[time-nuts] femtosecond jitter anyone?

[Tom Van Baak]

> The incoming clock source (master house clock) to this box / design  
> of interest is in another rack mount box external to this design on  
> the other side of the room and is anywhere from 44.1kHz up to a 10MHz  
> Rubidium (see also http://www.antelopeaudio.com).  This clock source  
> on the other side of the room also drives other equipment to be in  
> synch for any framing on AES/EBU digital.

Can you comment more on the antelopeaudio box? I admit I know
little about high-end audio, but it seems clear to me that the several
companies that over the years have incorporated "atomic clocks"
into their digital audio work might be misguided; confusing what is
long-term accuracy with short-term stability.

Sure, the word "atomic clock" sounds really cool. But high-quality
OCXO typically have much better jitter and short-term stability than
the telecom-style Rb oscillators that are used by audio companies.
Or do I misunderstand?

It would seem to me that very low jitter (or phase noise out to, say,
100 kHz, or ADEV from, say 10 us) is much more important for
audio work than specifications about absolute frequency accuracy
or long-term drift (such as what telecom Rb oscillators offer).

Now if an audio company used surplus Sulzer, or FTS 1200, or
Oscilloquartz BVA oscillators in their design, or even H-masers,
well, that would make sense. But Rb? Something doesn't feel right
about this.

/tvb