SPDIF waveform Analysis

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jkeny

Banned
2007-02-06 12:43 am
Dublin
Below are two scope shots of SPDIF output from the same device - the only difference between them is a better PS.

The better PS speeds up the rise/fall slope of the SPDIF waveform. About half way up the slope of the line is the decision point. I believe that the faster/steeper slope makes for a more accurate decision point with a better chance of it matching the timing of the decision point of the ADC recording & less variability between decision points. Any anomalies in this timing leads to jitter.

The one with the better PS also sounds better :)

USB power
An externally hosted image should be here but it was not working when we last tested it.


Better PS
An externally hosted image should be here but it was not working when we last tested it.


The first pic shows a kink on the slope, I believe - could this be the result of a reflection falling on & superimposing on the slope?
The ringing on the top of the waveform also seems to be tamed somewhat in the bottom pic.
What sort of explanation can be used to explain the speed up & this sort of change in the waveform based solely on better power - lower impedance, less noise?
 
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jkeny

Banned
2007-02-06 12:43 am
Dublin
This unit is also with SY for testing from the beginning of October but he hasn't been in a position to address it yet.

This should answer the accusation against me stated here http://www.diyaudio.com/forums/ever...easurements-show-not-show-14.html#post2267216 "However I doubt that any measurement will ever satisfy your needs. You appear not to be interested in proof at all, but something else entirely.....
You have been offered well reasoned help from very technically competent and friendly forum members which you have dismissed at every turn."
 
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