Quote:
Originally Posted by NewVista
Yes, depends on TV, some H stability shake, needs slower time constant ?
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I had never thought about this before. So the spinning video disc has the same sort of timebase errors as video tape when no timebase correction is used?
Bending or jitter requires a "faster" or reduced time constant. Uncorrected timebase errors from VHS tape needs the reduced time constant horizontal AFC low pass filter so that the horizontal oscillator keeps step with the velocity errors.
I found it interesting to find that negative modulation for North American 525 line TV broadcast required a horizontal AFC circuit to help overcome false triggering with noise impulses whereas older British televisions receiving positive modulation 405 line transmissions did not. I suspect this was because the horizontal sync pulse was at the modulation envelope peak for 525 which made it more susceptible to noise? I recall weak British 405 reception on sets with horizontal AFC locked well under the noise.