Abstract: Errors in a first data signal of a first error correction code system in a reproduced signal are corrected to get first correction-resultant data. Errors in a second data signal of a second error correction code system in the reproduced signal are corrected to get second correction-resultant data. All address information pieces in the second correction-resultant data for every error correction block are subjected to error checks. When at least one of all the address information pieces is correct, a descramble initial value is set in response to the correct address information piece. When all the address information pieces are erroneous, a correct address information piece is estimated from an address information piece associated with a previous error correction block and the descramble initial value is set in response to the estimated correct address information piece. The first correction-resultant data are descrambled in response to the descramble initial value.

Abstract: Errors in a first data signal of a first error correction code system in a reproduced signal are corrected to get first correction-resultant data. Errors in a second data signal of a second error correction code system in the reproduced signal are corrected to get second correction-resultant data. All address information pieces in the second correction-resultant data for every error correction block are subjected to error checks. When at least one of all the address information pieces is correct, a descramble initial value is set in response to the correct address information piece. When all the address information pieces are erroneous, a correct address information piece is estimated from an address information piece associated with a previous error correction block and the descramble initial value is set in response to the estimated correct address information piece. The first correction-resultant data are descrambled in response to the descramble initial value.

Abstract: A DSV (Digital Sum Value) control system for use in conversion of a sequence of m-bit digital data codes into at least first and second sequences of n-bit digital modulation codes using a plurality of modulation tables under the DVD (Digital Video Disc) standards, for example. The DSV control system outputs a sequence of modulation codes produced by selecting, in time sequence, one of the codes of the first sequence or one of the codes of the second sequence according to a select signal SB. The select signal SB is provided based on a DSV control enable flag indicating that DSV control enable codes of the first and second sequences will appear at a following address and a select signal SA indicating which of the DSV control enable codes of the first and second sequences should be selected in order to optimize a DSV of the outputted sequence of modulation codes.

Abstract: Digital modulating method and apparatus are provided which converts m-bit data codes, in sequence, into digital modulation codes each consisting of n channel bits (n>m) to form a modulation code sequence using connection codes. Bit patterns of portions of the modulation code sequence and the connection codes are changed or additional bit patterns are inserted into the modulation code sequence so as to meet given conditions of a minimum transition interval, a maximum transition interval, and a Digital Sum Value. Demodulating method and apparatus performing a reverse modulation operation are also described.

Abstract: An optical disk has regions in which sync signals are recorded. A data detection circuit detects data from a reproduced signal at a timing determined by a data detecting signal. A reproduced waveform of each sync signal is sampled at a first time point, and a first sample value representative thereof is generated. The reproduced waveform of each sync signal is sampled at a second time point different from the first time point, and a second sample value representative thereof is generated. The first and second sample values are compared, and a comparison signal representing a result of the comparing is generated. A phase of the data detecting signal is controlled in response to the comparison signal.

Abstract: In an apparatus for recording/reproducing data on a disc along a spiral track, a track-turn position of a record/reproduce head is changed in response to a kick back signal determined by a value of the register and read/write error signal just after a sector pulse or an address signal in addition to the conventional access command which changes the track-turn position through calculation from address included in the access command and the present address. The change of the track-turn position by the kick back signal makes access time shorter than that which would be done by the conventional access command. Moreover, in such apparatus, execution of the kick back operation is determined at every N sectors, wherein N=M-[T1/T2], where M is the number of sectors of one track turn; T1 is a time interval necessary for changing the record/reproduce head by one track-turn back; T2 is an interval necessary for scanning one sector by the record/reproduce head; and [T1/T2] shows a least natural number more than T1/T2.

Abstract: An optical recording/reproducing system for optically recording and reproducing an information signal on and from an optical disc (31) to be recorded with a plurality of track turns includes a light source (52); an optical head (45b) carrying an objective lens (62) for directing a light beam from the light source (52) to one of the track turns, and a tracking servo actuator for displacing the light beam within a movable range to perform both track feed and tracking servo operations for one of the track turns; the optical head (45b) being stationary with respect to the optical disc (31) while performing the track feed and tracking save operations by displacing the light beam in a radial direction of the optical disc; and a recording area on the optical disc having a radial distance equal to or smaller than the movable range of the tracking servo actuator.

Abstract: A rotary head type digital signal recording and reproducing apparatus plays a magnetic tape which is pre-recorded with a time division multiplexed audio signal comprising a PCM audio data and a sub-channel signal which is time division multiplexed immediately before and after the PCM audio data for each track. When carrying out an after recording of the sub-channel signal to be reproduced in a half tape speed mode, both of the rotational speed of the two magnetic heads and the tape transport speed are set identical to those at a standard tape speed mode which has a rotational speed and the tape transport speed which are twice those of the half-speed mode.

Abstract: A data recording and reproducing apparatus promotes error-free and speedy exchange of data between separate recording media. When desired primary data is to be recorded on a master recording medium, secondary data is added to the primary data in order to detect and correct data errors. The primary and secondary data are recorded on the master recording medium in a plurality of series which differ in recording sequence from each other. The primary data is reproduced from the master recording medium together with the secondary data for the different series at the same time, regardless of their recording sequences. The reproduced primary data is allowed for error check and correction based on the secondary data and is recorded in the slave recording medium.

Abstract: A method and apparatus for digital magnetic recording of data in which digital data is recorded on a magnetic recording medium after being demodulated by the NRZI (Non-Return-to-Zero Inverted) system and read thereoutof timed to magnetic flux reversal caused by the recorded data on the recording medium. The digital data is encoded in a predetermined manner before the NRZI modulation so that at least part of "false" bits contained in the digital data is converted into "true" bits, resulting in an increase in the number of "true" bits. The encoded data is written into the recording medium after the NRZI modulation. In the event of reproduction of the data from the recording medium, self-clocking occurs to generate a data readout timing. The increased number of "true" bits insures desirable self-clocking. The data read from the recording medium is decoded to the original digital data.

Abstract: In a circuit arrangement for magnetic recording apparatus having a multi-track head, a resistor network is provided so that each operational amplifier associated with each magnetic head included in the multi-track head functions as a constant-current circuit. The resistances of four resistors in the resistor network are selected so that no current flows via one resistor interposed between the output terminal of the operational amplifier and a terminal of the head in receipt of no input signal even if leakage flux emitted from adjacent head is picked up by the head. Therefore, undesirable influence due to crosstalk can be effectively prevented, providing high quality reproduction in the case of audio signal recording or low bit error rate in the case of digital recording.

Abstract: A data reproducing apparatus for reproducing data recorded on multi-tracks, comprises a signal transducer for simultaneously reproducing pre-recorded frame signals from a plurality of tracks on a recording medium, a write-in address generating circuit provided in each of transmission systems for reproduced signals from the tracks obtained in parallel from the signal transducer, for generating a write-in address indicating the number of bits of data within one frame signal from a counter which counts clock pulses having a period equal to the transmission bit rate, a memory into which data within frame signals reproduced from the tracks are written and then read out, and a memory control circuit for controlling the memory so as to successively and recursively apply the data within the frame signals reproduced from the tracks and write in the data at the write-in addresses obtained from the write-in address generating circuit, and read out the written-in data from the memory with the timing arranged after a pred

Abstract: A multichannel record disc recording system uses two channels of direct wave sum signals and two channels of angle-modulated wave difference signals which are multiplexed and recorded in one sound groove on a record disc. During recording, a tracing distortion compensation means imparts a reverse distortion which cancels the tracing distortion produced, with respect to the sum signals, during reproducing. Since the compensation means is in the transmission paths of the direct wave sum signals, the reverse distortion is only imparted to the direct wave sum signals. Also, phase correction signals are provided.

Abstract: A multichannel record disc recording system comprises: a circuit for shaping sum and difference signals from multichannel signals, angle modulating the difference signal, multiplexing the sum signal and the angle-modulated difference signal, and recording the resulting signal on a record disc. A first level control circuit, in the transmission system for the sum signal, operates to attenuate the high-frequency band of components of the sum signal when its level is at a high level. A second level control circuit, in the transmission system of the difference signal, operates to attenuate the middle-high frequency band of components of the difference signal when its level is at a high level. The first level control circuit attenuates the level of the sum signal to prevent an admixing of the higher harmonics of the high frequency component of the sum signal into the band of the angle-modulated difference signal.

Abstract: A signal frequency band control system comprises an amplifier for amplifying an input signal. A first differentiation or integration circuit receives an output signal from the amplifier and carries out a primary differentiation or primary integration. A second differentiation or integration circuit is supplied with an output signal from the amplifier and carries out a secondary differentiation or secondary integration. A first gain constant circuit multiplies the output signal from the second differentiation or integration circuit by a first gain constant. A second constant circuit multiplies, by a second gain constant, the signal resulting from the addition of the output signal of the first differentiation or integration circuit and the output signal of the first gain constant circuit. A circuit negatively feeds back, to the amplifier, a signal resulting from the addition of the output signal of the amplifier and the output signal of the second gain constant circuit.

Abstract: An improved finely pulverized expansive cement additive which causes the cement mortar or concrete mixed therewith to bear increased chemical prestressing property, the clinker of said additive substantially consisting of alite crystals containing fine crystals of calcium oxide therein and a phase substantially consisting of optic-microscopically amorphous calcium sulfate in which said alite crystals are dispersed.