[EMAIL PROTECTED] wrote:
>
> * [EMAIL PROTECTED] (Romain Kang) on Mon, 03 Apr 2000
> | Comparing coaxial and Toslink, there is actually a measurable
> | difference between what you get at the other end of the line. The
> | archives of rec.audio.pro have discussions of this phenomenon, though
> | it's been a number of years since I've kept up with this subject.
>
> If it were an analog signal, it would matter. But whether a "1" has an
> intensity of X or several times X does not change its value one bit :).
>
> | The issue is "transport jitter", where the timing between the bits
> | varies by some amount (in the range of 5 to 500 picoseconds, if memory
> | serves).
>
> Which is compensated by the error correction inherent in the protocol and
> the data buffering in the receiver. A string of 16 bits is a string of 16
> bits, period.
>
> In other words, the "audiophiles" are hearing what they want to hear, not
> what is really getting to their ears.
Sorry "Rat", but you're wrong.
I agree that bits are bits. But coax and TosLink don't do error-correction since
the S/PDIF protocol doesn't do error-correction.
I agree that for recording, it doesn't matter that there is jitter.
But before we go any further, I think it's time to explain 'what is jitter'.
Jitter is an effect that is caused by the fact that the interval between the
samples varies a little. This variation isn't constant. Ie, consider a series of
samples: T1, T2, T3 and T4. Let's say they where recorded at 0, 1, 2 and 3
seconds. The value of T1, T2, T3 and T4 equals 1, -1, 1, -1. Ie:
1 @ 0.0
-1 @ 1.0
1 @ 2.0
-1 @ 3.0
So lets play them back. But with some jitter introduced of -0.1 +0.1 +0.1 -0.1.
Thus,
1 @ -0.1
-1 @ 1.1
1 @ 2.1
-1 @ 2.9
I think you agree that this series of bits represents another waveform. That's
what we call jitter!
Cheers,
Ralph
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