System for recording and reproducing digital signals

Claim 2

A digital signal recording system comprising: pulse train supplying means for supplying a repetitive pulse train of a constant period; means for generating a first sawtooth wave of a phase and frequency coincident with those of said pulse train thus supplied; means for generating a second sawtooth wave delayed by 1/2 of said period from said pulse train thus supplied and having the opposite polarity relative to said first sawtooth wave; means for generating a data pulse train digitally coded by the presence or absence of pulses in accordance with data with a pulse train delayed by 1/4 period relative to said pulse train thus supplied as timing pulses; means for causing switching of said first and second sawtooth waves by said data pulse train thereby to obtain a composite sawtooth wave; and means for recording said composite sawtooth wave as a recording digital signal in one track on a recording medium, said composite sawtooth wave having a rising part coinciding with the phase and frequency of the pulse train of said constant period and a falling part coinciding with the phase and period of said data pulse train and having the information content of two digital signals of the pulses of said constant period and said data pulses.

Claim 3

A digital signal recording system according to claim 1 in which said pulse train supplying means comprises means for separating vertical synchronizing signals from video signals and means for forming said pulse train of constant period from said separated vertical synchronizing signal.

Claim 4

A reproducing system for reproducing digital signals recorded by the recording system according to claim 1, said reproducing system comprising: means for reproducing said comosite sawtooth wave recorded on said recording medium as pulses resulting from differentiation of the rising and falling parts thereof; means for separating according to polarity pulses of a polarity corresponding to said rising part and pulses of a polarity corresponding to the falling part of the pulse train from said reproducing means and resulting in separating said data pulses and said pulses of constant period; delay means for delaying said data pulses thus separated and said pulses of constant period; means for forming pulses for switching from the resulting output pulses of said delay means; means for obtaining pulses in accordance with data from said pulses for switching; means for gating said data pulses separated respectively by said pulses for switching or said pulses of constant period; means for forming timing pulses for use in restoring data from pulses in accordance with said data from pulses in accordance with said data and said data thus gated or pulses of constant period; and means for deriving as a control signal said pulses of constant period thus separated.

Claim 5

A digital signal reproducing sYstem according to claim 3 which further comprises a register for receiving as input said pulses in accordance with data and sending the same out in the direction opposite to that of the input, said reproducing means reproducing said composite sawtooth wave from said recording medium driven to travel in the direction reverse to that at the time of recording and deriving pulses of negative polarity in correspondence with the rising part of said composite sawtooth wave and pulses of positive polarity in correspondence with the falling part thereof.

Claim 6

A digital signal recording system comprising: pulse train supplying means for supplying a repetitive pulse train of a constant period interrelated with a vertical synchronizing signal of a video signal; a first flip-flop circuit for generating an output of a waveform having rising and falling parts for each pulse of said pulse train thus supplied; a first trigger pulse generator for differentiating the output waveform of said first flip-flop circuit and generating, at the rising part thereof, first trigger pulses of a frequency equal to 1/2 of that of said supplied pulses; a second trigger pulse generator for differentiating the output waveform of said first flip-flop circuit and generating second trigger pulses lagging by 1/2 period relative to said first trigger pulses at the falling part thereof; a first sawtooth generator operating in response to said first trigger pulses to generate a first sawtooth wave; a second sawtooth generator for generating a second sawtooth wave in response to said second trigger pulses; means for inverting the polarity of said second sawtooth wave; means for forming a first delay pulse of a period delayed relative to said first trigger pulses by 1/4 of the period thereof; means for forming a second delay pulse of a period delayed relative to said second trigger pulses by 1/4 of the period thereof; means for determining the presence or absence of output pulses from the pulse train of said second delay pulses in accordance with the data content and generating binary-coded data pulses; a second flip-flop circuit supplied with said first trigger pulses and said data pulses and respectively set and reset thereby to generate output rectangular waves; first gate means for gating said first sawtooth wave through the use of one output rectangular wave of said second flip-flop circuit; second gate means for gating said second sawtooth wave through the use of the other output rectangular wave of a polarity opposite that of said one output rectangular wave; mixer means for mixing the sawtooth waves thus gated by said first and second gate means and obtaining one continuous composite sawtooth wave; and recording means for recording said composite sawtooth wave in one track on a recording medium.

Claim 7

A digital signal recording system comprising: pulse train supplying means for supplying a repetitive pulse train of a constant period interrelated with a vertical synchronizing signal of a video signal; a first flip-flop circuit for generating an output of a waveform having rising and falling parts for each pulse of said pulse train thus supplied; a first trigger pulse generator for differentiating the output waveform of said first flip-flop circuit and generating, at the rising part thereof, first trigger pulses of a frequency equal to 1/2 of that of said supplied pulses; a second trigger pulse generator for differentiating the output waveform of said first flip-flop circuit and generating second trigger pulses lagging by 1/2 period relative to said first trigger pulses at the falling part thereof; a first sawtooth generator operating in response to said first trigger pulses to generate a first sawtooth wave; a second sawtooth generator for generating a second sawtooth wave in response to said second trigger pulses; means for inverting the polarity of said second sawtooth wave; means for forming a first delay pulse of a period delayed relative to said first trigger pulses by 1/4 of the period thereof; means for forming a second delay pulse of a period delayed relative to said second trigger pulses by 1/4 of the period thereof; means for determining the presence or absence of output pulses from the pulse train of said second delay pulses in accordance with the data content and generating binary-coded data pulses; a second flip-flop circuit supplied with said first trigger pulses and said data pulses and respectively set and reset thereby to generate output rectangular waves; first gate means for gating said first sawtooth wave through the use of one output rectangular wave of said second flip-flop circuit; second gate means for gating said second sawtooth wave through the use of the other output rectangular wave of a polarity opposite that of said one output rectangular wave; mixer means for mixing the sawtooth waves thus gated by said first and second gate means and obtaining one continuous composite sawtooth wave; and recording means for recording said composite sawtooth wave in one track on a recording medium.

Claim 8

A digital signal recording system according to claim 5 which further comprises a saturation-type recording amplifier means for accomplishing saturation amplification of the composite sawtooth wave obtained by said mixer means and supplying the resulting output signal to said recording means.

Claim 9

A digital signal recording system according to claim 5 which further comprises: a first constant-voltage source; third gate means for gating the voltage of said first constant-voltage source through the use of said one output rectangular wave of said second flip-flop circuit and adding the resulting output voltage to the output sawtooth wave of said first gate means; a second constant-voltage source; and fourth gate means for gating the voltage of said second constant-voltage source through the use of said other output rectangular wave of said second flip-flop circuit and adding the resulting output voltage to the output sawtooth wave of said second gate means.

Claim 10

A reproducing system for reproducing digital signals recorded by the recording system according to claim 5, said reproducing system comprising: means for reproducing said composite sawtooth wave recorded on said recording medium as pulses resulting from differentiation of the rising and falling parts thereof; means for separating by polarity pulses of positive polarity corresponding to said rising part and pulses of negative polarity corresponding to said falling part of the pulse train from said reproducing means and separating said pulse train of constant period and said data pulses; first and second delay means for delaying said data pulses and said pulses of constant period thus separated respectively by at least the width of said pulses; a third flip-flop circuit supplied respectively with output delay pulses of said first and second delay means, thereby being set and reset, and generating output rectangular waves; means for differentiating one of the output rectangular waves of said third flip-flop circuit, deriving positive polarity pulses thereof, and obtaining pulses in accordance with data; fifth gate means for gating said pulses of constant period through the use of the other output rectangular wave of a polarity opposite that of said one output rectangular wave of said third flip-flop circuit; sixth gate means for gating said separated data pulses through the use of said one output rectangular wave of said third flip-flop circuit; and seventh gate means for forming clock pulses from said pulses in accordance with date and said fifth or sixth gate means.