The main focus of DPL Labs is to provide a mechanism for dealers and consumers to determine which cables have a true ability to carry high-bandwidth, high-definition HDMI signaling with the highest degree of accuracy. DPL engineers have known for years that if HDMI solutions were not capable of providing a performance level with enough signal integrity, it would be just a matter of time before consumers would begin to see limitations, or performance issues, from the products they own…or those they upgrade to in the future. The bottom line is, if you don’t have solid signal integrity performance, the system will most likely fail at some point in time.
Yet system failure is very preventable provided that the equipment that makes up the system has the necessary level of integrity to carry HDMI’s complex and wide-bandwidth signal data. And like any consumer product that must work in conjunction with other products within its space, a set specification must be enforced to provide harmony amongst manufactures and suppliers so the end-user can easily purchase and use the product as intended.
As many of us have learned over the past few years, things did not go that smoothly with the deployment of the HDMI specification. To say that there was “harmony” amongst the wide assortment of HDMI products is like saying that water can be used just as easily as gasoline to power our motor vehicles.
This lack of harmony became quite obvious as we began to test different products for DPL approval. There were many times when an HDMI cable came in claiming it was capable of supporting every feature HDMI has to offer – but went on to fall short when pushed under the extreme testing necessary to verify its claims. These cables would perform reasonably well under normal operating conditions; however, once pushed to deliver higher-end features, performance anomalies began to show such as sparkles, intermittent display functions, or even a dead display.
Figure 1 is an illustration that shows the impact of a high bandwidth requirement on HDMI’s feature delivery capability. As the required bandwidth increases, there is an inherent attenuation (or reduction) of the signal level.
This relationship between the demands of an increased bandwidth and HDMI’s ability to deliver higher-end features is the reason why the industry tends to struggle as HDMI revises their specification to incorporate or expand into new technology arenas. Under HDMI Rev. 1.2, the specified bandwidth had only risen to a relatively easy-to-address 500 MHz. However, over the past few years under HDMI 1.3, this bandwidth increased…by double…making it that much harder to provide support for all the features and benefits HD television has to offer.
For the most part, it has been a cake walk supporting the 720p resolution that a cable box or satellite receiver would output. Even when stepping up to a Blu-ray player where the resolution increases to 1080p – this still only requires half the specified bandwidth now required for HDMI products to support.
But 3D technology, now being installed in more and more consumers’ A/V home entertainment systems, places greater demands with even higher bandwidth requirements at the top of the scale. Just look at Fig 1 and you can see that 3D technology is on the right hand (higher) side of the bandwidth chart.
DPL’s tech support lines are experiencing a noticeable – even alarming – increase in the number of calls on issues related to 3D system installations…even with the lower level Side-by-Side 3D technology. And even more tech calls are being generated on systems featuring the higher-bandwidth Sequential Framing technology. Talk about a lack of harmony!
Even consumers purchasing very expensive 3D products and operating them over relatively short-distance HDMI installations are having problems. But don’t be surprised by this! When you take into consideration the natural tendency for high frequency signals to attenuate over cable distances at a rate of approximately 1 db per meter with standard 24 gauge cable – a run of 7 or 10 meters could easily result in a signal drop of as much as 10 db before you even hit the 3D TV input. And that dramatic signal loss is when all other factors are perfect and all the planets are aligned.
So what does all this mean? It means that as the leading edge continues propel forward into new, more spectacular future technologies, the industry will demand more and more from high-speed, high bandwidth digital signaling solutions like HDMI. It behooves all industry players to grasp the need to include a degree of over-engineering such that the interconnected A/V systems of the future have enough signal integrity headroom to ensure trouble-free operations for consumers.
Whether you manufacture source products, cables, or displays…or if you are the system integrator charged with installing and integrating these products…we all need to pay close attention to the need to properly, and carefully, transport that high-speed, high bandwidth, high-definition digital signal. It is the only way to prevent the client and customer from seeing RED…in 3D.