Magnetic recording and reproduction with polarity inversion during alternate line periods

Claim 2

In a magnetic recording system for recording and reproducing electrical signals such as television signals including video information and horizontal and vertical sync signals over frequency range greater than the normal system capability, the combination of an input circuit adapted to receive signals to be recorded, an inverter connected to said input circuit, a switching circuit having inputs connected to said input circuit and to said inverter and an output over which either of said inputs is selectively available, a sync timing circuit keyed by said horizontal sync signals, a gate pulse generator keyed by said sync timing circuit and connected to regulate the rate of switching of said switching circuit to invert regular portions of the entire video signal, at a rate corresponding to the horizontal sync pulses, on the output from said switching circuit to said recording transducer, and a recording transducer connected to said switching circuit output to record the signals in alternately inverted and direct form on a magnetic recording media whereby essentially the lowest frequency recorded is the frequency of operation of said timing circuit.

Claim 3

A magnetic recording system as defined in claim 1, wherein said gate pulse generator is arranged to produce a constant switching output to said switching circuit at one-half half the repetition rate of the horizontal sync signals.

Claim 4

A magnetic recording system as defined in claim 2, further including a playback transducer for reproducing the signal recorded on said media, a second inverter receiving the output of said playback transducer, a second switching circuit having an output for transmitting a signal for reproduction and having inputs from said second inverter carrying the recorded signal as recorded and in inverted form, and a sync separator and timing circuit receiving the signal from said playback transducer and connected to drive said second switching circuit at the same switching frequency as said first switching circuit to reinvert those portions of the original siGnal which were inverted for recording purposes prior to reproduction.

Claim 5

The process of expanding the useful frequency span of a magnetic recording system beyond the normal span of about nine octaves to a span from DC to in excess of two megacycles, suitable for recording and reproducing a television signal, comprising: a. receiving a signal to be recorded and regularly inverting the signal at a frequency within the frequency range of the signal to be recorded and substantially below the highest frequency to be recorded to provide signals for recording in both inverted and noninverted form, b. generating a switching signal at a constant frequency within the normal span of the system, c. recording on a magnetic recording media alternatively from the inverted and noninverted signal sources using the switching signal to control which source is employed, d. reproducing the recorded signal, e. sensing the regular pattern of inversion in the reproduced signal, and f. employing the thus sensed inversion pattern to reinvert the inverted portions prior to use of the playback signal, whereby essentially the lowest frequency actually recorded is the frequency of the switching signal and the reproduced signal can include substantially lower and higher frequencies.

Claim 6

The process of expanding the useful frequency span of a magnetic recording system beyond the normal span of about nine octaves to a span from DC to in excess of two megacycles, suitable for recording and reproducing a television signal, comprising: a. receiving a signal to be recorded and regularly inverting the signal at a frequency within the frequency range of the signal to be recorded and substantially below the highest frequency to be recorded to provide signals for recording in both inverted and noninverted form, b. generating a switching signal at a constant frequency within the normal span of the system, c. recording on a magnetic recording media alternatively from the inverted and noninverted signal sources using the switching signal to control which source is employed, d. reproducing the recorded signal, e. sensing the regular pattern of inversion in the reproduced signal, and f. employing the thus sensed inversion pattern to reinvert the inverted portions prior to use of the playback signal, whereby essentially the lowest frequency actually recorded is the frequency of the switching signal and the reproduced signal can include substantially lower and higher frequencies.

Claim 7

The process defined in claim 4, wherein the signal to be recorded incorporates video and related signals varying from DC to over one megacycle, the switching signal of step (b) being at a rate corresponding to one-half the horizontal sync signals of the television signal, whereby video signals for successive lines are inverted with respect to preceding and succeeding lines, and vertical blanking signals are subdivided at the frequency of inversion corresponding to said switching signal.

Claim 8

The process of claim 5, including the step of employing the horizontal sync signals from the original video signal to key a constant frequency gate pulse generator controlling an inverter switching device for recording, sensing the recorded signal and reproducing therefrom a timing signal, and employing such timing signal to control the reinversion during playback of the recorded signal.