HDMI cable quality requirements , lol

[Modelworks]

Most here know about the monster cable price rip-offs and the over priced high end cables that are advertised. This past weekend I had to do something unthinkable to the 'must spend $100 on a cable' crowd. I was helping someone set up a projector for a presentation they had to do and during the process asked him for the HDMI cables, he handed them to me and they were the wrong cables. There were several different cables laying about and the ones that were brought were 2- 10 ft cables instead of the one 25ft. It was only about 30 minutes before the presentation started and no time to go and get the other cable and being a rural area there was no chance of buying one locally.

I pulled out my wire cutters and cut off one end of each cable to my friends horror. I then stripped back both cables about 6 inches and began twisting wire pairs together , covered each connection with a bit of tape and then taped the whole thing to the cable with another couple feet of tape, done, not pretty, but done. The cable worked fine, absolutely perfect , just like it were a $100 monster cable. No shielding in place between wires, no special gold solder, no careful routing of the wire pairs to avoid cross talk.

HDMI is a lot more forgiving than most realize. It does have error correction built in to the protocol so even the worst of cables are likely to work as long as you don't go so extreme with 100ft cables that cause a voltage drop, which any signal will have problems with, not just HDMI.

 

[sdifox]

post pictures :biggrin:

 

[Modelworks]

post pictures :biggrin:

done !

 

[sdifox]

now the important question. Are the copper crystaline structure properly aligned? :biggrin:

 

[queequeg99]

The trick in such an operation is using oxygen free electrical tape.

Seriously, though, this is a great real world example that purchasers of HDMI cables need to see to believe. I have typically recommended that people always get generic cables (monoprice, for example). And while I have typically recommended that they get high speed rather than standard speed cables (the cost difference is minimal in the generic market), in the vast majority of cases, standard speed cables will work (especially at distances of less than 10 feet).

Thanks for the post.

 

[JackBurton]

HDMI is a lot more forgiving than most realize. It does have error correction built in to the protocol so even the worst of cables are likely to work as long as you don't go so extreme with 100ft cables that cause a voltage drop, which any signal will have problems with, not just HDMI.

The HDMI standard does not include error correction.

 

[Exterous]

Screw HDMI I want my HDbaseT products

 

[Modelworks]

The HDMI standard does not include error correction.

Sure it does. It does it by lowering the differential swing .Whenever the receiver detects that bit errors are occurring the signaling is adjusted to correct those errors. There is also endpoint load adjusting where the impedance of the cable is adjusted to better match the transmission signaling. Where error correction fails is when the correction values exceed the range of the endpoints.

 

[Anarchist420]

Cables quality matters, but only to a certain degree. However, I'd never want to live in a house without lightning rods or without OFC copper wiring. Aluminum wiring isn't anygood because aluminum absorbs rather than transfers current.

 

[blackangst1]

Did you do any testing other than "the picture still looks nice"?

 

[Modelworks]

Did you do any testing other than "the picture still looks nice"?

Nope, none needed. The picture looked every bit as good as any other which is all that was needed.
I could connect up a vectorscope, connect up some eye pattern generators and do all the analysis if it mattered, but it doesn't. The cable worked perfectly.

 

[Modelworks]

Aluminum wiring isn't anygood because aluminum absorbs rather than transfers current.

The millions of feet of aluminum wiring in the world including the wiring connecting your house to the transformer from the power company isn't any good ? Rarely do you find a home or business that has its service connected to the utility with copper wiring. It cost too much at those sizes.

The main problem with aluminum wiring is oxidation, use the proper compound on it like the code states and it isn't an issue anymore. It heats up more than Cu but it is used quite a bit by utilities whenever cost are concerned.

 

[crashtestdummy]

Aluminum wiring isn't anygood because aluminum absorbs rather than transfers current.

This is one of the strangest statements I've ever heard. You either need to spend a lot more time studying physics, or a lot less.

 

[alcoholbob]

The only thing I care about is the termination end. All my Monoprice HDMI cables (about 6) have gone bad because either because the tang to wire connection couldn't handle the weight of the cable, or a bending the cable detached the wires.

Since then I always look at the termination end of an hdmi cable before I buy.

 

[Ross Ridge]

Sure it does. It does it by lowering the differential swing .Whenever the receiver detects that bit errors are occurring the signaling is adjusted to correct those errors. There is also endpoint load adjusting where the impedance of the cable is adjusted to better match the transmission signaling. Where error correction fails is when the correction values exceed the range of the endpoints.

There's nothing like this in the HDMI standard. There's a simple 8 bit to 10 bit encoding of the video data but this is for framing and overall DC balance.

You cable worked, not becasue any sort of error correction in the HDMI standard, but because your single splice in the cable wasn't enough to dramatically alter its integrity. You might run into problems if you happened to have particularly large source of noise near the splice, but otherwise I wouldn't have expected much problems.

 

[Modelworks]

The only thing I care about is the termination end. All my Monoprice HDMI cables (about 6) have gone bad because either because the tang to wire connection couldn't handle the weight of the cable, or a bending the cable detached the wires.

Since then I always look at the termination end of an hdmi cable before I buy.

You need to start doing what I have been doing for a long time, secure the cable with ties to something solid. I either use a screw if it is near something I can use one, or one of those adhesive attachments to support the cable. The HDMI connector design is really bad, it uses a heavy cable supported by next to nothing.
http://www.amazon.com/Command-17379-...ef=pd_sbs_op_5

 

[Modelworks]

There's nothing like this in the HDMI standard. There's a simple 8 bit to 10 bit encoding of the video data but this is for framing and overall DC balance.

There isn't in the HDMI standard for the data but there is in the LVDS system that it uses to send data and that is what matters here. The endpoints have to match impedance and swing when any cable is connected or the connection will fail. The endpoints are not dumb devices and actively adjust the voltages to prevent reflections that cause errors.

You cable worked, not becasue any sort of error correction in the HDMI standard, but because your single splice in the cable wasn't enough to dramatically alter its integrity. You might run into problems if you happened to have particularly large source of noise near the splice, but otherwise I wouldn't have expected much problems.

The cable worked because the endpoint was able to adjust for any differences in loss or interference across the pairs correcting any errors that might have resulted.

 

[Ross Ridge]

There isn't in the HDMI standard for the data but there is in the LVDS system that it uses to send data and that is what matters here. ...

HDMI uses TMDS signaling and the HDMI electrical specfication doesn't include anything resembling what you're talking about. While the TMDS signaling system is designed to prevent errors in the first place, it provides no means for detecting errors and then correcting them.

You didn't damage the cable enough to have a big effect on its ability transmit the signal. The twisted pairs are still more or less twisted at the splice point. It's not like you spliced in a smaller gauge of wire, created a cable with dramtically different twisted pair lengths, or introduced a noise source that could've actually caused problems.

 

[Modelworks]

HDMI uses TMDS signaling and the HDMI electrical specfication doesn't include anything resembling what you're talking about. While the TMDS signaling system is designed to prevent errors in the first place, it provides no means for detecting errors and then correcting them.

TMDS is nearly the same thing as LVDS and they use the same electrical components. It does provide a means of detecting errors. If the signal being sent lacks the proper parameters the endpoints adjust to compensate, doing so dynamically as needed. You seem to be ignoring the electrical part of the signaling system and focusing only on the digital bits. The electrical characteristics are more important than any other part of a communications protocol. Have you seen the capabilities of the endpoints now in use ?

automatically adjusts to skin-effect losses in copper cable.
four CML input buffers
loss-of-clock signal detector
three independent adaptive equalizers- Each channel analyzes the incoming signal and determines the amount of equalization to
apply.
four limiting amplifiers
four output buffers

You didn't damage the cable enough to have a big effect on its ability transmit the signal. The twisted pairs are still more or less twisted at the splice point. It's not like you spliced in a smaller gauge of wire, created a cable with dramtically different twisted pair lengths, or introduced a noise source that could've actually caused problems.

Meaning I stayed within the endpoint chipsets ability to compensate for changes in the cable. The same changes that vary from cable to cable that allows the communication to take place and adjust for errors in the transmission.

 

[Howard]

Cables quality matters, but only to a certain degree. However, I'd never want to live in a house without lightning rods or without OFC copper wiring. Aluminum wiring isn't anygood because aluminum absorbs rather than transfers current.

*facepalm*

 

[Ross Ridge]

TMDS is nearly the same thing as LVDS and they use the same electrical components. It does provide a means of detecting errors. If the signal being sent lacks the proper parameters the endpoints adjust to compensate, doing so dynamically as needed.

Neither LVDS or TMDS are designed to detect errors and correct them. They're designed to prevent them from occuring the first place. Everything you've described is just to prevent errors, not correct them.

You seem to be ignoring the electrical part of the signaling system and focusing only on the digital bits.

As I stated clearly, there's nothing in the HDMI electrical specificaiton to support your assertions. You're just making stuff up.

Meaning I stayed within the endpoint chipsets ability to compensate for changes in the cable.

No, meaing you probably stayed within the HDMI electrical specification's requirements of cables. Since nothing requires the cable to look pretty you could probably gotten it officially certified.

 

[BTA]

That picture is way worse looking that I imagined.

Which is great. I love it.

You should frame and mount it on the wall to show the world your awesomeness.