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RE: Hello and Help!

At 05:40 PM 7/20/97 +0000, you wrote:

>(The horizontal resolution is fixed at 252.5 lines.)

Don't you mean 262.5 (half of 525)? But is it not really 525 lines? My
understanding is that just because 262.5 lines are painted as the beam
sweeps downward and the 262.5 alternate lines are painted as the beam sweeps
back toward the top (interlaced scan), the resolution is not cut in half.
The persistence of vision makes it appear as if 525 lines had been painted
in a single frame (1/30 sec). Also, although the resolution is either 262.5
or 525 horizontal lines, isn't the proper term for the resolution in this
direction "vertical resolution"? The number of horizontal lines between the
top and bottom of the screen should be the vertical resolution, shouldn't it?

As I understand it, the horizontal resolution depends on the receiver's
video bandwidth, which determines the number of resolvable points in a
single horizontal scan line. For most receivers, this resolution is in the
neighborhood of 250 to 300 lines. Using a VCR cuts the resolution somewhat.

- -------------------------------
Dan Strassberg (Note: Address is CASE SENSITIVE!)
ALL _LOWER_ CASE!!!--> dan.strassberg@worldnet.att.net
(617) 558-4205; Fax (617) 928-4205