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Video and data projection
What you should know about scan rates

Why do many projector and monitor manufacturers specify scan rate ranges as well as resolution? Donít they mean the same thing?

The scan rate ranges offer a more exact way of specifying whether your projector or monitor will match up with a particular PC or workstation.

The reason is that a computer outputting a particular standard (SVGA for example) can be anywhere within a range of scan rates, and the scan rates will vary from brand to brand. Yet your projector must be able to lock on to the particular scan rate your system is outputting. Sometimes that can be a problem if your computer is at the high end of the range; it can also be problematic if youíre using an engineering workstation with a non-standard output.

The most commonly used scan rates
Resolution Horizontal
frequency range
frequency range
CGA 15.575 Khz 60 Hz
VGA (640 x 480) 31.5 - 43 Khz 60 - 85 Hz
SVGA (800 x 600) 32 - 54 Khz 50 - 85 Hz
XGA (1024 x 768) 48 - 80 Khz 60 - 100 Hz
SXGA (1260 x 1024) 52 - 80 Khz 50 - 75 Hz


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