Magnetic recording and/or reproducing system

Abstract

In reducing crosstalk between the low frequency, frequency-converted chrominance portions of h-aligned video signals on adjacent tracks, the frequency converting carrier, but not the entire frequency converted portion, has its polarity inverted at the end of each line interval during the recording of alternate tracks but not during the recording of the remaining alternate tracks. This eliminates the extraneous signal that would otherwise be produced in the balanced modulator of the playback apparatus by any direct voltage offset or transient remanent of a direct voltage offset in the recorded signal.

What is claimed is: 
     
       1. Apparatus in which video signals are recorded in h-alignment in adjacent tracks on a recording medium, said apparatus comprising: A. means for generating a frequency converting carrier signal in first and second versions of opposite polarity;   B. a frequency converter to receive chrominance components of said video signals; and   C. means to apply said first and second versions of said carrier signal in a predetermined sequence to said frequency converter, said sequence being such that, during alternate tracks, only one of said versions is applied and, during the remaining alternate tracks, said first and second versions are applied alternately in successive line intervals.   
     
     
       2. The apparatus of claim 1 in which said carrier generating means comprises: A. an oscillator to generate said carrier signal;   B. a double-throw switching circuit comprising first and second input terminals connected to receive said first and second versions of said carrier signal, said switching circuit comprising an output terminal that can be conductively connected to said first and second input terminals alternately; and   C. a filter connecting said output terminal of said switching circuit to said frequency converter.   
     
     
       3. The apparatus of claim 1 comprising: A. a low pass filter connected to said frequency converter; and   B. transducer means connected to said filter to record the frequency converted signals on said recording medium.   
     
     
       4. The apparatus of claim 3 comprising: A. a second frequency converter a connected to said means to apply said carrier signal, whereby said second converter receives said first and second versions in said predetermined sequence;   B. switching means to connect said transducer means alternatively to receive frequency converted signals from said first-named frequency converter and to supply reproduced signals from said recording medium to said second frequency converter; and   C. a comb filter connected to said second frequency converter to filter interleaved cross-talk components from desired, frequency converted chrominance signals of opposite polarity.   
     
     
       5. The apparatus of claim 1 comprising: A. reproducing transducer means to play back information recorded on said recording medium; and   B. a comb filter connected to said frequency converter to filter interleaved cross-talk components from desired, frequency converted chrominance signals of opposite polarity. .Iadd. 6. Apparatus in which video signals are recorded in adjacent tracks on a recording medium, said apparatus comprising:   A. means for generating a frequency converting carrier signal in first and second versions of opposite polarity;   B. a frequency converter to receive chrominance components of said video signals; and   C. means to apply said first and second versions of said carrier signal in a predetermined sequence to said frequency converter, said sequence being such that, during alternate tracks, only one of said versions is applied and, during remaining alternate tracks, said first and second versions are applied alternately in successive line intervals. .Iaddend..Iadd. 7. Apparatus for reproducing video signals that have been recorded in adjacent tracks on a recording medium with a carrier having one set of phase conditions line interval by line interval in alternate tracks and a different set of phase conditions line interval by line interval in the remaining alternate tracks, the phase conditions of carriers of the signals recorded in adjacent tracks being such as to create predetermined cross-talk relationships during reproduction, said apparatus comprising:   A. means to reproduce the signals recorded on each track and cross-talk signals from adjacent tracks;   B. means to shift the carrier frequency and phase condition of the reproduced signals for a line interval at a time; and   C. means to combine the resultant reproduced and revised signals and cross-talk signals with the reproduced and revised cross-talk signals of the next successive line interval to reduce the amplitude of said   
     
     
        cross-talk signals. .Iaddend..Iadd. 8.  The apparatus of claim 7 in which said means to combine comprises a comb filter that comprises an input terminal, an output terminal, and parallel signal paths joining said input terminal to said output terminal, one of said paths comprising delay means to delay the passage of signals therethrough by a period of time equal to one horizontal line interval. .Iaddend..Iadd. 9. Apparatus for recording video signals in adjacent tracks on a recording medium and for playing back the recorded signals, said apparatus comprising: A. means for generating a frequency converting carrier signal in first and second versions of opposite polarity;   B. a frequency converter to receive chrominance components of said video signals;   C. means to apply said first and second versions of said carrier signal to said frequency converter in a predetermined sequence such that, during the recording of alternate ones of said tracks, only one of said versions is utilized to frequency convert said chrominance components and, during the remaining alternate tracks, said first and second versions are utilized alternately for frequency converting successive line intervals;   D. means to record and reproduce said chrominance components line interval by line interval and track by track, said reproducing means also reproducing cross-talk chrominance signals from the next adjacent track;   E. means to reconvert the frequency of the reproduced carrier in the reproduced chrominance components by means of a carrier signal having the same frequency as said frequency converting carrier signal;   F. means to control the phase of said carrier applied to said frequency reconverter to correspond to said first and second versions of opposite polarity according to a predetermined sequence; and   G. a comb filter connected to the output of said frequency reconverter to filter out cross-talk components of the frequency reconverted signal. .Iaddend..Iadd. 10. Apparatus in which video signals are recorded in adjacent tracks on a recording medium, said apparatus comprising:   A. means for generating a frequency-converting carrier signal, the phase of which changes in a predetermined manner at predetermined line intervals;   B. a frequency converter to receive chrominance components of said video signals; and   C. means to apply said carrier signal to said frequency converter, the sequence of phase changes of said carrier signal being such that, during the recording of adjacent tracks, the relative phase of the carrier of the frequency converted signal has a predetermined relationship to the phase of the carrier of the adjacent recorded signal in the next adjacent track. .Iaddend..Iadd. 11. Apparatus in which video signals are recorded in adjacent tracks on a recording medium, said apparatus comprising:   A. means for generating a carrier signal the phase of which is changed in a predetermined manner at the end of certain horizontal line intervals;   B. means for changing the frequency and phase of chrominance components of said video signals in accordance with said carrier signal and to produce a frequency converted chrominance signal; and   C. transducer means for recording said frequency converted chrominance signal on said recording medium with a predetermined phase relationship to minimize interference during playback of said frequency converted chrominance signals recorded in adjacent tracks. .Iaddend..Iadd. 12. Apparatus in which video signals are recorded in adjacent tracks on a recording medium, said apparatus comprising:   A. a chrominance signal source for supplying a chrominance signal having a first carrier frequency;   B. a carrier signal source for supplying a carrier signal having a second frequency higher than said first frequency, the phase of said carrier signal being changed in a predetermined manner at the end of selected line intervals for cancellation of cross-talk between signals from adjacent tracks during reproduction of the recorded signals;   C. frequency converter means for changing the frequency of said chrominance signal to a third frequency corresponding to the difference between said first frequency and said second frequency in response to said carrier signal; and   D. recording head means for recording the frequency changed chrominance signals in adjacent tracks on said recording medium. .Iaddend..Iadd. 13. Apparatus for reproducing chrominance signal recorded in adjacent tracks on a recording medium, the recorded chrominance signals on adjacent tracks having different phase conditions, said apparatus comprising:   A. means for reproducing said recorded chrominance signals;   B. means for generating a carrier signal the phase condition of which is changed in response to the phase condition of the chrominance signal being reproduced;   C. means for frequency converting the reproduced chrominance signal in accordance with said carrier signal;   D. comb filter means; and   E. means for supplying said frequency converted chrominance signal to said comb filter means. .Iaddend..Iadd. 14. Apparatus for recording video signals in adjacent tracks on a recording medium and for reproducing said signals, said apparatus comprising:   A. a chrominance signal source for supplying a chrominance signal having a first carrier frequency;   B. a carrier signal source for supplying a frequency converting carrier having a second frequency higher than said first frequency, the phase of said frequency converting carrier signal being changed in a predetermined manner at the end of selected line intervals;   C. frequency converter means for changing the frequency of said chrominance signal to a third frequency corresponding to the difference between said first frequency and said second frequency in response to said frequency converting carrier signal as changed;   D. means for recording the frequency changed chrominance signal in adjacent tracks on said recording medium and for reproducing said recorded frequency changed chrominance signal;   E. means for generating a frequency reconverting carrier signal at said second frequency, the phase of said reconverting carrier signal being changed at the end of selected line intervals in a manner determined by said changed frequency converting carrier signal to cancel cross-talk between signals from adjacent tracks during reproducing of the recorded signals; and   F. comb filter means connected to receive the frequency reconverted chrominance signal to reduce the amplitude of undesired cross-talk signals therefrom. .Iaddend.