The advent of High Definition TV or HDTV compelled manufacturers to come out with more and more digital devices. We have witnessed the proliferation of HD equipment such as HD DVD players, Blu-ray players, game consoles, HD-equipped computers, and HDTV display. With all these new high-definition sources and display devices, how do we connect the desired input to the desired output device? There are several ways to do this – by using a HDMI switch, a HDMI splitter or a HDMI matrix.
A HDMI switch allows the user to select multiple sources, such as Blu-ray players and game consoles into one HDTV monitor. Models available may start with a 4 x 1 configuration, which means that there are 4 inputs and 1 output. There are also 8 x 1 or even 16 x 1 switches available. On the other hand, a HDMI splitter is needed when there is a single HD source, which needs to be connected to two or more HDTV displays. Splitter/ switch combinations (HDMI matrix) are also available that will let you select which source is routed to which display.
A passive HDMI splitter can be a simple Y-cable that takes a single high definition input and connects it to two output displays. This will let you watch the source signal on any one display, with the other display powered off. An active HDMI splitter allows the simultaneous display of audio and video signals from a single source in multiple high definition displays. The splitter utilizes a single cable to connect the HD source to the splitter and then individual cables to each HDTV display. A larger distribution configuration, comprising of a greater number of displays is possible by chaining multiple splitters. These splitters may also have the ability to amplify and boost the signals, allowing the use of longer cable runs from the splitter to the display devices.
It should be worthwhile to note that there are a number of design considerations in the manufacture of HDMI switches or splitters. The first is impedance match. Any mismatch introduced by the switch or splitter will cause “reflections” that will degrade the transmission of the HD signal from the source to the monitor. The next is insertion loss that may result from the insertion of the switch or splitter between the HD devices. Any signal loss will also result to the degradation of the transmitted signal. The last but not the least is cross talk. With multiple inputs or multiple outputs being active at the same time, there is a great chance that they will interfere with each other. This should be kept as minimum as possible to avoid degradation of any of the active signals.