Victor Company of Japan, Limited

Masami Yamazaki

Masatsugu Kitamura

Hideo Onoye

Yutaka Haramoto

Yasuhiko Fujii

Yukinobu Ishigaki

Teruo Muraoka

Isao Masuda

Isao Owaki

Susumu Saito

Kazunori Nisikawa

Kazuo Koinuma

A digital signal of data and synchronization words is distributed to a plurality of circuit paths and transformed into non-return-to-zero inverted (NRZI) signals for application to a plurality of stationary parallel magnetic heads for recording the distributed NRZI signals along first parallel tracks on a magnetic tape when driven toward one end thereof and along second parallel tracks interleaved with the first tracks when the tape is driven toward the other end thereof. Each of the transducers has a differential characteristic with which the recorded signal is detected as a ternary signal, the detected signal is converted to a binary signal to recover the original digital signal. The synchronization word is detected from the recovered digital signal to generate a timing signal indicative of the position of each binary digit of the data word with respect to the detected synchronization word. In response to the timing control signal the timing of each binary digit derived from each transducer is aligned with those derived from the other transducers and arranged into a series of successive data words for conversion to an analog signal.

Multi-track digital recording and playback system

A single multi-track head having a plurality of head gaps aligned on a center axis thereof is arranged to assume respectively first and second inclined positions with respect to a transverse axis of a magnetic recording tape. The number of the head gaps equals a half of the total number of tracks to be formed on the tape, and the head gaps are equidistantly spaced so that only odd tracks are formed to record a digital signal when the tape runs in one direction with the multi-track head in one of the first and second inclined positions. When the tape has come to the end, the tape is turned upside down to continuously record the digital signal on even tracks. Before forming the even tracks, the multi-track head is manually or automatically operated to assume the other inclined position. With this operation, the odd and even tracks have different azimuths from each other preventing cross-talk between adjacent tracks. An electrical circuit for detecting which side of the tape is at the top, and a mechanism for rotating the multi-track head either clockwise or counterclockwise may be employed for automatically placing the multi-track head in one of the first and second inclined positions.

Apparatus and method for multi-track recording of a digital signal

In order to compensate for differences in magnetic properties of recording tapes, a first and second audio test signals of different frequencies are generated by a variable frequency test signal source, recorded on a magnetic tape and reproduced to represent the magnetic properties of the tape at the different frequencies. The reproduced first test signal is stored in a microcomputer for comparison with the level of the subsequently reproduced second test signal to detect the difference therebetween for making an adjustment of the level of the second test signal in accordance with the detected difference through the use of a level adjusting device. The latter is thereafter held adjusted to the value at which the two test signals have an equal level of reproduction.

Method and system for automatically providing flat frequency response to

An automatic attenuation circuit comprises a variable loss attenuation circuit that drives circuitry for detecting the level of the output signal of the variable loss attenuation circuit. The level detector drives a periodically reset integrator, which in turn feeds a signal to a comparator, also responsive to a reference. A control circuit responsive to the output signal of the comparator controls the attenuation factor of the variable loss attenuation circuit. The control circuit, which may be a microcomputer, is so programmed that the attenuation factor of the variable loss attenuation circuit is stepwisely increased until the level of the output signal of the variable loss attenuation circuit becomes equal to or below a predetermined level.

Automatic attenuation circuit

An automatic recording level controlling circuit comprises an audio test signal oscillator, a variable loss attenuation circuit, level detecting circuitry and a control circuit for controlling the attenuation factor of the variable loss attenuation circuit in accordance with the output of the level detecting circuitry. The level of a reproduced signal corresponding to the test signal is detected to see the deviation from a reference level so that the attenuation factor of the variable loss attenuation circuit is controlled in such a manner that the level of the reproduced signal is as close to the reference level as possible.

Automatic recording level controlling circuit

An automatic bias level setting circuit for tape recorders includes a variable loss attenuator for stepwisely increasing the level of a high frequency bias signal which is superposed on a constant amplitude audio test signal. The recorded signal is detected by means of an envelope detector coupled to the playback head and fed into a resettable integrator for integrating the input signal in response to each stepwise variation of the signal to generate a series of sawtooth waves. The output of the integrator is coupled to a maximum peak detector to detect the maximum peak point of the recorded test signal to determine an optimum bias level in relation to the detected peak point.

Bias level setting circuit for tape recorders with staircase high

An FM wave received by an antenna is fed via an AGC circuit to a first FM demodulator and to a compensation signal generator which includes an envelope signal generator, a capacitor, a function generator, an analog multiplier, an SSB modulator, and a second FM demodulator so that the output signal of the compensation signal generator is added to the output signal obtained by the first FM demodulator to offset the multipath distortion contained in the received FM wave.

Circuit arrangement for eliminating waveform distortion of an

A signal processing circuit has a circuit organization having a pair of crosstalk circuits respectively including at least delay circuits each of a delay time .tau. and adapted to add or cancel crosstalk components to or in input signals in correspondence with the transfer characteristics between sound sources and the two ears of a listener. Each crosstalk circuit has means for attenuating components of frequencies represented by (2n-1/2.tau.) (where n is a positive integer).

Signal processing circuit

A phase-shifting circuit comprises a first transistor circuit having a base to which an input signal is applied, first and second resistors of equal resistance values connected mutually in series and between an emitter of the first transistor circuit and ground, a third resistor connected at one terminal thereof to the emitter of the first transistor circuit, a capacitor connected between the other terminal of the third resistor and ground, and a second transistor circuit having a base connected to said other terminal of the third resistor and an emitter connected to the junction between the first and second resistors, an output signal being led out from a collector of the second transistor circuit.

Phase-shifting circuit

A compression and expansion system comprises a control circuit including a variable impedance element, whose impedance is varied in accordance with a control signal applied thereto. The system has a frequency-response characteristic which varies in accordance with variation of the impedance of the variable impedance element. A control signal is formed in accordance with the level of an input signal and is applied to the variable impedance element of the control circuit thereby to vary the impedance thereof. A switching means forms passing paths in a manner such that, at the time of compressing, the input signal is supplied by way of the control circuit to a negative feedback amplifier. At the time of expanding, the input signal is supplied to the negative feedback amplifier, and, at the same time, the output of the negative feedback amplifier is fed back by way of the control circuit to the input of said negative feedback amplifier. The control circuit comprises a variable high-frequency range increasing circuit which operates when the input signal level is relatively low. The control circuit increases the high-frequency component in accordance with the variation of the impedance of the variable impedance element. A variable high-frequency range decreasing circuit operates, when the input signal level is relatively high, to decrease the high-frequency component in accordance with the variation of the impedance of the variable impedance element.

Compression and expansion system with enlarged dynamic range

In a record disc reproducing apparatus, an abnormal sound eliminating system comprises a variable filter in the transmission system for a signal reproduced from a record disc. The filter does not pass the signal band, which is variable. A control signal generator produces a control signal in accordance with the frequency of a carrier wave reproduced from a multichannel record disc. The non-passed signal band of the variable filter is variably controlled by the control signal from the control signal generator, to eliminate a carrier wave reproduced with a frequency lower than a specific frequency. This low frequency wave appears when the multichannel record disc rotates at a low speed, less than a specific normal rotational speed. This limitation prevents the generation of abnormal sound due to the reproduced carrier wave of low frequency.

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Yokohama, Japan

Masami Yamazaki