Post by orangeLollies on Apr 21, 2010 6:24:55 GMT -5
Hi Bill, fair call ...I guess my statement was based on the actual method used to pass the 1s and 0s over a medium. To my knowledge I thought if you were to view the optical and coax on a scope, the optical would show a perect square wave, whereas the coax (electircal signal) will show ramps and slight distortions in the wave pattern. Hense my 'true digital medium' statement. If what I'm saying is incorrect, please let me know, as I will have to do some more study to clear up my mis-information
In saying that, I guess computers move one's and zero's around all over the shop using electrical signals, so in hindsight, the 'normalsation' (if that's the correct term) of a electrical digital signal is obviously very well developed, as you have stated...
Although I do believe, with optical you can carry a digital signal much further, as it is not as prone to degredation and interferance as an electrical signal...
Keen to hear more of your thoughts... ;D
Wow, Shane, you've really gotten into this!
Yeah, I' enjoy some good brain candy... it drives my wife nutts though ;D
So, here's the thing, as with all things, I can prove it to you either way with math, and the answer is, it depends. It mostly depends on the quality of your equipment.
Essentially, optical is going to have the greater range of bad to good. The best optical is the best there is, and the worst optical is far worse than the worst copper. If you copper isn't up to snuff, it can still get things right mostly. If your optical is subpar, you're probably dead.
So, when you put it in terms of scoping it, if you're using a high quality optical receiver and medium, then it will look quite crisp, perfect on, perfect off. But, what if you have a low-cost laser that isn't quick on the switch? You could end up bleeding light when it's supposed to be off because the laser is still cooling its jets from the last time it was on. Or, if you have a low quality cable, or connector, you could have light spilling all over the place or bouncing back at you or just bouncing up and down between two small segments of the optical cable.
In terms of coax/copper, it's much more rugged. Of course, it can't possibly achieve the distances that high-quality optical ultimately can, but are you seriously interconnecting your DAC over 10,000 kilometers? I mean, I'd love to see the setup and all, but... ;D So, back to your scope, yes, you could see softness to the rigidity of the ones and zeroes. Copper isn't on/off, it's high/low. High is 1, low is 0. But, most of the time, we can tell if the signal should have been high or low, even if it wasn't perfectly peaked or valleyed (look, I made up a new adjectival form of valley!).
Back to the actual implementation, the question is, what are you doing with it? For our purposes, consumer electronics, the coax/copper solution works, in general, better than the optical. The optical is going to use the cheapest plastic-based optical cable the industry standards body can find along with the cheapest light sources they can ratify. It's all about cost. Rising and falling that coaxial digital signal is pretty easy now, even on plane old copper wire pairs getting stomped on in the living room by the kids playing McTendo's latest Sonic adventure.
Bill, thanks heaps for this insight. The optic quality, or lack of, in consumer grade components was not something I had considered, and your argument makes complete sense... More brain candy
Seeing that I dont have 10,000km of super optic cable, I'm now going to go replace my very short (and free) toslink cables with some good ol 75ohm digital coax copper ;D