Circuit for tape duplication in video tape recorder

A method for reducing picture degradation during copying in a video tape recorder, comprising the steps of:

• amplifying a first signal detected at a first video head in a first amplifying step;
• controlling the gain of said first signal;
• filtering said first signal in a first filtering step;
• limiting said first signal, after said first filtering step to a first level for demodulation to produce a second signal;
• performing a second filtering operation on said first signal, after said first filtering step, to produce a third signal;
• demodulating the second signal and filtering the demodulated second signal;
• mixing said filtered demodulated second signal and said third signal for producing a fourth video signal;
• amplifying said first signal, after said first filtering step, prior to recording by a second video head in a second amplifying step;
• recording the amplified first signal;
• separating a synchronizing signal from said filtered demodulated second signal;
• producing a switching pulse from said separated synchronizing signal;
• and
• applying said switching pulse to said amplifying stage to allow channel switching of the amplified first signal.

A frequency modulation signal transfer-recording system of a video tape recorder, comprising:

• reproduction means for reproducing a program to be copied, comprising:
• first pre-amp means for amplifying a first signal received from a head on the video tape recorder;
• drop out detection means for determining if the first signal, amplified by said first pre-amp means, is below a certain level;
• delay means for compensating the first signal upon detection, by said drop out detection means, of the first signal being below said certain level;
• first switch means for connecting said first pre-amp means or said delay means to an automatic gain controller, based on the detection of a low signal;
• said automatic gain controller controlling the gain of the first signal or the compensated first signal to produce a gain controlled first signal;
• first filter means for filtering the gain controlled first signal for producing a filtered first signal;
• second filter means for separating a color signal contained in the first signal from the filtered first signal;
• limiter means for limiting the filtered first signal to a level suitable to demodulation;
• demodulator means for demodulating the limited first signal for producing a demodulated signal;
• a mixer for mixing the color signal separated from the first signal and the demodulated signal, producing a video signal;
• and
• synchronization separating means for generating a synchronization signal from the demodulated signal;
• and
• recording means for recording the reproduced program to be copied, comprising:
• high frequency compensation means for correcting the filtered first signal, from said first filter means, for
• recording through a second pre-amp means;
• second switch means for connecting said synchronization signal to a switching pulse means based on a mode of operation of the video tape recorder;
• and
• said switching pulse means generating a switching pulse used in channel switching during recording.

A method for reducing picture degradation during copying in a video tape recorder, comprising the steps of:

• amplifying a first signal detected at a first video head in a first amplifying step;
• controlling the gain of said first signal;
• filtering said first signal in a first filtering step;
• limiting said first signal, after said first filtering step, to a first level for demodulation to produce a second signal;
• performing a second filtering operation on said first signal, after said first filtering step, to produce a third signal;
• demodulating the second signal and filtering the demodulated second signal;
• mixing said filtered demodulated second signal and said third signal to produce a fourth video signal;
• amplifying said first signal, after said first filtering step, prior to recording by a second video head in a second amplifying step;
• recording the amplified first signal;
• separating a synchronizing signal from said filtered demodulated second signal;
• and
• producing a switching pulse from said separated synchronizing signal.

A frequency modulation signal transfer-recording system of a video tape recorder, comprising:

• reproduction means for reproducing a program to be copied, comprising:
• first pre-amp means for amplifying a first signal received from a head on the video tape recorder;
• drop out detection means for determining if the first signal, amplified by said first pre-amp means, is below a certain level;
• delay means for compensating the first signal upon detection, by said drop out detection means, of the first signal being below said certain level;
• first switch means for connecting one of said first pre-amp means and said delay means to an automatic gain controller, based on the detection of a low signal;
• said automatic gain controller controlling the gain of one of the first signal and the compensated first signal to produce a gain controlled first signal;
• first filter means for filtering the gain controlled first signal to produce a filtered first signal;
• second filter means for separating a color signal contained in the first signal from the filtered first signal;
• limiter means for limiting the filtered first signal to a level suitable to demodulation;
• demodulator means for demodulating the limited first signal for producing a demodulated signal;
• a mixer for mixing the color signal separated from the first signal and the demodulated signal, producing a video signal;
• and
• synchronization separating means for generating a synchronization signal from the demodulated signal;
• and
• recording means for recording the reproduced program to be copied, comprising:
• high frequency compensation means for correcting the filtered first signal, from said first filter means, and for recording said filtered first signal through a second pre-amp means;
• and
• second switch means for connecting said synchronization signal to a switching pulse means based on a mode of operation of the video tape
• recorder.

A circuit for duplicating a first video tape onto a second video tape without demodulation and modulation of luminance signals, said circuit comprising:

• means for reproducing frequency modulated luminance signals and low-band modulated color signals from said first video tape, and for providing said frequency modulated luminance signals and said low-band modulated color signals;
• and
• means for recording said frequency modulated luminance signals and said low-band modulated color signals provided by said reproducing means on said second video tape;
• wherein said frequency modulated luminance signals and said low-band modulated color signals reproduced from said first video tape are directly transferred to be recorded on said second video tape without frequency demodulation of said frequency modulated luminance signals.

A circuit for duplicating a first video tape onto a second video tape without demodulation and modulation of luminance signals, said circuit comprising:

• means for reproducing frequency modulated luminance signals and low-band modulated color signals from said first video tape, for providing said frequency modulated luminance signals and said low-band modulated color signals, and comprising:
• color reproducing means for generating demodulated color signals from said low-band modulated color signals,
• frequency demodulator and synchronization signal separating means for generating demodulated luminance signals by demodulating said frequency modulated luminance signals and for generating synchronization signals, and
• means for mixing said demodulated luminance signals with said demodulated color signals to provide a composite video signal as a video output for a video monitor;
• and
• means for recording said frequency modulated luminance signals and said low-band modulated color signals provided by said reproducing means on said second video tape;
• wherein said frequency modulated luminance signals and said low-band modulated color signals reproduced from said first video tape are directly transferred to be recorded on said second video tape without frequency demodulation of said frequency modulated luminance signals, said recording means comprising:
• means for generating vertical synchronization signals in response to said synchronization signals generated by said synchronization signal separating means,
• monostable multivibrator means for generating switching pulses in response to said vertical synchronization signals, and
• drum servo means for controlling rotation of a drum having record head means in response to said switching pulses, said record head means for recording said frequency modulated luminance signals and said low-band modulated color signals on said second video tape.

A method for duplicating a first video tape onto a second video tape in a video tape recorder without video signal demodulation, said method comprising:

• reproducing frequency modulated luminance signals and modulated color signals from said first video tape;
• providing said frequency modulated luminance signals and said modulated color signals on an transfer signal path to a recording section;
• receiving said frequency modulated luminance signals and said modulated color signals in said recording section;
• and
• recording said frequency modulated luminance signals and said modulated color signals on a second video tare in said recording section.