Abstract: The linear range of a servo system for a magnetic storage device using a compared amplitude burst servo pattern and a magneto resistive (MR) sensor is enhanced by reversing the bias current. With the servo bursts displaced to opposite sides of the track centerline, the bias current is reversed to have the read function occur when the sensor is electrically biased to present the higher gain, more uniform end portion of the readback sensitivity profile at the side of the track at which the burst is written. Reversing the bias current in an MR sensor causes the readback sensitivity profile to be mirrored about the sensor center enabling the more uniform portion of the sensor response to be used to sense the respective servo pattern bursts. Where differences occur in MR gain between bias current directions, normalization or other correction is provided to compensate for variation in sensor gain.

Abstract: An apparatus for correcting header information includes a transducer for reading and writing encoded information to a magnetic storage medium. A serial/deserializer provides a deserialized output. Header information from the deserializer is stored in a header storage register. The deserialized header information is also provided to a header error correction circuit. The header error correction circuit provides an output indicating location and value of errors in the header memory. This information is used to correct errors in the header memory. The corrected header information is compared with predetermined header information and used to determine whether subsequent data associated with the header should be written to or read from the magnetic storage medium.

Abstract: An automatic gain controlling circuit is associated with magnetic heads for recording and reproducing pieces of video data information on a magnetic tape, and an in-phase current component is eliminated from a recording current flowing into one of the magnetic heads through a differential amplification between two input voltage levels produced from the recording current with the in-phase current component so that a gain control voltage signal is free from a relative accuracy between circuit components causative of the in-phase current component.

Abstract: A preamplifier configured for connection to a magnetoresistive transducer makes use of a first and second transistor connected in a common emitter differential pair configuration. The differential pair configuration has a pair of input terminals and a pair of output terminals. A first feedback circuit is included for providing feedback to at least one of a pair input terminals based on selected relatively slowly changing voltages between a pair of preamplifier output terminals. In this manner, the first feedback circuit minimizes differential voltages at the preamplifier output terminals. A second feedback circuit is provided for supplying feedback to at least one of the preamplifier input terminals based on relatively low frequency voltage magnitudes at one of the pair of input terminals. In this manner, a selected common mode voltage magnitude is maintained at one of the pair of input terminals.

Abstract: Rotary head recording and/or reproducing apparatus in which respective oblique tracks on a record medium are scanned, each track having an information signal area in which information data is recorded and a track following area in which a tracking control pilot signal is recorded. The track following area precedes the information signal area; and in the preferred embodiment, an additional track following area follows the information signal area. The pilot signal is recorded in only a portion of the track following area, the remainder of which has timing sync data recorded therein. In an after-recording mode the timing sync data is reproduced, detected and used as a reference to define an after-record area.

Abstract: A signal processing circuit for discriminating recording data is formed by a detector circuit for detecting zero-cross points on an equalized waveform; a PLL for generating a clock at a rate twice the baud rate of a read signal by using the zero-cross timing as an input; a divider for dividing the output of the PLL to generate two baud rate clocks having different phases from each other; and a circuit for selecting one of the two clocks using the waveform of the read signal and for connecting the selected clock to discriminator and decoder circuits. The signal processing circuit also has a table for outputting therefrom a variable branch-metric value which is adaptively controlled using the output of an A/D convertor, internal data contained in the branch-metric table, or the output of the same.

Abstract: A class IV partial response, maximum likelihood data channel for a disk drive includes an encoder connected to a data sequencer for converting user data blocks into a predetermined 8/9ths code such as a (0,4,4,) code. A precoder conveys the 8/9ths code into class IV code. An analog write driver supplies the class IV code to a data transducer head during data write-to-disk operations. A read channel connected to the head amplifies and conditions analog signals during data read operations. A quantizer produces samples of the analog signals in accordance with a quantization clock generated by a clock generator. An adaptive FIR filter means is conditions the data samples in accordance with selectable, adaptive filter coefficients. A Viterbi detector puts out the class IV code from the filtered and quantized samples. A postcoder conveys the detected class IV code into detected 8/9ths code. A decoder converts the detected 8/9ths code into user data and supplies user data to the sequencer.

Abstract: A recording apparatus of the present invention includes selective guard adding means for predicting, at the time of editing, positions of adjacency of new tracks to previously recorded tracks obtained at the time of completion of new track recording, and adds, at the time of editing, guards to locations where disturbance due to residue of erasing of the same azimuth might occur in order to remove or reduce the disturbance due to residue of erasing of the same azimuth caused at the editing point. When performing reproduction from a recording medium whereon tracks recorded by heads of at least two kinds of azimuth angles are disposed alternately and a plurality of tracks are handled as one recording unit and recorded, a reproducing apparatus of the present invention is so configured that the center of each of heads located at both ends of reproducing heads may be shifted to the inside as compared with each corresponding recording track.

Abstract: An apparatus for recording and reproducing an encoded video signal from a source encoder comprises a decoder for performing a decoding process for the encoded video signal to produce a decoded video signal, an encoder block for compressing the decoded video signal using a spatial correlation to produce an intra mode compression signal, a buffer memory for storing the intra mode compression signal, a mode controller for generating a clock pulse used to read out data in the buffer memory in accordance with a longer playing time recording and a normal playing time recording and a recording and reproducing unit for recording and reproducing the intra mode compression signal read from the buffer memory.

Abstract: A disk file subsystem is disclosed which utilizes a track address decoding circuit which converts the track address which is recorded on the magnetic media in Gray code according to a 1/6 (2,8) run-length-limited recording code to its corresponding binary track address.

Abstract: A video signal recording apparatus has a high band signal recording circuit for deeply recording onto a recording medium a high band component of a video signal separated from a composite video signal and a low band signal recording circuit for recording on a recording medium a low band component of a signal separated from the composite video signal using a much shallower recording depth.

Abstract: A head records a track (e.g. a servo track) in a memory member outside of a clean room without using reference indices. In each of a plurality of cyclical movements (e.g. revolutions), signals (e.g. servo signals) are recorded in the track in an individual number of frames. Thereafter th e distance of the unrecorded portion of the track is determined. In the next cyclical movement, the head records signals in an individual number of frames contiguous to the frames previously recorded, in a track distance dependent upon such individual number relative to the number of frames still unrecorded and upon the distance determined for the unrecorded track portion. In a last cyclical movement, the head records a single frame in a particular spatial relationship with the first and last frames. In a specific embodiment, 2.sup.N-K frames may be recorded in the K cyclical movement. Additional signals may thereafter be recorded by the head in tracks in a single cyclical movement.

Abstract: A hard disk drive (HDD) stores a plurality of parameter data for determining a filter characteristic, which is necessary for the operation of a read/write circuit, to ROM in advance. At the time of driving HDD, a host computer designates parameter data in a predetermined order, and executes a verification processing with the operation of the read/write circuit for every parameter data. The host computer determines parameter data showing a minimum read error rate as a suitable value in accordance with the result of the verification processing. A CPU of HDD stores parameter data having the suitable value determined by the host computer to a nonvolatile read/write memory. CPU sets a parameter, which corresponds to parameter data stored in the read/write memory, in the read/write circuit.

Abstract: An apparatus for recording an electric signal (A) on a magnetic record carrier (1) includes at least one pair of write heads (K.sub.1, K.sub.2) having a mechanically rigid coupling to each other and arranged on a head drum (40). The record carrier (1) is wrapped around the head drum through a wrapping angle .alpha.. The pair of heads (K.sub.1, K.sub.2) writes pairs of tracks (T.sub.1, T.sub.2 ; T.sub.3, T.sub.4 ; . . . ) on the record carrier. The apparatus further includes a signal separator (4) for dividing the electric signal into consecutive blocks, after which the signal blocks having odd sequence number (B.sub.1, B.sub.3, . . . ) are applied to a first output (5) and the signal blocks having even sequence number (B.sub.2, B.sub.4 . . . ) are applied to a second output (6). In a time-base correction circuit (7) the signal blocks (A.sub.1, A.sub.2) are time expanded or compressed. .alpha. Differs from 180.degree. .

Abstract: A magnetic tape recording apparatus having an ordinary recording mode and an editing mode in which an information signal is recorded additionally to information already stored in previously formed oblique tracks is provided in which a high degree of accuracy is assured for tracking servoing upon editing by forming on the tape a track area for tracking in an area at a predetermined position of every other one of the oblique tracks. After the recording apparatus forms a tracking area in a particular oblique track, the recording apparatus prevents its rotary head apparatus from forming another tracking area in an adjacent oblique track.

Abstract: A method of adjusting alignment of a magnetic head to be within an alignment specification in accordance with the invention includes recording on magnetic material of a test card a digital code having a greater number of bits per unit length than the set number of bits used for conventional magnetic recording of credit cards. The test card produces an electrical playback signal which varies in magnitude with head alignment at a second rate greater than a first rate produced during conventional recording. The test card is read repeatedly and alignment of the head is adjusted until a maximum electrical playback signal is produced indicating that the head is set within the alignment specification.

Abstract: The present invention includes a method, apparatus and disk format for implementation of the same to provide fault tolerant detection of ID fields for data sectors in order to eliminate errors caused by mis-alignment and mis-detection of hard sector marks. Logic is provided to initiate a time-out count at the completion of a hard sector count. The time-out count is specified to be a period of time within which a hard sector mark should be detected. If the time out count counts down and a hard sector mark is not detected, then a possible error situation arises and the fault tolerant process is initiated to compensate for the lack of detection of a hard sector mark. Thus, at the end of the time-out count, a small burst count is started.

Abstract: In a digital video tape recorder that has rotary magnetic heads for recording digital video information on a magnetic tape in the form of data blocks having a predetermined length, an ID signal is generated for each data block. The ID signal includes a number of data bits which identify the address of the data block, the information contained in the data block, and so forth. For the purpose of generating error code parity symbols, the ID signal is divided into a sequence of four-bit symbols, and at least two parity symbols are generated according to an error correction code for correcting errors in the sequence of four-bit symbols. The ID signal and parity symbols are recorded together on the magnetic tape. In this way, error correction can be performed on the ID signal during reproduction.

Abstract: A magnetic disk storage apparatus provides with a phase locked loop or a phase sync circuit including a phase comparator, a charge pump, a filter and a voltage-controlled oscillator. The phase sync circuit includes a register which is connected to an information processing system and adapted to store therein the response characteristics of the phase comparator, the charge pump, the filter and the voltage-controlled oscillator as instructed from the information processing system. In this way, in accordance with the information on the response characteristics from the information processing system, the phase sync circuit is controlled thereby to assure a stable operation even in the case of the data transfer speed varying between inner and outer track such as occurs in a magnetic disk.

Abstract: A system employing a shift register for serially delivering the bits of recreated IEC time code from a DAT recorder to a video recorder for synchronous playback of audio and video information. In order to accomplish exact synchronization despite possible variations in the frame lengths of the IEC time code recorded, the shift register is driven by a variable frequency clock. During playback the actual phase differences between the DAT frames and the IEC frames being output are detected, and deviations of these actual phase differences from desired phase differences between the DAT frames and IEC frames supplied are constantly monitored. The repetition frequency of the clock pulses applied to the shift register is increased or decreased whenever the deviation of each actual phase difference from one associated desired phase difference exceeds a predetermined limit.