How Blu-ray Affects HDMI Signal Integrity

We recently discussed signal integrity issues in HDMI installations. Let's expand on that.

In the early days of HDMI (Version 1.0), the bandwidth was specified at 1.65Gb/s per channel (or 4.95Gb/s for all three color channels). Life was good. As long as systems were outputting 480p with a 2-channel PCM audio signal, they were performing easily within spec.

But as time and technology progressed forward, so did the demands on HDMI.

Higher resolutions came on the scene - first increasing to 720p, then 1080i and 1080p. As the resolution progressed so did the required bandwidth, making it much more challenging to transport. A system installation designed with enough signal integrity for 480p or 720p would eventually begin to choke on the required bandwidth as the resolution continued to increase.

With the advent of Blu-ray, technology progression is pushing even higher data rates through HDMI - data rates beyond what were ever previously required. Now the industry is experiencing more HDMI system failures. Why?

Simple: it all goes back to the issue of signal integrity. If an HDMI system installation is offering only between 1-10 percent signal headroom margins, simply adding in a Blu-ray player's higher data rate could crush the system's performance and jeopardize its operation.

So how do you troubleshoot system failures? If the system performs satisfactorily with low-resolution products but not with Blu-ray, go back to basics. Run just the Blu-ray connected directly to the display. If that works, start working backward by adding in each component until you lose the video signal.

Be careful, you may find that a product that works fine in a direct configuration may actually be the problem when other components are added. If you see sparkles on the screen, you are on the edge of the cliff as far as signal integrity is concerned.

By substituting components, testing configurations and designing HDMI-based systems with signal integrity in mind you will greatly improve your HDMI installations success ratio - no matter where technology progresses.