Cable controversy: digital signals are just bits, but it does not mean that nothing can go wrong

Posted on Jan 2, 08 04:48 PM PDT

I have seen a lot of controversy about whether or not more expensive cables are worth their price, and the argument that comes often is that digital signal is just bits (0 and 1) and is therefore not degradable. And while I’m attempting to settle the “expensive versus cheap” cables debate, I would like to comment about this notion.

A digital signal is by nature more “resistant” to degradation, but it doesn’t mean that it is immune to degradation. With an increase in the length of the cable, and in the frequency (how fast the signal switches between 1 and 0), errors can be introduced, bits might be lost and sometimes error correction protocols might not be able to fix them. For a video signal, this might produce randomly blinking pixels (which would be more visible on a very large screen/projector), blocky corruption artifacts or plain black screen. However, it *cannot* produce a fuzzier image, like a “bad” analog cable might.

Random pixels, with a long HDMI cable (>12 yards). Click to zoom

Now, whether a cheap cable is “good enough” for you is a different question. My guess is that for most people, and over short distances, it should be good enough and the image should be identical to the one produced by a more expensive cable. If you are building a fancy home theater system with the cables in the walls, you should do a little more research… because of the length involved.

It is just useful to recognize that digital signals, especially high-bandwidth ones, can be corrupted, that’s why there is a maximum length (and frequency rating) for cables transporting a high-frequency digital signal like DVI or HDMI.

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