Video Bandwidth
While HDMI and DVI switches have been manufactured, VGA is still the most common video connector found with KVM switches, although many switches are now compatible with DVI connectors. Analog switches can be built with varying capacities for video bandwidth, affecting the unit's overall cost and quality. A typical consumer-grade switch provides up to 200 MHz bandwidth, allowing for high-definition resolutions at 60 Hz.
For analog video, resolution and refresh rate are the primary factors in determining the amount of bandwidth needed for the signal. The method of converting these factors into bandwidth requirements is a point of ambiguity, in part because it is dependent on the analog nature and state of the hardware. The same piece of equipment may require more bandwidth as it ages due to increased degradation of the source signal. Most conversion formulas attempt to approximate the amount of bandwidth needed, including a margin of safety. As a rule of thumb, switch circuitry should provide up to three times the bandwidth required by the original signal specification, as this allows most instances of signal loss to be contained outside the range of the signal that is pertinent to picture quality.
As CRT-based displays are dependent on refresh rate to prevent flickering, they generally require more bandwidth than comparable flat panel displays.
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