HDMI Cable query.

scotsbob

Not sure whether to ask here on on the Techie Forum.

Basically I need to know if a signal deteriorates with the length of cable?

For some strange reason my son wants to have a receiver and tv on opposite sides of his room. To keep things neat this will involve about 10 metres of HDMI cable. I can source the cable, but can anyone tell me if the signal will be seriously impaired over that distance.

BillTrac

I would not have thought there would be any degradation as it is a digital signal. You can get even longer HDMI cables so if there was a problem these would not be produced.

Also bear in mind you dont have to spend a fortune on a HDMI cable, again as it is a digital signal then either it works or it doesnt. Cable quality has no bearing

gjchester

BillTrac wrote: »

I would not have thought there would be any degradation as it is a digital signal. You can get even longer HDMI cables so if there was a problem these would not be produced.

Also bear in mind you dont have to spend a fortune on a HDMI cable, again as it is a digital signal then either it works or it doesnt. Cable quality has no bearing

The digitial signal won't deteriorate as an analog one will, but it can be affected, digital is all or nothing.

What will happen is that with a long or bad quality cable the ones and zeros may be degraded, as long as they are still identifiable they'll be fine. However is some cases the cables resistance may make it harder to tell them apart and the error correction in the recieving device may have to work harder to check the incoming digital info and that can lead to errors.

ie lets say a 0 is 0V and a 1 is 1mV, if the signal is degraded so a 1 drops to 0.5mV does the error correction see it as a 0 or a 1, when the error correction tries to correct it it may get it wrong leading to image problems.

Cable quality HAS a lot of bearing. Buying more expensive cables means better purity, lower resistance and potentially longer runs. It also depends on the error correction in the recieving device, the better that is the better it can cope with a recovering a degraded pulse.

Inactive

gjchester wrote: »

Cable quality HAS a lot of bearing. Buying more expensive cables means better purity, lower resistance and potentially longer runs.

It usually means wasting money on something that gives no real benefit.;)

Why should paying more equate to better quality anyway?

gjchester

Inactive wrote: »

Why should paying more equate to better quality anyway?

Dunno, maybe the cost of refining the cable from 99% pure to 99.9% TO 99.999999% pure, could be the cost of clean enviroments to manufacture the cable and the cost of using correctly spec'ed cable in the first place come into it.

You would not use bellwire to wire a mains plug to your PC, you use decent flex up to the job but when it comes to AV cables people almost always go for the cheapest option, and the "it's digital it's perfect" argument gets trotted out. I'm not avocating spending a fortune, just don't buy bargain basement.

Inactive

gjchester wrote: »

You would not use bellwire to wire a mains plug to your PC, you use decent flex up to the job but when it comes to AV cables people almost always go for the cheapest option, and the "it's digital it's perfect" argument gets trotted out. I'm not avocating spending a fortune, just don't buy bargain basement.

Not a like for like comparison I'm afraid, a HDMI cable will either work, or it will not, however much you pay for it.

gjchester

Inactive wrote: »

Not a like for like comparison I'm afraid, a HDMI cable will either work, or it will not, however much you pay for it.

No it's not but if you get a cable at 99p you can be sure they are not going to be spending much on components. Spend more and you'll get better wirin in the cables.

I'm not saying that the many frankly OTT claims by wire makers are all valid, but the components parts will be better. As you get longer cables attenuation starts to be an issue, and as I said it doesn't degrade the ones and zero's as such but can affect the ability of the recieving equpment to distinguish between them.

Inactive

gjchester wrote: »

No it's not but if you get a cable at 99p you can be sure they are not going to be spending much on components. Spend more and you'll get better wirin in the cables.

I'm not saying that the many frankly OTT claims by wire makers are all valid, but the components parts will be better. As you get longer cables attenuation starts to be an issue, and as I said it doesn't degrade the ones and zero's as such but can affect the ability of the recieving equpment to distinguish between them.

Just going around in circles, a digital cable will either work, or it will not, doesn't make any difference how much you spend on it.

Spending more does not equate to getting better.

gjchester

Inactive wrote: »

Just going around in circles, a digital cable will either work, or it will not, doesn't make any difference how much you spend on it.

There is no such thing as a digital cable, all cables use a voltage difference to convey a signal, regardless of if the signal is digital or analog.

The cable can degrade the voltage difference and the error correction in the recieving box can recover some or all of the signal so you'll get a signal just a degraded one, it's not as simple as it will or will not work.

The issue isn't about how much you spend, the issue is using the right spec cable for the job, not just whatever is lying around in the factory when they made it.

pogofish

10m will be fine for HDMI IME.

Don't waste your money on those super expensive cables - Most are a total rip-off.

Fifer

Would this be a bad time to mention jitter?