Quote:
Originally Posted by jem
Of course eveyone knows that HDMI cables are digital and therefore only send ones and zeros. Unfortunately everyone is wrong. HDMI in common with all copper (and indeed wireless) signals are NOT digital, they actually carry an analogue waveform on which is superimposed a digital signal. In simple terms the voltages on the cables are constantly changing (hence analogue) if it's above a certain value then the receiving equipment interprets it as a 1 and if it's below that value then it's a 0.
Now the longer the cable, the more the signal degrades to the point when it's no longer possible to accurately distinguish between what should be 1s and 0s and at that point the picture will fail completely. Also timing the signals is absolutely crucial, if the timing slides out of tolerance again the signal collapses, at the high frequencies involved, the cable will act as an aerial radiating radio waves out and picking up interference. This is helped by twisting the pairs of wires in a particular way. Get the number of twists per meter wrong and again the signal can degrade faster than it should.
Bend the cable and one set of wires on the outside of the will stretch more than those on the inside. Bend it too much and the difference in length can (and does) cause timing errors. HDCP is particularly sensitive to this, if HDCP doesn't handshake properly (and it does it every two seconds) then you simply won't get a picture.
So we all need to go out any pay hundreds of pounds for cables? Well no. For most cases when we are only talking about a metre or so the tolerances in the cable specs are enough that any old £3 cable should work just fine. However I'd be tempted to pay a little more, say £10 or so to be a bit more reassured that the cable has been manufactured properly.
Certainly the two or three meter £200-£300 cables that you sometimes see for sale promising much better picture quality than a £20 cable are really taking the p**s but I just wanted to say that HDMI is actually a very complex system and the oft repeated, 'well it's digital so it either works or it doesn't; and a £2 cable is just as good as a £500 one' just isn't true. HDMI cable are NOT all the same but unless you are dealing with long lengths or are in a particularly noisy (electrically speaking) environment, you really don't have to go overboard.
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Well said,
I think I eventually got the same point over in this thread.
http://www.cableforum.co.uk/board/sh...php?t=33654072
I got my voice heard on pages three and four.
There really is some cr@p spouted on both side of the argument. For a domestic application I am convinced that it IS worth paying a bit more for a cable. I have set my budget at the £20 mark.
I have read some reports that HDMI devices can synchronise more slowly with a poor quality cable. If nothing else, better quality cables are gold plated which reduces oxidisation on the contacts. If you have paid say £700 for a 40" screen, £175 for a Bluray why not £20 for a cable. Thats before you start considering AV Amps and Surround Sound.
Well thats my two cents worth.
