium; a temporary judging unit for judging a presently input timing value of the timing value sequence supplied from the channel as one of the positive peak value, the negative peak value, and an intermediate value, in accordance with the relationship with a preceding timing value temporarily judged as one of the positive and negative peak values; a final judging unit for finally setting the preceding timing value as one of the positive and negative peak values and the intermediate value, in accordance with the relationship with the presently inp

Abstract: A magnetic recording/reproducing uses a wide frequency band of a DC component to the next lowest spectral null frequency point and higher by using an existing recording/reproducing head and medium. Intersymbol interference is added to a magnetic recording channel so that an impulse response comes to a partial-response channel shown by polynomial 1-D.sup.n (D.sup.n is an n-bit signal delay); in which T is a Nyquist interval (reproduction-bit time interval), the values of (n>2) and T are selected by assuming equal frequency interval between the spectral null frequency points 1/nT, and thereby a symbol string having a Nyquist frequency equal to or higher than the second spectral null frequency point from the lowest frequency side excluding the vicinity of the DC component of the recording/reproducing characteristic is recorded or reproduced.

Abstract: A signal processing apparatus for converting an analog signal to a digital signal and processing the digital signal. In particular, a digital filter for performing processing at high speed is implemented by using an integrated circuit of low power consumption. The signal processing apparatus includes a circuit for comparing an input analog signal with each voltage of a plurality of analog reference voltages and generating a thermometer code Tc depending upon the analog input signal, a decoder for detecting a change point of the thermometer code Tc, and a plurality of memory circuits having output signal lines of the decoder as word selection lines. The product of an input signal value corresponding to each word selection line and a predetermined filter coefficient is stored in the corresponding word of the memory circuits. The memories are used as look-up tables.

Abstract: In a phase discrimination signal processing system in the signal reproduction of a magnetic recording and reproducing apparatus, instead of differentiation of a reproduced signal, amplitude discrimination automatic equalization is effected for an isolated waveform at a phase discrimination point corresponding to an isolated magnetization reversal reproduced by a magnetic head such that an amplitude at each discrimination time other than a peak point is zero to effect phase discrimination of the signal waveform.

Abstract: A nonlinear compensation A/D converting method and a circuit for compensating asymmetry of a reproduction signal waveform, so as not to deteriorate the performance of a discriminator even if there is a nonlinearity such that the amplitudes of the signal differ in dependence on the polarities of the waveforms like a reproduction waveform of an MR head are provided. Scales 1+ and 1- of an A/D converter are set to values which differ in dependence on the positive and negative polarities of the input signal, so that a nonlinear compensation which is suitable for a high accurate and high speed operation can be realized. Even an MR head in which the asymmetry between the upper and lower waveforms of the reproduction waveform is large can be used. A yield of the head can be improved.

Abstract: A reproduction signal processing apparatus includes a memory circuit storing a predetermined pattern for deciding equalizing characteristics of an automatic equalizer in response to variation of a reproduction signal, a pattern converting circuit for converting the predetermined pattern outputted from the memory circuit into an equalization target pattern serving as a target of the equalization and correction by the automatic equalizer, an equalization error calculating circuit for producing an equalization error from the equalization target pattern and the equalization signal outputted from the automatic equalizer, and the automatic equalizer executing a partial response waveform process of the reproduction signal on the basis of the equalization error, for correcting the predetermined equalizing characteristics of the automatic equalizer by tracing the fluctuation of the reproduction signal.

Abstract: A magnetic recording apparatus includes a magnetic recording medium for recording a binary signal; a magnetic head for detecting the binary signal; an amplifier for amplifying the binary signal detected by the magnetic head; a channel for outputting the amplified binary signal in the form of a timing value sequence, the timing value sequence alternatively providing positive and negative peak values following the rule of the binary signal that recorded in the recording medium; a temporary judging unit for judging a presently input timing value of the timing value sequence supplied from the channel as one of the positive peak value, in accordance with the relationship with a preceding timing value temporarily judged as one of the positive and negative peak values; a final judging unit for finally setting the preceding timing value as one of the positive and negative peak values and the intermediate value, in accordance with the relationship with the presently input and temporarily judged timing value; a counter

Abstract: A magnetic recording data storage system includes a magnetic recording medium having pits formed therein, the pits defining recording tracks on the magnetic recording medium and being arranged in a staggered manner relative to respective center lines of the recording tracks, a magnetic head including an inductive element for recording data on the recording tracks and a magnetoresistive element for reproducing data from the recording tracks, one of (1) a unit for magnetically producing a signal from the pits, and (2) an optical unit for optically producing a signal from the pits, the optical unit including a laser for illuminating the pits, servo means for positioning the head on the recording tracks based on the signal produced from the pits, the servo means including a dual-stage actuator including a rough movement portion and a fine movement portion.

Abstract: The time interval/amplitude level difference between sequential peaks in waveforms of first reproducing signals from a recording medium is detected and stored in a storage. The time interval/amplitude level difference between peaks in a waveform of a second reproducing signal from the recording medium is detected and compared with the time interval/amplitude level difference stored in the storage to thereby perform peak detection in the waveforms thereof. An original bit train of the first reproducing signal corresponding to a maximum-likelihood waveform selected among the waveforms of the first reproducing signals is given as a standardized signal. Data are provided to represent the time interval/amplitude level difference between the sequential peaks in the waveforms of the reproducing signals in a range of electromagnetic signal interference on the recording medium.