Are you better off today than you were four years ago with HDMI
long-distance applications? Maybe?
Running HDMI video over long distances has always been a challenge. That has not changed.
What have changed are the new products that, in many ways, have become technological Band-Aids in getting this job done. These products are designed and built in an effort to make these installations easier and more adaptive by way of Cat 5/6 or some coax alternative transmission products. That being said, the scores of folks out there are still having issues with these devices.
So are we just going to have to keep playing a problem-solving “Blame Game” on whom to point the finger, or should it be an “End Game” on how to fix it? DPL Labs still receives calls daily with HDMI long-distance problems.
Case in point, we received a call from an installer that ran a 50-foot Cat 5 system from point A to point B a year ago. Simple enough, but for some reason after a year of trouble-free viewing the video shuts down after 15 minutes. A system reset provided 15 more minutes of viewing. We replaced the ATD (balun) with a new one and gave it whirl … no change. Bypassed the ATD with a short HDMI cable and, as would be expected, the system performed flawlessly.
So do we have a “Blame Game” with a verifiable patch, or an “End Game” with a permanent fix? Up to this point it is a patch. If it were a fix, the system would be re-established to its 50-foot distance and functioning normally. Integrators don’t have the luxury of wasting time and money every time a system burps. There are many reasons why the balun failed, and space does not allow me to go into it in depth. My point is, here we are four years later and still dealing with these types of issues.
As DPL began to start ramping up for baluns testing, it required a certain amount of research in order to understand the true ramifications of what makes one good and one not so good. Two elements had to be examined: the product and the wiring itself. Category 5/6 and coaxial cables were never designed for high-speed HDMI signaling and have inherent characteristics vulnerable to ingress and egress interferences, crosstalk, and inter- and intra-pair skew issues. Product designs have been challenged to overcome timing issues, rise time limits, supply voltages and so on. Initial testing proved that some products did pretty well and some were downright deplorable. None of them were perfect.
Let’s add one more factor to this sea of variables - field termination. It’s no wonder we get these calls. At the end of the day, each installation is susceptible to the integrity of the ATD in combination with the selected cable and termination. I cannot stress enough the importance of keeping these performance levels as far above the bar as possible. It will diminish the risk of problems that may plague each and every installation.
If we supply some logic, deductive reasoning in this case, one can determine some pretty substantial conclusions with each problematic event. This is how each CE pro in the field gains the skill sets necessary to complete each job. No rocket science here - let’s use this 50-foot problem as an example.
If we know that this system fails after 15 minutes using an ATD and yet with a short HDMI cable the problem disappears, that essentially proves the system is functioning properly. The act of replacing the ATD with no improvement confirmed it had to be the cable … but then we replaced it with a new Cat 5 cable, and still no change. The most obvious next step would be to install an HDMI cable with some equalization. In 99 percent of these types of failures, the HDMI cable cured the problem.
Have any of you found any Cat 5/6 or coax cable product that has received an HDMI compliance approval? HDMI cables are transmission lines specifically designed to be immune to these problems by using the correct topology, material and shielded components. The HDMI cable distance limitation is equal to that of coax and Cat 5/6. Today’s HDMI cable electronic solutions are exceptional with controllable gains, clock recovery circuitry and robust bandwidths, not to mention great interference rejection. This is clearly an “End Game” option, should you want to go back to basics.
And if you would like the reason why the aforementioned ATD did fail, write to me and I will explain.