Phil Leigh wrote: > I'll try and post some pics later. The square wave had a notch (like > a "Z" on its side) in the upper "mark" line. It did look a bit > rounded - certainly not as sharp as the wave from my AF generator.I > guess I was just bit surprised since the sine wave looked perfect, > but of course a sine wave is rather easiser on the electronics!
I assume that the basic signal is just the PCM, with maybe some overhead. Since PCM is 1,411,200 bits/second its three orders of magnitude higher Hz than normal audio signals. The differing shapers are why engineers like to look at the result of a square wave. The common distortion is to round off the edges of the square wave, which means that the high frequency response is not keeping up. If its a Z shape with overshoot on the leading edge, which quickly plateaus and then has a roll off just before it drops, that indicates it may be under-damped. Tube gear usually shows some horribly mangled non-square things. But that is for the analog signal. I would expect the SPDIF to be fairly close, and more importantly, a bit of rounding or overshoot is not important, since digital signals are kinda zero or one. The shape of the square wave is not a big deal (tm). Of course, if you put it through some really long wire with the wrong impedance, I'd expect to see what goes in as a square wave come out as a sine wave. Or worse. -- Pat Farrell http://www.pfarrell.com/ _______________________________________________ audiophiles mailing list [email protected] http://lists.slimdevices.com/lists/listinfo/audiophiles
