Re: why is jitter so difficult to deal with?

Digital Drive

Upsamplers, DACs, jitter, shakes and analogue withdrawals, this is it.

In Reply to: Re: why is jitter so difficult to deal with? posted by jpsulliv on December 26, 2002 at 12:34:53:

Here's my Take Two. I'll try to keep it shorter this time.
(1) I agree that timing errors WITHIN THE DAC are impossible to eliminate completely and that they are readily audible. This kind of jitter is indeed important.
(2) I can't yet see why small errors WITHIN THE SIGNAL ENTERING THE DAC, including all upstream jitter, are impossible -- or indeed even difficult -- to eliminate completely.
And yet people say their ears tell them (2) is wrong.
To see my reasoning behind (2), consider an RS-232 interface. Its analog input representing a digital signal is laden with jitter, slew irregularities, level irregularities, and so forth. And yet the computer manages to reconstruct the bitstream WITHOUT ERROR. It's a simple circuit, probably using an approach similar to what I described before.
It therefore follows from (2) that transport jitter is IRRELEVANT. Not 99.9%, but 100%.
And yet I must be wrong, because people have heard the difference. I'm looking for someone to explain to me why the transport-DAC interface is fundamentally more troublesome than, say, an RS-232 interface.
One possible explanation is that it's not jitter people are hearing, but rather a severly degraded signal that the DAC cannot reconstruct, resulting in dropped bits. For instance, ultra-long cables will result in too much noise, Toslink doesn't have the bandwidth for 192/24, etc.

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Follow Ups Full Thread

Topic - why is jitter so difficult to deal with? - CCollby 15:25:33 12/22/02 (6)

Re: why is jitter so difficult to deal with? - jpsulliv 12:34:53 12/26/02 (5)

Re: why is jitter so difficult to deal with? - C Colby 15:58:35 12/26/02 (4)

Jitter is not a data error - Dave I 17:55:12 12/26/02 (3)

still wondering... - C Colby 22:09:29 12/26/02 (2)

The problem is isolation - Dave I 23:33:05 12/26/02 (1)

I think I understand - C Colby 06:39:37 12/27/02 (0)

Follow Ups

Re: why is jitter so difficult to deal with? - C Colby 15:58:35 12/26/02 (4)

Jitter is not a data error - Dave I 17:55:12 12/26/02 (3)

still wondering... - C Colby 22:09:29 12/26/02 (2)

The problem is isolation - Dave I 23:33:05 12/26/02 (1)

I think I understand - C Colby 06:39:37 12/27/02 (0)

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