Review (April 2007)
By Kevin Nakano
With the growth of high-definition TV comes the need for interconnects capable of handling the massive amount of digital data between components. The cable of choice for this task, largely driven by the consumer electronics industry, is HDMI. Addressing the needs of both the content providers and the consumer, HDMI cables have become the new digital link that provides the vital data between source and display components. Unlike many of the older digital cables used solely for audio, HDMI cables carry both high bandwidth video and audio. HDMI was born out of the older DVI specification used for computer PC video. The latest HDMI 1.3 specification calls for significantly higher bandwidth requirements (10.2Gb/s total or 340MHz per channel) than the earlier versions due to an increase in resolution, color depth, and frame rates. As resolutions increase from 720p and 1080i to 1080p, so does the need for signal bandwidth. In addition, the HDMI specification also supports Deep Color, which allows the source to double the number of bits allocated for each color component. Additional features include support of higher frame rates (120Hz), although no one that I know has yet made use of this feature. There is also new audio support for Dolby's TrueHD and DTS-HD Master Audio standards, which offers up to eight discrete channels with superior audio quality when used with compatible audio decoders.
With all these wonderful improvements in consumer video, come the significantly higher data rate requirements. Unfortunately, many HDMI cables that might have worked fine in the past (at 720p or 1080i rates), fail to meet the performance requirements for the HDMI 1.3 standard. There are many HDMI cables available from a variety of manufacturers, yet a large number of them do not perform at the higher data rates, resulting is visible picture artifacts. To make matters worse, ceiling mounted projectors typically require long cable runs, making it difficult for installers to find a solution. The concern is real and we have seen the results in our home theater system. Several of the HDMI cables that we have used at 1080i rates, fail to perform consistently when pushed to 1080p, resulting in speckles or even loss of synchronization in some cases.
To address this problem, a company called VizionWare has launched a new breed of high performance HDMI cables for the A/V industry. Originally founded by Ken Egan (the company's current Chief Technology Officer), VizionWare has developed it's core digital technology in silicon and that has found its way into their new HDMI product line. Unlike passive HDMI cables that rely on fancy gold-plated contacts and exotic wire, VizionWare's Hi Wirez cable design takes a system level approach to the problem to increase performance. The company solves a variety of issues that plague current HDMI cable designs by leveraging from some very innovative technologies core to the company's array of patents, many of which are pending.
Conventional passive HDMI cables suffer from poor signal amplitude and phase dispersion throughout the cable, especially as the cable length increases. The result is signal attenuation which prevents the reliable transfer of data, and which ultimately affects picture quality. Active electronics in the Hi Wirez cable plays a key role in the performance margin gained by their design. HDMI/DVI signals are specified as CML (Current Mode Logic) signaling that only sinks current to one half of the true and complement differential pair at any given time. This asymmetric drive causes common mode radiation and load differences in the cable. The Hi Wirez cable design regenerates the source CML signals into a modified LVDS (Low Voltage Differential Signaling), a truly symmetrical and balanced drive. VizionWare's signal balancing and equalization techniques allow the data to be sent over longer runs with excellent data recovery at the other end of the cable. Once the data is recovered at the destination end of the cable, the data is then converted back into CML signaling for full HDMI signal compatibility. The Hi Wirez cable also implements advanced coding techniques they call Optimal Spectral Diffusion to reduce the spectral energy induced by horizontal and vertical (HSYNC & VSYNC) synchronizing coding symbols. This Transition Density Management improves the BER (Bit Error Rate) and reduces the probability of EMI. The result is an HDMI cable design that works well over long lengths with plenty of noise margin. The Hi Wirez HDMI cable fully supports 1080p, 1080i, 720p, 540p, 480p, and 480i resolutions and is available in 1m, 2m, 5m, 7m, 10m, 15m, and 20m lengths.
VizionWare provides an AC power adapter with the Hi Wirez HDMI cable that is designed to input power from either end of the cable, depending upon where power is most easily available. The linear power adapter (lower noise) provides 6VDC at 700mA with the center pin positive. We connected the AC adapter on the transmitting end of the cable as it was more convenient for us to get power there.
We started viewing some Blu-ray DVDs from our sample collection. Black Hawk Down and Talladega Nights were the first movies to be watched. We have only been watching 1080p for a couple of months now and it is a significant improvement over 720p. Picture quality is spectacular in full 1920 x 1080 resolution with no visible artifacts contributed by the Hi Wirez cable. That is not to say there are no artifacts in these pictures, just not anything we can say came from the cable itself. In comparison, some of our earlier HDMI cables most certainly exhibited problems when pushed into the 1080p arena. One of our longer cables produced speckles around high contrast areas while another exhibited intermittent loss of video synchronization during playback. As with many movie transfers, there are usually some subtle, yet visible artifacts that are the result of the telecine (film-to-video) process, which are usually due to compression and/or low level noise or grain in the picture. This is something we have noticed even in the early transfers of the D-Theater D-VHS tapes. The trick is to identify issues related to the cable itself. In our test, we found absolutely no problems with the Hi Wirez HDMI cable.
What really impressed us with this cable was the new PlayStation3 games, such as NBA 07 featuring full 1080p at 60 frames per second. The PS3 has incredible processing power and these games unleash vivid colors and with extremely high resolution and fast action. While I haven't been a gamer for quite a long time, it is apparent that our kids are now spoiled with the new products. We can see why HDMI 1.3 has such wonderful potential with source material that is only going to get better with time. For driving enthusiasts, there is an F-1 car racing game that makes you feel like you are really behind the wheel of a Formula-One race car. Even though the resolution of this game is limited to 720p, the realism is impressive enough to cause some motion sickness from those watching the race from the driver's seat on the 100" Stewart filmscreen.
- Kevin Nakano
Mitsubishi HC5000 Full 1080p High-Definition LCD Projector
|Review at a Glance|
VizionWare - Hi-Wirez Digital Interconnects
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