Eye Patterns Validate 1080p HDMI Switcher

This article is weak. It doesn’t explain how to read an eye pattern, what the different aspects of the waveform mean, or what problems would be visible or audible during playback if you compromised one or another aspect of the cable or switch.

I disasgree Jason. Indeed, it doesn’t explain much about the eye pattern, but that isn’t the point of the brief commentary. It is targeted at those who already are familiar with the eye pattern, and addressing the misconception that it isn’t an important evaluation tool.

I don’t think most dealers really care how to read an eye pattern—it’s normally done at the mfr level. They just care whether or not it is a valid measurement for qualifying HDMI products.

IF people are interested in more in-depth info on what the eye pattern is and how to read it, please let us know, and we can get something written to that effect.

Thanks

Yeah, but saying that a product passed the eye pattern test is like saying George Bush passed his public speaking course in college. I’m sure he did, but the end result is still pretty ugly.

There are tolerances within which a product can pass the eye pattern. Some products, such as Mr. Boccaccio’s claim of the aforementioned switcher, pass with flying colors. Others make it by a whisker. The problem is that when you have a source, two cables, a switcher and a display in the line, if more than one of those items is relying on that whisker, chances are that you’re gonna come up a bit short.

My point is that since we occasionally see manufacturers displaying their products’ eye pattern on a scope on the show floor and it would be nice to be able to tell who’s got the goods and who’s hoping we don’t know what we’re looking at.

I would like to know how and by whom will cable testing be administered. Will there only a single testing facility or will it be more distributed with easily obtainable hardware/software. Will there be heafty InVisions liscensing fees that will add cost to already expensive cables and prevent moderate or even cheap cables from being tested? In order for this to work, I would hope testing would be easily accomplished and universally accepted so that the end user be it consumer or installer may know what each and every HDMI cable’s rating is regardless of origin and cost.

There is a limit as to how much data can be posted in columns like this due to limited space. The column is regulated with a 300 word limit. Many of these articles are chopped up in order for me to make the 300 word limit requirement.

As far as the eye pattern is concern. Many fail to realize that the eye is only part of the measurement. The meat of the this data comes from the margin the eye has over the mask. The mask, the image inside the eye, can vary in size depending on the spec. HDMI has their own spec for this. The key is to see how much margin over and above the spec is achieved. The Dynamic Headroom of the eye explains just part of the story. There is much more dealing with timing,  load impedance, intra and inter pair skew, DDC serial integrity, and supply current. All of these variables have to be analyzed to offer a meaningful quality level. This level of testing requires hundreds of thousands of dollars in test equipment to measure these devices.

An article on how to read eye patterns would be useful. More importantly pointing on how to fault find from eye patterns.

Jeff is the man. I have taken his course and as a 30 year vet I can tell the difference between a book reader and real technician. He knows his stuff.