Posted by G-squared on 11/10/06 06:02

Matthew L. Martin wrote:
> Randy Yates wrote:
> > Tom Stiller <tomstiller@comcast.net> writes:
> >
<snip 'guest'>
>
> > Actually, it can. I'll have to back-peddle a little here.
> >
> > S/PDIF is a single-wire interface that embeds the clock with the
data.
> > Because of this, problems with the interface that aren't serious
> > enough to cause bit errors can still affect the sound by affecting
the
> > quality of the recovered clock. A PLL is used to recover the
clock,
> > and depending on the type of loop filter used in the PLL, input
noise
> > from cable degradations could introduce jitter into the digital
clock
> > and thus the reconstructed analog signal.
> >
> > How audible is it? That is a whole dissertation unto its own.
>
> According to test I did years ago when I had access to the proper
> equipment the jitter induced sidebands on an impaired cable were
85dB
> below the program material (CD test tones). One golden eared guy
> duplicated my results with similar equipment, but he claimed he
could
> hear 85dB below the program material, so the jitter was audible to
him.
>
> Matthew

Matthew, on your jitter tests, did the hardware have the PLL clock
recovery Stiller mentions ? If so, was there any way to monitor the PLL
error signal to see any relation to the jitter sideband issue ? Should
we expect more recent hardware to behave better and if so, how much
better in your estimation ? Just curious and thanks

GG

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