PAL/NTSC to 48Ksample rate

[martin griffith]

Just about to get my workshop up and running again after a couple of
years and I'm going to play with some digital audio, but I want to
eventually genlock to a "professional" video system, ie not a crap VHS
machine.

I can get a Elantec EL4585 PLL to generate 27MHz then use a BB
PLL1700 to generate the audio clock.
The ADC's also have their own PLL,( Alesis AL1101, not the greatest,
but adequate for majority things)
Three PLL's in series, sounds(sorry) like a disaster in the making
for the jitter dept.

Any other/sensible options

martin


"Facts are stupid things.." -- Reagan, '88

 

[Pooh Bear]

martin griffith wrote:

Just about to get my workshop up and running again after a couple of
years and I'm going to play with some digital audio, but I want to
eventually genlock to a "professional" video system, ie not a crap VHS
machine.

I can get a Elantec EL4585 PLL to generate 27MHz then use a BB
PLL1700 to generate the audio clock.
The ADC's also have their own PLL,( Alesis AL1101, not the greatest,
but adequate for majority things)
Three PLL's in series, sounds(sorry) like a disaster in the making
for the jitter dept.

Any other/sensible options

Production facilities use a central *wordclock* and sync everything to
that.

Only one PLL / device in the chain.


Graham

 

[Pooh Bear]

"Michael A. Terrell" wrote:

Pooh Bear wrote:

martin griffith wrote:

Just about to get my workshop up and running again after a couple of
years and I'm going to play with some digital audio, but I want to
eventually genlock to a "professional" video system, ie not a crap VHS
machine.

I can get a Elantec EL4585 PLL to generate 27MHz then use a BB
PLL1700 to generate the audio clock.
The ADC's also have their own PLL,( Alesis AL1101, not the greatest,
but adequate for majority things)
Three PLL's in series, sounds(sorry) like a disaster in the making
for the jitter dept.

Any other/sensible options

Production facilities use a central *wordclock* and sync everything to
that.

Only one PLL / device in the chain.

Graham

If you are referring to video production the proper term is "Sync
generator" or Master Sync generator" to provide a composite sync along
with separate vert, horiz, burst and other signals needed to sync all of
the other equipment. This is usually followed by a full set of DAs to
buffer the signals and give multiple outputs per signal. I've used
Grass Valley and Tektronix at different studios and TV stations over the
years. A neat early digital video manipulation system was the Squeeze
Zoom made by Vital Industries in Gainsville years ago. It filled a full
height relay rack, had a 1000 A 5 V power supply and needed three phase
208 to operate it.

Well... the original query was about audio clocking, but audio wordclock is
also synced to video in such applications.

This why you end up with slightly odd sample rates like 44.056kHz ( IIRC )
instead of 44.1 kHz in some applications.

And don't even start with 'drop frame' time code syncing !


Graham