In article ,
Johnny B Good wrote:
Presumably, this change was implemented early on in readiness for
colour transmissions, perhaps to ease the final transition to a system
that could no longer be locked to the mains frequency.

It may have been to do with the increasing use of outside broadcasts and
so on as inserts to programmes. Think things like Nationwide. Where those
might use their own generator or battery supply. You could lock the studio
to a pulse generator anywhere, allowing pictures to be mixed between the
two. Terms like genlock and natlock were bandied about at the time. And of
course a VTR needs a stable 50 Hz reference too. Which mains simply isn't.

If a VTR is locked to mains, its playing time will vary with that mains
frequency. Not exactly ideal.

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*I speak fluent patriarchy but it's not my mother tongue

Dave Plowman London SW
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