Abstract: A magnetic recording and reproducing apparatus wherein synchronizing separation of a reproduction video signal can be performed accurately and a stabilized reproduction video signal can be obtained. The magnetic recording and reproducing apparatus includes a switch device for selectively inserting, upon recording, a PCM modulated audio signal into a blanking period of an FM modulated video signal, a PCM region signal generator for identifying a region of a PCM modulated audio signal in a reproduction signal reproduced by a rotary head and generating a control signal representative of a PCM audio signal region, an FM demodulator for FM demodulating a reproduction signal from the rotary head into a reproduction FM demodulation signal, and a clip circuit for clipping a lower end portion of a PCM audio signal region of a reproduction FM demodulation signal from the FM demodulator in accordance with a control signal generated from the PCM region signal generator.

Abstract: The video signal reproduction apparatus having two kinds of equalizing circuits to correct the level of a frequency-modulated luminance signal, that is, a first equalizing circuit which raises the level of the upper sideband range of the frequency-modulated luminance signal and a second equalizing circuit which raises the level of the lower sideband range of the frequency-modulated luminance signal, so that the part of the frequency-modulated luminance signal where a horizontal synchronizing signal is not modulated is processed by the first equalizing circuit, while the part of the frequency-modulated luminance signal where a horizontal synchronizing signal is modulated is processed by the second equalizing circuit.

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: An apparatus for reproducing from a recording medium a frequency-modulated audio signal which has its carrier level in a specific period determined according to the kind of information and for producing the audio signal after processing the reproduced audio signal is arranged to control the signal processing action according to the output of a detecting circuit which detects the level of a difference between the carrier level of the frequency-modulated audio signal obtained in the specific period and the carrier level obtained in a period other than the specific period or detects changes taking place in the carrier level. This arrangement enables the apparatus to process the audio signal appositely to the kind of the frequency-modulated signal thereof without recourse to any additional reproducing circuit solely for this purpose. Further, the apparatus is arranged to prevent any faulty signal processing action by nullifying as necessary the output of the detecting circuit.

Abstract: A magnetic recording/reproducing apparatus, which includes: a reproduced level detector for detecting the level of a reproduced signal and a memory for storing the reproduced level detected by the detector; and when recording a video signal, the signal is recorded and reproduced in advance, and this reproduced level is stored in the memory, so that an amount of emphasis of a detail emphasis circuit in a reproducing system and an amount of equalization of an FM equalizer in the recording system can be controlled in accordance with the stored reproduced level; while when reproducing the video signal, the level of a reproduced FM luminance signal is detected by the reproduced level detector, so that an amount of equalization of an FM equalizer, an amount of cancellation of a line noise canceler, and an amount of cancellation of a noise canceler in a reproducing system can respectively be controlled in accordance with the detected reproduced level; whereby the characteristic of a video tape can be controlled in a

Abstract: There is provided an audio signal magnetic recording and reproducing apparatus in which a frequency modulated luminance signal and a frequency modulated audio signal are sequentially recorded and reproduced onto/from the same magnetic tape as recording loci each having predetermined angle of inclination for the tape running direction by a plurality of rotary heads having different azimuth angles, wherein the apparatus increases a recording level of the frequency modulated audio signal for the vertical sync signal period of the luminance signal.

Abstract: A still video device in which identical image signals for one still image are recorded in two tracks of a recording medium, and the image signals recorded in the tracks are reproduced. The still video device has two magnetic heads for recording and reproducing the image signals. The image signals reproduced by the two magnetic heads are added together. An envelop-detected signal of the added-together image signals is obtained, and a phase of the reproduced signal is controlled in such a manner that the envelop-detected signal reaches a maximum value, whereby a C/N ratio of the reproduced signal is improved. Further, the recording mode of the image signals are determined based on the added-together image signals.

Abstract: A control signal reproducing circuit which, during a VISS operation, clips a reproduced residual signal at a certain level or, controls a feedback amount of a control pulse by varying a pole value in order to reduce the cut-off frequency and (suppress high band components, thereby reducing the reproduced gain of the residual signal and preventing faulty VISS operation due to the residual signal.

Abstract: An apparatus for recording an information signal on a disk by a laser beam is comprises of a rotating device for driving the disk with a constant angular velocity, a modulator for frequency-modulating the information signal in a predetermined manner, a control circuit for controlling the laser beam by the frequency-modulated information signal, and a record circuit for changing the characteristics of the information signal in accordance with the position of the laser beam on the disk.

Abstract: A magnetic reproduction apparatus which uses a magnetic recording medium on which frequency-modulated signals produced by frequency-modulating a carrier with video signals are recorded, and demodulates reproduced signals from the magnetic recording medium into the video signals. The apparatus includes a frequency convertor for causing the reproduced signals to shift to a higher frequency region and a pulse-count-type FM demodulator for demodulating the reproduced signals which have shifted to the higher frequency region into the video signals. This arrangement restrains the mixing of the reproduced signals in the video signals. Therefore the video signals are reproduced with lessened waveform distortion, achieving a high-quality image.

Abstract: A video tape recorder for recording and/or reproducing a stereo frequency-modulated audio signal by a pair of carrier signals of an indispensable first carrier signal and an additional second carrier signal is comprised of a circuit for demodulating the second carrier signal to provide a demodulated output, and a comparator for comparing an amplitude of the demodulated output with a predetermined value. When the amplitude of the demodulated output is below the predetermined value, it is determined that the second carrier signal exists.

Abstract: Apparatus is provided for recording and reproducing video and audio signals on a record medium, wherein the audio signal may be of at least two different types subjected to respectively different types of audio processing. A recording section produces frequency modulated audio signal components and selectively adjusts the level of at least one FM audio signal component during the video blanking intervals as a function of the type of audio signal being modulated. Then, the FM audio signal components and the video signal are combined and recorded. A reproducing section separates the reproduced FM audio signal components from the reproduced video signal and detects the level of at least one separated FM audio signal component during blanking intervals. The FM audio signal components are demodulated and processed pursuant to a selected type of audio processing dependent upon the detected level of the FM audio signal component.

Abstract: A magnetic recording correction circuit for a video tape recorder comprises a first multiplier supplied with a first signal to output a signal having a frequency which is twice as high as that of the first signal; a second multiplier supplied with a second signal and a first multiplier output signal outputted from the first multiplier to output a correction signal having a component of a sum frequency of the second signal and the first multiplier output signal and a component of a difference frequency therebetween; an adding circuit for adding the first and second signals and the correction signal; and a phase shifter provided on the output side of the second multiplier to exert a phase characteristic on the correction signal with respect to the first and second signals.

Abstract: A circuit for automatically controlling a carrier frequency of a video tape recorder includes a voltage controlled oscillator, a phase detector for generating an error signal representing a phase difference between an output signal of the voltage controlled oscillator and a reference signal, an integrating circuit for converting the error signal into an error voltage, and a frequency modulator with the same structure and characteristics as the voltage controlled oscillator for generating a carrier signal having a carrier frequency equal to a frequency of the reference signal in response to both the error voltage and a voltage level of a luminance component of a video signal voltage controlled oscillator changes the oscillation frequency to have the same value as the frequency of the reference signal in response to the error voltage.

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: A stereo/multivoice recording and reproducing apparatus used for a high fidelity video tape recorder comprises a multi-channel television system (MTS) decoder for demodulating stereo and multivoice signals included in an IF signal supplied from a tuner, a high fidelity audio processor for frequency-modulating the stereo signal output from a MTS decoder, left and right channel heads for recording the stereo signal frequency-modulated in the high fidelity audio processor, a second audio processor for amplifying the multivoice signal from the MTS decoder, and a third audio head for recording the multivoice signal amplified in the second audio processor. According to one aspect of the invention, the apparatus can simultaneously record stereo and multivoice signal and selectively reproduce one of the stereo signal and the multivoice signal.

Abstract: A positive direction current source is connected to a magnetic head coil via a multiplier and a switching device, and a negative direction current source is connected to the magnetic head coil via the switching device. The output current of the positive direction current source is controlled to a level appropriate for generating a magnetic field forming a magnet-optical recording mark based on the amplitude of an information signal by the multiplier. The switching device is turned on/off by a carrier signal. As a result, a magnetic head driving signal can be obtained having the positive direction current value modulated based on the amplitude of the information signal.

Abstract: A noise reduction apparatus wherein a sampled digital data is compared with a first threshold value (t) to average the digital data during a period while the level of low frequency components containing jitter noises is a predetermined threshold level or lower, an averaging operation for the digital data after a predetermined number of sampling points continues if a difference value between previously and presently obtained digital data takes a second threshold value (tp) or lower, the averaged digital data obtained during a predetermined number of rotations of a rotary head is converted into an analog signal, and the analog signal is subtracted from a reproduced signal.

Abstract: A video recorder for recording and reproducing video signals having a bandwidth with a limited upper transmission frequency, including HDTV signals. A recording signal processing circuit (14) with a first scanning circuit (10.1) for scanning the video signal to be recorded with first scanning recording pulses of a first scanning frequency that is at least equal to the limited upper transmission frequency, for providing the first recording signal (AS1), and a second scanning circuit (10.2) for scanning the video signal to be recorded with second scanning recording pulses that are displaced through half a cycle with respect to the first scanning pulses of the first scanning circuit (10.1), and having a second scanning frequency equal to the first scanning frequency, for providing the second recording signal (AS2). A recording/playback circuit (15, 16) includes recording-reproducing heads (11.1, 11.

Abstract: A recording mode discriminating circuit corresponding to reproduced signals of first and second recording modes in which a carrier frequency of frequency-modulated luminance signal becomes high and low includes a first bandpass filter using an upper side band wave frequency of the first recording mode as a central frequency thereof, a second bandpass filter using a predetermined carrier frequency of the second recording mode as a central frequency thereof, a discharge control circuit for flowing or interrupting a current of a first predetermined value in response to the presence or absence of the first bandpass filter when the reproduced signals are supplied, a charge and discharge control circuit for flowing or interrupting a current of a second predetermined value smaller than the first predetermined value in response to the presence or absence of the output of the second bandpass filter, and a capacitor commonly connected to the discharging circuit and the charging and discharging circuit, wherein the reco

Abstract: In a magnetic tape readback system for a multi-track tape player, a phase lock loop is provided for each of the channel circuits used for reading signals from the respective tracks on a multi-track tape. A common frequency determining capacitor is coupled to all of the phase lock loops such that the frequency of operation of the phase lock loops is stabilized. The capacitor has a capacitance usable in the individual phase lock loops for determining a frequency of operation and it is commonly AC connected to all of the phase lock loops. A capacitance AC couples and DC blocks each of the individual phase lock loops to the frequency determining capacitor such that the individual phase lock loops have their own reference DC levels and yet receive AC input from all of the other phase lock loops.

Abstract: An FM signal which is partly missing zero crossing points is supplied to an input terminal, to which a second polarity discriminating circuit and a lower side band suppressing circuit followed by a first polarity discriminating circuit are coupled together. A pulse extracting circuit receives the outputs of the first polarity discriminating circuit and a second polarity discriminating circuit to produce pulses corresponding only to portions of the FM signal at which the zero crossing points are absent. The pulses thus obtained are subsequently combined in a waveform reforming circuits with the FM signal from the input terminal, thereby permitting the FM signal to regain the zero crossing points.

Abstract: A signal processor is arranged such that, after an input signal is converted in such a manner that a first high-frequency component is relatively attenuated more than a low-frequency component by a predetermined amount as compared with a state before the input of the signal, a second high-frequency component which is different from the first high-frequency component is amplified, thereby reducing a noise component without exerting an adverse effect on the signal.

Abstract: An FM modulator includes a base clock generating circuit (7) receiving an incoming video signal for generating an AFC reference frequency signal having a frequency and phase corresponding to a horizontal synchronizing signal of the incoming video signal, a first carrier reset pulse having the same frequency as the horizontal synchronizing signal and a second carrier reset pulse whose frequency is an integer mutliple of that of the horizontal synchronizing signal. The second reset pulse is generated at a timing speed lagged behind the first reset pulse. The FM modulator further includes an adder (3) for adding the first reset pulse to the incoming video signal for lowering the DC level at the leading edge portion of the horizontal synchronizing signal, and an oscillator (9, 9a, 9b, 10, 10a, 10b) whose oscillation frequency is changed dependent on the DC level of the output signal from the adder to produce a carrier FM modulated by the video signal. The oscillator is reset by the second reset pulse.

Abstract: In order to reduce the disturbances caused by the head switch in a videotape recorder, in an arrangement for demodulating an FM modulated signal, a fixed value in the hold circuit used for maintaining the fixed value for the signal during the head switch, is selected such that it is situated at a value the interpolated signal would have had during the head switch time interval (T.sub.1) at an instant situated between 0.3 T.sub.1 and 0.8 T.sub.1 in the head switch interval. This may be realized with a delay unit which realizes a delay T.sub.v for which holds: 0.3 T.sub.1 <T.sub.v <0.8 T.sub.1.

Abstract: A digital signal magnetic recording/reproducing apparatus modulates a digital signal with a carrier and performs recording/reproducing of the modulated signal. The carrier frequency is made equal to the clock frequency multiplied by a factor (N/M), where N and M are integers. The carrier and clock are reproduced using only one phase locked loop. When the carrier-modulated signal is recorded/reproduced using a magnetic recording medium, the phase of the modulated signal is shifted relative to the phase of the carrier. Shifting the clock phase before using the clock for decoding the demodulated signal prevents a degradation of error rate. By periodically inserting a clock phase reference signal in the recording signal, accuracy of adjustment of clock phase is improved.

Abstract: A reproducing apparatus which is provided with: frequency converting means for performing frequency conversion of the FM regenerative signals respectively from the read heads, on the basis of frequency conversion signals each having a frequency different from the frequency of the carrier; voltage-controlled oscillators for generating the frequency conversion signals, respectively; phase comparators for comparing phases of two FM regenerative signals frequency-converted by the frequency converting means in the overlap period so as to produce a difference signal corresponding to the difference between the phases; switching circuits for feeding the difference signal generated by the phase comparators, into one of the voltage-controlled oscillators generating the frequency conversion signal for frequency conversion of succeedingly reproduced one of the FM regenerative signals in the overlap period; and loop filters for stabilizing a loop system constituted by the aforementioned parts; whereby the phases of two fr

Abstract: A circuit arrangement which includes an FM demodulator having a delay circuit which subjects the received FM signal to a preset time delay and a signal combining circuit which combines the delayed and undelayed FM signal to derive a combined signal the mean value of which is proportional to the frequency of the FM signal. A low pass filter derives the demodulated signal from such combined signal. The proportionality factor is determined by the preset time delay, which is controllable by a control signal supplied to the delay circuit by a datum level detector which detects a selected datum level of the demodulated signal; for example, the lowest level of such signal. By controlling the time delay in accordance with such datum level, the datum level detector thereby stabilizes the maximum amplitude of the demodulated signal relative to the datum level thereof despite variations in the maximum frequency swing of the received FM signal.

Abstract: In a frequency modulation system, a modulating signal is split into its low-frequency and high-frequency components. The low frequency component is used to modulate a carrier signal by conventional means in a first circuit and the low- and high-frequency components are used to narrowband modulate the carrier signal in a second circuit. The outputs of the first and second circuits are combined to provide a frequency modulated signal. The modulating and carrier signals can be binary-coded signals.

Abstract: A frequency demodulation circuit superposes pulses on an input frequency-modulated (FM) signal at substantially the peaks of the FM signal before demodulating the FM signal so that zero cross points of the FM signal can be correctly restored. A peak detection circuit detects peaks of the FM signal or peaks of the fundamental wave of the FM signal, which substantially correspond to the peaks of the FM signal. A pulse generating circuit generates, from the peak detection result, pulses respectively occurring at the same timings as those of the detected peak occurrance timings. The generated pulses are added to the FM signal to obtain the pulse-superposed FM signal.

Abstract: A frequency demodulation circuit disclosed superposes pulses on an input frequency-modulated (FM) signal at substantially peaks of the FM signal before demodulating the FM signal so that zero cross points of the FM signal can be correctly restored. A peak detection circuit detects peaks of the FM signal or peaks of the fundamental wave of the FM signal, which substantially correspond to the peaks of the FM signal. A pulse generating circuit generates, from the peak detection result, a train of pulses respectively occurring at the same timings as those of the detected peak occurrance timings. The generated train of pulses and the FM signal are respectively fed to differential inputs of a differential input type limiter. An output signal of the limiter is fed to a pulse count circuit to obtain a frequency demodulated signal.

Abstract: An information signal recording apparatus for recording an information signal having a predetermined frequency band onto a recording medium, which comprises signal separating means for receiving said information signal and for separating the received information signal into a first signal having a first frequency band and a second signal having a second frequency band which is higher than said first frequency band and outputting said first and second signals; first recording means for forming a frequency-modulated first signal by frequency-modulating the first signal outputted from said signal separating means and for recording said frequency-modulated first signal onto a first area of said recording medium; and second recording means for forming a frequency-modulated second signal, which is interleaved relatively to said frequency-modulated first signal, by frequency-modulating the second signal outputted from said signal separating means and for recording said frequency-modulated second signal onto a second

Abstract: A circuit for generating frequency-modulated signals for data to be recorded on magnetic tape has a converter to produce a control current I.sub.c for a capacitor C. A detection logic circuit senses voltage V.sub.c across the capacitor C and generates an appropriate frequency f which is fed to a charge pump, for discharging of capacitor C by a predetermined amount at a rate dependent on the frequency f. Control current I.sub.c then charges capacitor C again and the cycle is repeated. A starter circuit is also provided to ensure that the circuit oscillates on each cycle.

Abstract: In order to reduce disturbances in a device for demodulating a frequency-modulated signal, which disturbances are caused by head-switching in a video recorder, a low-pass filter which is normally arranged between the demodulator (10) and the hold circuit (12) is relocated. The low-pass filter (23, 24), i.e. at least the capacitive element (24) of this filter, is arranged in the hold circuit (12), and, in particular, at least the capacitive element (24) of the low-pass filter (23, 24) being arranged in the main signal path after the switching means (18).

Abstract: In a video signal recording/reproducing apparatus for recording and reproducing two-channel component signals, input two-channel component signals are processed separately from each other by two recording signal processing circuits to be recordable two-channel component signals. The recordable two-channel component signals are exchanged at predetermined intervals by a first switching circuit to be two combined signal each containing the recordable two-channel component signals which appear at periods corresponding to the exchanging invervals. The two combined signals are recorded on a recording medium via recording heads and reproduced from the recording medium via reproducing heads. The reproduced two combined signals are exchanged at the predetermined intervals by a second switching circuit to be the recordable two-channel component signals, which are thereafter processed separately from each other by two reproduced signal processing circuit to be the original two-channel component signals.

Abstract: A frequency demodulator includes an analog-to-digital converter for converting an inputted FM signal into a digital signal. A 90.degree. phase shifter is used to phase shift the converted digital signal. The phase shifted signal and the converted signal are utilized to determine the results of tan.sup.-1 (X/Y). X represents the converted signal, and Y represents the phase shifted signal. The result from the calculation is delayed for a period of time equal to one sampling cycle. The frequency demodulator also includes a subtractor for subtracting the delayed signal from the calculation result. A discontinuity corrector corrects any discontinuity in an output from the subtractor, and a reversal phenomenon compensator compensates the output from the discontinuity corrector when the output from the discontinuity corrector exceeds a predetermined range of levels. These levels correspond to an appearance of discrete lines of black or white color on a reproduced picture.

Abstract: In order to record audio signals on a magnetic record carrier, there is produced a high frequency pulsed signal which contains the low frequency information pertinent to the audio signal. This high frequency pulsed signal is produced in a manner such as to be substantially free of any signal component which has a frequency lying in the frequency range of the low frequency audio signal. As a result, cross-talk produced during recording on a plurality of tracks can be substantially reduced.

Abstract: In a magnetic recording and reproducing apparatus in which a frequency-modulated video signal and a frequency-modulated audio signal are frequency-multiplexed and the frequency-multiplexed signal is recorded on video tracks of a magnetic tape, and the recorded signal is reproduced, a noise produced in the audio signal due to video track switching in the signal reproduction is eliminated by holding the audio signal for a period of noise duration.

Abstract: A frequency modulating circuit comprising a circuit for separating a synchronizing signal from an input signal, a circuit for generating a sampling pulse in accordance with the synchronizing signal, a circuit for producing a frequency modulated signal out of the input signal, and a circuit for detecting the phase of the frequency modulated signal at the timing of the sampling pulse. The level of the input signal is corrected in accordance with the output of the detecting circuit, so that the phase of the frequency modulated signal is locked to a predetermined phase at the timing of the sampling pulse. Consequently, despite frequency modulation of the wide-band input signal, the invention is capable of preventing occurrence of any moire pattern that may otherwise be caused in displaying the demodulated signal.

Abstract: A magnetic tape recording/reproducing apparatus for recording video signals on a magnetic tape without providing a guard band between each two adjacent signal tracks. The apparatus comprises a first switching circuit for exchanging 2-channel component signals every nH period to obtain two combined signals each composed of the 2-channel signals which alternate every nH period, two modulators for modulating the two combined signals, a head section having two pairs of rotarty magnetic heads for recording the modulated signals on the magnetic tape so that each two adjacent blocks contain a same channel component signal and for reproducing the recorded signals from the magnetic tape, two demodulators for demodulating the reproduced signals, and a second switching circuit for exchanging the demodulated signals every nH to obtain the 2-channel component signals. With this arrangement, the recording density is remarkably increased and the cross talk interference hardly occur.

Abstract: A self-biased magnetoresistive reproduce head is excited with an a.c. sense current which simultaneously a.c. biases the magnetoresistive element. When reproducing a pre-recorded signal, the spectrum of the head output includes sidebands containing the signal information associated with a suppressed carrier at twice the bias frequency. These sidebands are far removed in the head output frequency spectrum from sources of low frequency noise. The invention teaches demodulating these sidebands by means of a locally generated carrier corresponding to the suppressed carrier which has a frequency of twice the bias frequency. This locally generated carrier is coherent with the bias frequency source. The information signal is thereby recovered in a portion of the spectrum immune from the effects of low frequency interfering noise.

Abstract: In a recording and reproducing apparatus wherein a video signal and an audio signal are recorded on the same recording track, a signal subjected to a quadrature differential PSK modulation with PCM audio signal is generated as an audio recording signal. The audio recording signal is disposed between occupied bands of FM luminance signal and down converted chrominance signal in a video recording signal and also recorded on a track where the video recording signal is to be recorded.

Abstract: In a recording apparatus frequency modulators (25-28) are provided for carriers having different frequencies with an information signal. The different frequency carriers are sequentially combined by a switch (12) and applied to a recording head in response to the head being shifted from one track to the next to record each of the carriers on a different track, so that there is a difference in frequency between carriers recorded on adjacent tracks. During playback, the frequency-modulated carriers are sequentially reproduced and separated by band-pass filters (25-24) into individual carriers, frequency-demodulated respectively by demodulators (29-32) and sequentially combined by a switch (33) to form the original information signal. Tracking control circuit (100) is provided to control the lateral position of the transducer head in response to the carriers which are derived from tracks on opposite sides of the track being scanned.

Abstract: Excessive cross talk between adjacent tracks can occur in a video recorder in which the line-synchronization pulses of adjacent tracks are not adjacent, in long-play or 8-mm video for example. The BAS signal is in accordance with the invention pole-reversed from track to track during recording when the video carrier is frequency-modulated in such a way that the level of the synchronization pulse corresponds alternately to the low and to the high frequency of the video carrier.

Abstract: An apparatus for detecting and compensating for the drop-out in a video tape recorder in which an FM audio signal is recorded on a magnetic tape and is reproduced therefrom utilizing a rotary magnetic head. In a playback mode, a frequency demodulator demodulates the reproduced FM audio signal. The reproduced FM audio signal is supplied to a synchronous detector and synchronously detected with an output signal of the frequency demodulator. An output signal of the synchronous detector is supplied through an integrator to a drop-out discriminator which detects a drop-out generating period and provides an output indicative thereof.

Abstract: A video signal recording and reproducing apparatus in which the luminance signal of a color video signal is frequency-modulated for recording and a reproduction frequency-modulated signal is frequency-demodulated to produce a reproduction video signal. A high frequency component is separated from the reproduction video signal and applied to a slice circuit comprising nonlinear elements including, for example, diodes connected in parallel with reverse polarities, thus eliminating noise at the low frequency signals included in the high frequency component. The apparatus further comprises a device for subtracting the sliced signal and the reproduced video signal one from the other in such a manner that the two signals are in phase with each other substantially at the desired ratio and in a predetermined frequency band.

Abstract: A capacitance element includes as an interelectrode substance a magnetic body for detecting a magnetic field formed by a magnetic recording medium. A tuned circuit includes the capacitance element as a tuning element and receives a signal from a high-frequency oscillator. The magnetic characteristics of the magnetic body change with changes in the magnetic field formed by the magnetic recording medium. The high-frequency signal output from the tuned circuit changes with changes in the magnetic characteristics of the magnetic body. A detecting circuit detects the changes in the high-frequency signal output so as to reproduce signals recorded on the magnetic recording medium.

Abstract: In an effort to provide exceptionally high resolution playback of video information recorded in the environment of an electronic still camera, the invention calls for:(a) Use of double side band FM recording, which in the prior art would have been productive of playback interference between the side bands of harmonics and the side bands of corresponding fundamentals unless the relative head-to-media speed was high enough to accommodate high carrier frequencies.(b) Bias recording such FM video information, thereby to prevent the inherent production of harmonic information within the media.(c) Up-converting the harmonic-free playback signal, before the harmonic-causing procedure of amplitude-limiting such playback signal, thereby to cause such signal to have a spectrum-wise wide disparity between the modulated fundamental in question and its harmonics, as caused by such amplitude limiting.(d) Removing the generated harmonics (and their side bands) prior to or during demodulation of the modulated fundamental.

Abstract: A method for recording high frequency signals representing data with simultaneous readout of low frequency information, such as servo information prerecorded on a magnetic disk, comprises the step of modulating with the data a carrier signal having a repetition frequency displaced significantly from the baseband of the data. The nonlinearity of the recording channel converts the modulated signal spectrum into the low frequency baseband so that the data is magnetically recorded while the low frequency prerecorded information is read out.

Abstract: A transmission system, which includes a recorder/reproducer with at least one frequency incapable of producing an output other than a direct current component and which transmits information in a frequency higher than the frequency incapable of producing an output, has an information recording and reproducing apparatus wherein a transformation circuit transforms a first data sequence including the information into a second data sequence, in accordance with frequency characteristics of the transformation circuit, which second data sequence can then be transmitted, and wherein a restoring circuit restores the first data sequence from a third data sequence obtained after transmission.