Method and apparatus for tape speed override operation when recovering helical audio

A circuit for effecting tape speed override in a video tape recorder having an audio timebase corrector and a helical scanner for recovering helical audio data from a recorded tape, comprising:

• means for supplying the timebase corrector with a variable audio clock whose frequency is varied in response to a selected rate of tape speed override;
• means responsive to the variable audio clock for providing a digital signal indicative of a time window in the audio timebase corrector during which the recovered audio data are processed;
• means for adjusting to an angular position of the scanner in response to the digital signal;
• and
• means for locking a linear position of the recorded tape to the scanner angular position to provide a constant phase-locked condition therebetween at the selected rate of tape speed override.

A circuit for tape speed override in a video tape recorder having an audio timebase corrector, and a helical scanner which recovers helical audio data from a recorded tape via a controllable scan tracking head, comprising:

• means for modifying the recorded tape speed commensurate with a desired rate of tape speed override;
• means for maintaining a predetermined constant tape to scanner phase relationship which prevents the controllable scan tracking head from jumping from one track to another;
• and
• means for adjusting the speed of the scanner to maintain a preselected timing relationship between the scanner phase and the timebase corrector.

A circuit for effecting tape speed override in a video tape recorder having an audio signal processor with an audio timebase corrector, and a helical scanner for recovering helical audio data from a recorded tape, comprising:

• means for supplying a constant reference signal;
• means for supplying a rate signal indicative of a selected rate of tape speed override;
• oscillator means receiving the constant reference signal for generating a variable audio clock in response to said rate signal;
• a window set control circuit responsive to the variable audio clock for setting a time window in the audio timebase corrector;
• counter means responsive to the variable audio clock and to the scanner for providing a digital number indicative of the present timing relationship between the scanner and the timebase corrector;
• processor means for determining if the digital number represents a desired timing relationship between the scanner and the timebase corrector and for generating a digital value indicative of the timing relationship;
• scanner servo means for adjusting the scanner angular position in response to the digital value;
• and
• tape servo means including capstan means responsive to the scanner adjustment for maintaining the tape in a phase-locked condition with the scanner.