and then there are twinax cables.
Which, of course, are not coax. Controlling impedance and skew in twinax is just as difficult as in other twisted-pair cables.
The complaint here seems to be that twisted pair can't offer sufficiently constant impedance. There is Cat6 cable certified to 1000MHz, so citing Cat5 being certified to only 100MHz as evidence that twisted pair isn't adequate certainly is misleading if not outright fraudulent.
Oh, for goodness' sake. I didn't indicate that CAT5, or similar constructions, can't be used at higher bitrates and frequencies. In fact, I have said nothing negative about the use of CAT5, 6, etc. in network cabling. But this is a different application, and it works really quite badly.
I'd rather not pay test probe prices for HDMI cabling.
I don't know what you're talking about. I haven't suggested that the cable best suited for carrying HDMI must be costly. In fact, in about a month we'll be introducing our Belden bonded-pair HDMI cable; it will be demonstrably technically superior to anything currently on the market; and it will be cheaper than most of what's currently available. If the HDMI standard had been done using unbalanced coaxial lines, the cable would be less expensive still, and easier to make, to boot.
By quoting heresay from unidentified sources whose expertise is unknown and unconfirmable, you have totally failed to do that.
Oh, fine. David DeSmidt and Martin VanDeBurgt, both at Belden, would be two of the engineers who've remarked on the inappropriateness of the choice of coax.
As for your claim that you have not purposefully misled, are you saying that you are unaware that there are Cat5+ certifications well in excess of 100MHz? You do realize that GigE runs on twisted pair, right? You realize that Infiniband does, that 10GigE will, etc? SATA? SAS? Future PCI Express? It is a joke to suggest that twisted pair isn't up to the task, and anyone who claims to be expert yet says so deserves to have his motives questioned.
But again, I have not said twisted-pair can't be used in high-speed data applications. I have said it was a poor choice for HDMI, and I have stated my reasons. And those issues which I have pointed to, and for which coax would provide substantial relief, that is, skew and return loss, are in fact the major problems with getting HDMI to perform consistently over distance.
As for lack of error correction, that is not a twisted pair issue, and the design choice understood that the data stream was not critical in nature.
Error correction is not a twisted pair issue. But if you're not going to provide error correction, using cable with relatively poor impedance control is a good way to produce dropouts. Knowing that the signal would be run real-time and without error correction would guide a reasonable designer to the conclusion that control over impedance and timing were too critical to rely upon twisted pairs.
I disagree with your assertion that 50 foot runs are "very common".
And you are wrong. We sell a lot of 50-foot cables. And 45, 40, 35, and 30, as well. All of these lengths are very popular and are in common use, and it is a challenge to meet spec at these lengths.
Since when did HDMI ever promise to support the needs of your church users? What were they happily using before they were stabbed in the back by the false promises of twisted pair?
We have lots of customers who have run analog component video 200 feet or more with excellent results; they haven't even needed booster amps at those distances. Analog video is phenomenally robust; and digital video, designed right, would be more, not less, so.
What is the volume of equipment today offering 16 bit 1080p?
Zero. But the standard calls for it, and it's coming. I know that there are a handful of 12-bit 1080p devices on the market now.
Why don't you simply write an article explaining that you don't like that HDMI has a 50 foot limit? That's what it all boils down to after all.
The limitations on effective distance runs are a mess; they were completely avoidable; and that is, indeed, a significant part of my complaint. I am joined in that complaint by many, many people who have had trouble getting HDMI to perform over distance.
You are welcome, of course, not to care that the HDMI standard is so fragile that it doesn't work reliably at distances which the designers could easily foresee users would ask it to work at. But the frustrated users do care, whether you do or not. It is not unreasonable for people to care. What I find puzzling is that it seems to make you very angry that other people do care about this issue.
Now, apart from writing articles, I am actually DOING something about it. As our Belden HDMI update article describes, we actually have, by using Belden's patented bonded-pair technology, managed to make an HDMI cable which, in our in-house use tests, has been capable of carrying 720p and 1080i video flawlessly for a distance of 150 feet on a purely passive cable. This cable was designed principally by David DeSmidt, referenced above (one of those engineers, as you'll recall, who has stated outright to me that HDMI should have been run unbalanced, on coax), and in the meantime we are resolving manufacturing issues in an effort to make the cable economical to terminate in the U.S. rather than China. Nobody here is merely griping and whining; we are solving the problem, and trying to deliver a product to the consumer at the lowest practical cost. But the problem did not need to exist in the first place.
