> michael brown
> Sent: 06 April 2005 12:33
> To: Microcontroller discussion list - Public.
> Subject: Re: [EE] Using clock mechanisms (was High sleep current on

> Sure enough, they turn it on and off.  Seems like that would make it
> very difficult to use for a PLL reference.

Not if you use a very long time constant and only let the PLL work when
there is a carrier to work on... The bit of an anologue TV which detects the
colour sub-carrier works on a very short bit of subcarrier (colour burst - I
think it's about 10 cycles but it might be more than that) just after the
line sync pulse. The "burst locked oscilator" is good enough to keep in
phase with the original colour burst for the duration of the picture line.

> BTW, I was wrongly thinking that MSF was some kind of generic
> worldwide acronym for the time systems.  Funny, it's a callsign with
> M being a UK prefix and the SF randomly allocated making it very
> specific to the UK system.

I always took the SF to stand for 'Standard Frequency'. I doubt it was
random.

Cheers...Mike.

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