TANK1
Enthusiast
Nov 30, 2006, 12:10 AM
Post #4 of 11
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Re: [chipper] Only one HD port on my HDTV !help!
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Some information on a HDMI switch What features do I look for in a HDMI switch: - Expandability: 4 ports devices are recommended for future expandability. If you use a 2 port, then you have no expandability. It is likely that future HD sources such as games stations, HD DVD player/recorders will utilize HDMI. - HDCP transparancy: any switch must pass HDCP data between source and monitor. - Backward compatibility with DVI-D: There is a mix of both HDMI and DVI-D devices in the field. Users should select a HDMI switch rather than a DVI-D switch since HDMI is backward compatible with DVI-D. With a HDMI switch., the user just chooses the correct cables needed; either HDMI or HDMI to DVI-D to customize to your system. - Remote control: A remote control to select the desired channel is essential. Design consideration of a HDMI switch: HDMI is extremely high speed digital transmission standard with an aggregate data rate of ~4.95 Gbps. Jean Baptiste Fourier (1768-1830) showed that any signal waveform can be resolved into a summation of harmonically related sine waves. The amplitude of the sine waves can be determined by calculation of Fourier transforms. So what in the world does some dead French mathematician have to do with the HDMI switch? Well, Fourier tells us that the waveform is a summation of harmonically related sine waves. Therefore, higher data rate, higher frequency sine waves. Incidentally, the frequency of the fundamental sine wave is ˝ of the data rate. For example, the fundamental frequency of a 2 Gbps ( 50 %duty cycle ) square wave is 1GHz. As data rates increase, every aspect of the switch design (every millimeter) becomes critical because the wavelengths of the signals approach the size of the components on board. The 3 critical parameters to consider are: Impedance Match: HDMI is based on a 100 ohm (differential) impedance. It is imperative that the switch be optimized to match this characteristic impedance. Any imperfections of the board layout will cause “reflections” which degrades signal transmission to the HD monitor. Think of “reflections” as signals that are lost between the inputs to the output. Utilizing careful RF and Microwave layout techniques minimizes these reflections. Minimum Insertion Loss: Signal loss should be minimized in order to maximize signal integrity to the output of the HDMI switch. Again, utilizing careful RF and Microwave layout techniques minimizes insertion loss. Minimum Cross Talk: With multiple inputs (up to 4), all potentially being active at same time, it is imperative that the desired channel not be interfered from any undesired channels. Again, careful RF microwave design techniques minimize cross talk. Since you are using it for gaming , will the Radio Shack model have any lag ? If so you can always return it. Will it accept HDCP signals ? What is HDCP? HDCP stands for High-Bandwidth Digital Content Protection, a copy protection scheme to eliminate the possibility of intercepting digital data midstream between the source to the display. The format designed by Intel and licensed by Digital Content Protection, LLC using an authentication and key exchange procedure before video and audio is presented. Products compatible with the HDCP scheme such as DVD players, satellite and cable HDTV set-top-boxes, as well as few entertainment PCs requires a secure connection to a compliant display, the process often described as the handshake. Due to the increase in manufacturers employing HDCP in their equipment, it is highly recommended that any HDTV you purchase is compatible. Although most video devices support high-definition video over component output, analog connections are scheduled to phase out in the future or possibly forced to limited resolutions output. Why is it important to me? Although manufacturers are still making most products with at least component HD output, new generation of products like HD-DVD and Blu-Ray devices will limit the analog output resolution (Analog defined as Component or RGBHV). The highest resolutions these devices can output (720p/1080i/1080p) will be available on via the digital (DVI or HDMI) connections that employ HDCP encryption. Any new HDTV purchase should have a digital HDCP compatible input. Hope this information helps
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