Abstract: A data object has a lock and a condition indicator associated with it. Based at least partly on detecting a first setting of the condition indicator, a reader stores an indication that the reader has obtained read access to the data object in an element of a readers structure and reads the data object without acquiring the lock. A writer detects the first setting and replaces it with a second setting, indicating that the lock is to be acquired by readers before reading the data object. Prior to performing a write on the data object, the writer verifies that one or more elements of the readers structure have been cleared.

Abstract: A data object has a lock and a condition indicator associated with it. Based at least partly on detecting a first setting of the condition indicator, a reader stores an indication that the reader has obtained read access to the data object in an element of a readers structure and reads the data object without acquiring the lock. A writer detects the first setting and replaces it with a second setting, indicating that the lock is to be acquired by readers before reading the data object. Prior to performing a write on the data object, the writer verifies that one or more elements of the readers structure have been cleared.

Abstract: A data object has a lock and a condition indicator associated with it. Based at least partly on detecting a first setting of the condition indicator, a reader stores an indication that the reader has obtained read access to the data object in an element of a readers structure and reads the data object without acquiring the lock. A writer detects the first setting and replaces it with a second setting, indicating that the lock is to be acquired by readers before reading the data object. Prior to performing a write on the data object, the writer verifies that one or more elements of the readers structure have been cleared.

Abstract: A computer-implemented method according to one embodiment includes performing anti-aliasing filtering on each of a plurality of signals, each signal having a frequency that is a different fraction of a frequency of a data read clock. An amplitude of each of the signals is measured after the anti-aliasing filtering. In response to the amplitudes of the signals being within a predefined range, anti-aliasing settings used during the anti-aliasing filtering are stored. In response to the amplitudes of the signals being outside the predefined range, the anti-aliasing settings are changed. A computer program product according to another embodiment includes a computer readable storage medium having program instructions embodied therewith. The computer readable storage medium is not a transitory signal per se. The program instructions are executable by a processing circuit to cause the processing circuit to perform the foregoing method.

Abstract: Receiving an indication of a frequency ratio of first and second clocks; generating an indication of a number of clock pulses of the second clock occurring between first and second clock pulses of the first clock; and generating an indication of a time offset between (1) a clock pulse of the second clock occurring between the second clock pulse and a third clock pulse of the first clock, and (2) the second clock pulse of the first clock. Also, receiving an input data word representing a fractional number, a first part of the input data word comprising an integer portion of the fractional number and a second part comprising a decimal portion of the fractional number; providing a first output data word that is either the first part of the input data word or an increment by one of the first part; and providing a second output data word that is an integer multiple of the second part.

Abstract: A data storage device is disclosed comprising a head actuated over a disk, and a two-dimensional (2D) equalizer comprising a plurality of coefficients. A plurality of stored coefficients are accessed based on a first off-track offset of the head in order to first initialize the coefficients of the 2D equalizer, and then the coefficients of the 2D equalizer are first adapted based at least on a first read signal to generate first adapted coefficients. The plurality of stored coefficients are accessed based on a second off-track offset of the head in order to second initialize the coefficients of the 2D equalizer, and then the coefficients of the 2D equalizer are second adapted based at least on the first read signal to generate second adapted coefficients.

Abstract: A Data Storage Device (DSD) includes at least one disk surface for storing data and a memory for storing a bitmap buffer. A segment of a disk surface is identified that includes at least one defect region, and a segment bitmap is generated for the segment indicating the at least one defect region within the segment. The segment bitmap is stored in the bitmap buffer.

Abstract: Preamble fields are written on a storage disk in a hard disk drive in a way that reduces track squeeze. Preamble fields for a particular data storage track on the storage disk are written over multiple revolutions of the storage disk to eliminate low-frequency variations of the preamble stitch line from an ideal position of the preamble stitch line. By writing the preamble fields for one data storage track over multiple revolutions, and by writing the preamble fields in each revolution to non-consecutive servo wedges, low-frequency variations of the preamble stitch line from its ideal position can be converted to high-frequency variations of the preamble stitch line that do not produce low-frequency track squeeze.

Abstract: Methods and apparatus describe processing of data for recording to a storage device. An apparatus includes, in at least one aspect, a plurality of buffers and circuitry configured to encode data stored in one buffer of the plurality of buffers concurrently with storing data in another buffer of the plurality of buffers and to write the encoded data from the one buffer to a storage device concurrently with encoding the stored data in the other buffer.

Abstract: A method for randomizing data to mitigate false VFO detection is described. In one embodiment, such a method includes simultaneously receiving multiple input data streams. Each input data stream is associated with a different track on a magnetic tape medium. The input data streams are simultaneously scrambled to produce multiple randomized data streams. The input data streams are scrambled such that different bit patterns are produced in the randomized data streams even where corresponding bit patterns in the input data streams are identical. The randomized data streams are simultaneously written to their associated data tracks on the magnetic tape medium.

Abstract: Systems, methods and computer program products for writing and reading a plurality of data sets and error codes are described. In some implementations, a magnetic disk controller can be provided that includes an error code unit configured to generate one or more error codes for each of a plurality of data sets to be written onto corresponding sectors of a medium. The magnetic disk controller can also include a buffer unit configured to store each data set and an error code in an associated buffer, and an encoding unit configured to encode the plurality of data sets. In some implementations, at least one data set is encoded concurrently with the buffer unit storing another different data set in the associated buffer. The magnetic disk controller can also include a control unit configured to write each encoded data set and a corresponding error code onto a corresponding sector.

Abstract: A method and system for disk I/O (input output) command splitting in a computer system. The method includes tracking a head position of a disk drive. Upon receiving a request for data from the disk drive, a first split access is executed to read a first portion of the data and a second split access is executed to read a second portion of the data. The second split access is executed after a rotation of the disk drive. The first split access and the second split access are used to fulfill the request for data.

Abstract: There is provided an information reproduction apparatus that can suppress degradations in the qualities of reproduced data and timing from due to interpolation errors when performing interpolation timing recovery, and that can avoid degradation in the stability of the system due to an increase in the timing recovery loop delay. An information reproduction apparatus (100) for reproducing data and timing from an analog signal including data information and timing information is provided with an expected value generator (106) for outputting plural expected values, and a maximum likelihood detector (107) for outputting data that corresponds to a sequence of the highest likelihood with an output sequence of an A/D converter among the plural expected value sequences, at the timing of a second clock.

Abstract: Aspects of the invention may provide a method and system for adjusting a gain and/or a frequency response of an input signal for a multimode PHY device. A signal divider may apportion the input signal into a gain adjustment signal and/or an equalization adjustment signal upon receipt of the input signal. A signal adjuster coupled to the signal divider may adjust a gain of the apportioned gain adjustment signal within the multimode PHY device. An equalizer coupled to the signal divider may be configured to equalize the equalization adjustment signal within the multimode PHY device. A summer coupled to the equalizer and signal adjuster may be adapted to sum the adjusted adjustment signal and the equalized equalization adjustment signal within the multimode PHY device to create an output equalized signal having a desired gain and/or frequency response.

Abstract: A method of splitting a signal (10) into two parts (10?, 10?) is disclosed together with signal processing circuitry (22) for the same. The method comprises the steps of derotating the signal (10) whereby the frequency band of the derotated signal overlaps zero frequency; and splitting the derotated signal into two parts, a first signal part (10?) consisting substantially of positive frequency signal components and a second signal part (10?) consisting substantially of negative frequency signal components. Also disclosed is methods, incorporating such a method of splitting a signal, for identifying the presence of in-band interference (11) in a signal and for despreading a spread spectrum signal.

Abstract: A transmitter is disclosed for transmitting a first and second digital information signal. Said first digital information signal comprises first frames having at least a first synchronization signal and a data portion stored in them. The transmitter processes the second digital information signal into subsequent second frames comprising blocks of information of the second digital information signal. Composite frames have been obtained by inserting a second synchronization signal and at least the data portion of the first frames into the second frames by using buried data techniques. Prior to inserting at least the data portion of the first frame into a second frame the first synchronization signal is stripped from the first frame. The sequence of composite frames is transmitted via the transmission medium.

Abstract: To provide an integrated information processing unit that is capable of producing images and sounds of high quality. It includes a control unit, information processing units, and a merge unit. Each of the information processing units includes a counter for synchronization purpose. The information processing units performs a predetermined processing based on the measured value obtained by the counter for synchronization purpose. The control unit simultaneously provides a trigger of measurement of synchronization clocks to all counters for synchronization purpose and individually provides a reset signal to the counters for synchronization purpose which the reset signal is for initializing the measured value obtained by the counters for synchronization purpose. The merge unit merges information processed by the information processing units according to the unit of output (in frame) of, for example, a display device.

Abstract: An optical servo writer system including a laser subsystem to generate a multiplicity of light beams, a lens positioned to receive and focus the light beams and a spatial filter positioned in the system so as to allow a subset of the light beams to pass through the filter. The multiplicity of light beams includes the subset that contains the desired beams, or the servo beams, and also the undesired beams, called the ghost beams. The system further includes a digital linear tape positioned adjacent the spatial filter with the spatial filter allowing the subset of light beams to hit the digital linear tape and produce servo marks. The spatial filter includes openings positioned to allow the subset of light beams to pass through the filter. The openings may be staggered relative to the digital linear tape to prevent debris generated by the marking process from clogging the openings.

Abstract: A recording device for recording film information concerning photography made to each of a plurality of exposure areas on respective recordable areas corresponding to the plurality of exposure areas, includes: a film feeder which feeds the film; a recording head which records a film information signal on a corresponding recordable area, the signal having a specified frequency; and a frequency controller which changes the signal frequency during the time when the film information is being recorded on the recordable area. The recording device makes it possible to simplify the construction of a camera, and to record film information with high density and stability.

Abstract: During shuttle mode operation in a system for the reproduction and storage of frequency separated video signals, the read head intersects a plurality of tracks corresponding to different fields of the image rather than following complete tracks. Accordingly, the full information for any one field is not recovered. To provide an image during shuttle mode, the system reads the dc luminance information of the tracks it intersects at the part where this information is stored. As the information content of the dc luminance information is relatively high, a recognisable image can be formed from this information alone. The dc luminance information is stored in the centre of the tracks with the other components arranged in order of increasing frequency towards the edge of the tape. The data which is most important to generation of a high quality image is stored in a place where it is less likely to be degraded.

Abstract: A signal processing system for a high resolution digital video tape recorder (VTR) includes circuitry which processes the high resolution video signal to produce a relatively low resolution video signal which may be recorded on the tape with the high resolution video signal. The low resolution video signal is encoded using intra-frame techniques and recorded in fixed-length segments which appear at predetermined locations in the tape tracks. Low resolution segments representing images in different frames may be recovered and combined to produce an image which is suitable for display in trick-play modes. During normal play modes, the data stream representing the high resolution image is recovered in sequence. Accordingly, this high resolution image may be encoded using predictive coding techniques as well as intra-frame techniques.

Abstract: Apparatus is described for multiplexing data recorded in a spatially and temporally demultiplexed manner on tape 12 and replayed by a plurality of replay heads A, B, C, D organized in groups, where each group includes a plurality of replay heads A/C, B/C, connected in common to a head channel 42, 44. First multiplexers 84, 92 multiplex the data in respective head channel, the output of the first multiplexers being stored in respective video buffers 86, 94. A second multiplexer 88 then selectively addresses the video buffers in response control signals to produce a multiplexed output which can reliably be reproduced even under extreme error conditions and in all playback modes.

Abstract: An image signal recording and reproducing apparatus comprises a head array having a plurality of head gaps for recording and reproducing the image; a piezoelectric actuator having a polarization direction and for moving the head array downwards and upwards in a width direction of a track in accordance with input of a driving voltage; a phase comparator for generating a phase control signal in accordance with a phase difference between the head array and the track; a unit for outputting the driving voltage to the actuator in accordance with the phase control signal; and a signal processing unit for recording and reproducing the image signal on and from the track by the head array.

Abstract: A high-definition television receiver includes circuitry to decode a received high-definition television signal to produce a digital data stream representing the corresponding high-definition television image. In addition, the receiver includes circuitry which generates a signal representing a reduced resolution image from the decoded data stream. The receiver provides both the high-definition television signal and the reduced resolution signal at an output port. A video tape recorder (VTR) receives the two signals, segments them and formats them onto the tape in a manner which allows a majority of the reduced resolution segments to be recovered and displayed in at least one of the VTR's trick-play modes. The reduced resolution image may be from the same channel or from a different channel and may also be displayed as an inset picture (PIX-IN-PIX) in the main high-definition image.

Abstract: An 8-mm video tape recorder receives a main audio signal which is transmitted as a monaural or stereophonic audio signal, and an auxiliary audio signal (SAP) which is selectively transmitted with the main audio signal, and records the main audio signal as first and second audio signals. A SAP demodulator determines whether the auxiliary audio signal is transmitted or not. When the auxiliary audio signal is transmitted as determined by the SAP demodulator and recording of the auxiliary audio signal is indicated through a terminal by the user, selector switches are shifted to supply the auxiliary audio signal to a frequency demodulator which records the auxiliary audio signal as the first audio signal on an 8-mm magnetic video tape. The 8-mm video tape recorder can record video signals accompanied by audio signals at all times.

Abstract: A digital signal magnetic recording/reproducing apparatus subjects a digital signal to a digital amplitude phase shift keying and records and reproduces the modulated signal thus obtained on a magnetic recording medium. Use of the digital amplitude phase shift keying technique makes it possible to remove the direct-current component in the recording signals, and to improve the utilization efficiency of the recording frequency band, thus making high density recording possible. In addition, since a plurality of modulated signals are frequency-multiplexed and recorded, almost the entire frequency band recordable on a magnetic recording medium can be utilized, resulting in an increase in recording density. Further in addition, a pilot signal produced by frequency-converting a carrier is frequency-multiplexed with a modulated signal and recorded and reproduced and the carrier is reproduced from the reproduced pilot signal, so that a redundant part for reproducing the carrier is not necessary.

Abstract: During shuttle mode operation in a system for the reproduction and storage of frequency separated video signals, the read head intersects a plurality of tracks corresponding to different fields of the image rather than following complete tracks. Accordingly, the full information for any one field is not recovered. To provide an image during shuttle mode, the system reads the dc luminance information of the tracks it intersects at the part where this information is stored. As the information content of the dc luminance information is relatively high, a recognisable image can be formed from this information alone. The dc luminance information is stored in the center of the tracks with the other components arranged in order of increasing frequency towards the edge of the tape. The data which is most important to generation of a high quality image is stored in a place where it is less likely to be degraded.

Abstract: An information signal recording and reproducing system for recording and reproducing an information signal on and from a recording medium comprises a modulation circuit for modulating the information signal to form a modulated signal involving a number of pulses, a first frequency divider triggered responsive to a leading edge of the pulses in the modulated signal to produce a first frequency-divided signal having a frequency substantially lower than that of the modulated signal, a second frequency divider triggered responsive to a trailing edge of the pulses in the modulated signal to produce a second frequency-divided signal having a frequency substantially lower than that of the modulated signal, a recording device for recording the first and second frequency-divided signals on the recording medium, a reproducing device for detecting the first and second frequency-divided signals recorded on the recording medium to produce a first reproduced frequency-divided signal and a second reproduced frequency-divide

Abstract: In a RAID level 5 disk drive subsystem, one or more additional disk drives, called "reserve" disks are intercoupled to the array of disk drives and a control system is included for storing recovered digital data on the additional disk drive if a sector on one of the disk drives becomes defective. The system reduces the number of disk accesses required to obtain the information stored on the defective sector. Once the information has been recovered, it is then stored on the "reserve" disk. Thereafter, whenever this information is required, the system reads the required information from the "reserve" disk, instead of going through an entire recovery process for the defective sector. Since the recovery process can take a time that is greater than several disk access times, the present invention improves the speed and the availability of data.

Abstract: In an audio and video recording apparatus, a video signal is separated into a luminance signal and a chrominance signal. The luminance signal is separated into low frequency and high frequency components. The high frequency component signal is subjected to balanced modulation to be thereafter band-compressed by interleaving the lower side band thereof to the low frequency component. The chrominance signal is processed to be a line sequential color difference signal. An audio signal is sampled and encoded. The luminance signal, the color difference signal and the audio signal are subjected to time-axis compression multiplexing in one frame with a synchronizing signal, address signals and control signals. The multiplex signal is recorded on a recording medium.

Abstract: Run length limited codes, such as (1,7) codes are recovered with a dual channel recovery system in which the high resolution channel normally supplies the output (recovered) signal. The low resolution channel includes a detector, such as a delay device and gate, to detect a predetermined absence of transitions in the low resolution signal (which is indicative of long strings of successive zeros) to inhibit the high resolution channel from supplying the output. The result is to effectively block the high resolution channel from providing a false output.

Abstract: A digital recording and reproducing system wherein luminance signals digitized and converted into the low speed signals and chrominance signals digitized at the time of recording are distributed among a plural number of channels and the signals of the plural number of channels are recorded respectively on a recording medium. At the time of the reproduction, the signals of the plural number of the channels are reproduced respectively from the recording medium and combined to form the luminance signals and the chrominance signals respectively. The luminance signals in the combined signal are converted into a high speed signal and output terminals for outputting dubbing signals from the system for dubbing the signals are led. The output side of a low speed-to-high speed converter and a channel combination circuit.

Abstract: A signal processing circuit for a video recording and reproducing apparatus comprises a ramp inserting circuit for inserting a ramp waveform at periodic intervals into a video signal during recording. The ramp waveform varies linearly as a function of time from the minimum to the maximum level of the video signal. On playback, the inserted ramp is periodically detected from a reproduced video signal by a ramp detector. The waveform of the detected ramp is corrected to improve its signal-to-noise ratio by an averaging circuit and applied to a transfer circuit having a transfer function describing the relationship between the original ramp waveform and the corrected ramp waveform. The waveform of the reproduced video signal is transformed according to the transfer function.

Abstract: A multitrack magnetic recording and reproducing device of the type, which converts analog signals into digital signals and records and reproduces such converted data by splitting onto a plurality of tracks, comprises heads for both high and low recording densities such that track pitches corresponding to them are at an integral ratio. It includes a reproducing circuit having detecting-decision making means such as multiplexers which, when information recorded by a head for lower recording density is reproduced by corresponding heads for higher recording density, is adapted to determine whether any of the outputs from these heads is incorrect.

Abstract: A method for superimposed recording of a first signal and a second signal with frequency which is less than the frequency for the first signal, in a perpendicular magnetic recording medium by means of a ring-shaped magnetic head. The mutually superimposed first and second signals are supplied to the magnetic head. The value of the first signal current to be supplied to the magnetic head is set at a value which is greater than the current value for which the reproduced output level of the first signal that was recorded on the magnetic recording medium attains a maximum, and a satisfactory superimposed recording characteristic can be obtained by such an arrangement.

Abstract: A video signal recording and reproducing apparatus comprises a circuit for recording an FM recording video signal onto a recording medium, a demodulator for reproducing and demodulating the recorded signal from the recording medium back into the original video signal, a noise reduction circuit for reducing a noise component in the reproduced video signal. The noise reduction circuit has a first delay circuit for delaying the reproduced video signal by one horizontal scanning period (1H), a first differential amplifier supplied with the reproduced video signal and with a 1H delayed reproduced video signal, a first limiter for amplitude-limiting an output of the first differential amplifier, and a subtracting circuit for performing a subtraction between the reproduced video signal and an output of the first limiter.

Abstract: In recording an analog signal using two recording heads equally-spaced on a rotating drum, a magnetic tape is wrapped about a guide drum over an angular extent of 90.degree., so that there are recording periods when a head is tracing the tape and periods when no head is tracing the tape. The analog signal to be recorded is converted to a pulse-code-modulated (PCM) digital signal in real-time periods which are longer than the recording periods during which a head traces the tape. The PCM signals are time-base compressed to be slightly less than the rotary head contact interval and additional data such as parity data and cyclic redundancy check codes are added to the PCM signals to form a composite signal, which is written back into a memory system.

Abstract: A dual channel read recovery system having a high resolution channel and a low resolution channel and logic for recovering digital information from the high and low resolution signals from the channels, is improved by the inclusion of a variable delay in the low resolution channel. The variable delay is responsive to the high and low resolution signals to more closely match the delays in both channels.

Abstract: A video signal recording apparatus comprises a guiding mechanism for guiding a magnetic tape, and a main head and a sub-head for scanning and recording a composite video signal throughout a predetermined range of the magnetic tape. The main head and the sub-head is separated by a predetermined angle and mounted on a rotary body with a difference in their height positions. The main head scans over the magnetic tape to record a signal by forming a first track part comprising a plurality of tracks formed obliquely with respect to the longitudinal direction of the magnetic tape, in a first region along the width direction of the magnetic tape, while the sub-head scans over the magnetic tape to record a signal by forming a second track part comprising a plurality of tracks formed obliquely with respect to the longitudinal direction of the magnetic tape, in a second region different from the first region along the width direction of the magnetic tape.

Abstract: A gain control circuit for an audio signal recorder includes a first transmission path having a variable gain amplifier for compressing an audio signal with a first gain characteristic in response to a first control voltage supplied thereto, a second transmission path having a variable gain amplifier for compressing the audio signal with a second gain characteristic different from the first gain characteristic in response to a second control voltage supplied thereto, a control circuit responsive to at least one of the compressed audio signals from the variable gain amplifiers for producing the control signals, and an adding amplifier for adding the compressed audio signals from the first and second transmission paths whereby the compressed audio signal from the first transmission path is effectively transmitted for recording when the level of the audio signal is below a predetermined value and the compressed audio signal from the second transmission path is effectively transmitted for recording when the level

Abstract: A method of changing video recordings with or without audio information on a single video recording/playback unit, comprising reading the originally recorded signals of a first of several tracks on a recording medium and re-recording said signals on the same first track or on a second track, as well as erasing the originally recorded signals, in order to vacate tracks for further new recordings, and devices for carrying out said method. The devices include recording/playback and erase head combinations, and a circuit for separating, changing and re-recording the video and/or audio signals.

Abstract: A PCM recording apparatus is disclosed in which digitized left and right channel sample signals each having error detecting bits and a signal indicative of a correlation such as sum or difference of the two samples are recorded on a record medium in a predetermined arrangement, and an error in coding is detected from the correlation signal.

Abstract: In a video disk system a mark along a record data track is modulated in length to represent multi-bit binary code blocks of a first length (such as three or fout bits) and the player system associated with the disk operates in multi-bit code blocks that are generally longer (for example eight bits) so that two marks on the disk may represent a single code block in the associated system. The bits of the code block in the associated system are assigned to bit positions of the appropriate number of marks on the disk in a way that minimizes the effect of errors in the operation of initially writing or subsequently reading a mark. The increments of mark length are also made non-linear to further minimize the effect in the associated system of errors in mark length.

Abstract: A head wheel is rotated at a predetermined, essentially constant speed within a tape cylinder over which a tape is guided in a spiral path, on which video signal tracks are recorded in inclined track portions. The instantaneous position of the head wheel is determined, for example by a tacho generator applying signals to a counter, phase-synchronized by the outputs from the head wheel tacho generator.

Abstract: Apparatus for directly recording television signals on a magnetic medium strips out sync and blanking information. Low frequency components of the television signals are time compressed, i.e. frequency shifted, and recorded as a substitute for the stripped-out sync and blanking information. Thus, high frequency components of each video line are recorded, followed by that line's low frequency components, thereby facilitating the playback of low frequency information. In time compressing the low frequency information, the video signal content of a line is sampled at a predetermined rate. Each sample is then quantized for purposes of improving the playback signal-to-noise ratio, i.e. the effect of tape modulation, and other, noise is nullified by sample quantization. And, to cut the bit rate resulting from sample quantization, a preferred form of the invention groups the quantized bits and records analog representations of the bit groups.

Abstract: Method of recording and reproduction of wide frequency band video signals onto or from a magnetizable recording carrier, carried out by the following means: means for separating of the video frequency signals into first and second signals of lower and upper frequency range respectively, for converting said second signal into a third signal the frequency range of which equaling that of said first signal, for frequency modulating a carrier wave frequency by said first and third signals and for recording the frequency modulated signals by means of a twin head, for reproducing the recorded signals by means of a twin head and for amplifying, limiting and demodulating the recorded signals and reconverting the third signal into its original frequency range and combining the so reconverted third signal and said first signal.

Abstract: In order to provide fast- and slow-motion reproduction of video signals a tape is played back at a different velocity, at which the scan traces provide acceptable signals for only a portion of each track at a time, the acceptably picked-up picture lines of these track portions are temporarily stored (others being excluded) and then played back under conditions satisfying television reception standards, in an order determined by an address made up of the line number and a track and field identification provided in response to track and field beginning pulses recorded on the tape. The address can be recorded together with the video signals or can be generated by counting means during the reproduction of the video signals. The tape transport speed is automatically adjusted slightly, if necessary, with respect to the speed setting, to avoid duplicate storage of corresponding lines in successive fields at the expense of omission of other lines.

Abstract: Apparatus for directly recording television signals on a magnetic medium strips out sync and blanking information. Low frequency components of the television signals are time-compressed, i.e., frequency shifted, and recorded as a substitute for the stripped-out sync and blanking information. Thus, high frequency components of each video line are recorded, followed by that line's low frequency components, thereby facilitating the playback of low frequency information. In a preferred form, the low frequency video information is time-compressed sufficiently to provide time, during the time slot which corresponds to sync and blanking information, for the recording of reference signal information. During playback, the reference signal information is employed to set the gain of the playback circuit.

Abstract: For sensing the peaks of an electric signal reconverted by a magnetic head from a digital signal stored on a magnetic tape or other recording media, a half-wave rectifying diode is connected to the magnetic head via an amplifier. The output of the half-wave rectifying diode is connected directly to a resistance-capacitance differentiating circuit, without interposition of a slicer therebetween. An output from the differentiating circuit is compared with a variable level-setting reference voltage in a substantially connected comparator circuit, and the latter produces output pulses the trailing edges of which substantially correspond in time to the peaks of the output from the magnetic head. A pulse trailing edge sensing circuit connected next to the comparator circuit produces output pulses of comparatively short durations corresponding to the trailing edges of the comparator output pulses.

Abstract: The invention concerns a dynamic range compressor type encoder or expander type decoder, in which a main signal component in a main path is boosted or bucked by a further signal component derived from a point in the main path by a further path having the characteristics of so restricting the further signal component that the boosting or bucking action is only appreciable below a low level threshold. In the present invention the further signal component is a difference signal formed between a direct signal derived from a point in the main path and a delayed version of either the same signal or of another signal derived from another point in the main path. At the frequency equal to the reciprocal of the delay, and at harmonics of this frequency, the direct and delayed signals cancel. The compressor or expander action, and hence noise reduction action, takes place only at intervening frequencies.