Cecil Moore wrote:

hnmm wrote:
Human eyes can detect the refresh rate flicker up to a certain
frequency. My peripheral vision can detect the 120 Hz flicker
of florescent lights as well as flicker in computer monitors.
Drives me crazy.

The scan rate of most computer monitors is closely related to multiples
of the scan rate of a NTSC television signal scan rate. This leads to a
signal that is often twice the rate of NTSC scan. But since the monitors
are not synchronized, the computer monitor will show lighter and darker
areas depending on it's scan rate. Computer monitors will vary in their
"look" on television, from a whole screen flicker to a darker colored
bar that works it's way down the screen. This is all due to the scan
rate frequencies.

- Mike KB3EIA -

On Sat, 03 Jan 2004 20:09:14 GMT, Mike Coslo
wrote:

Cecil Moore wrote:

hnmm wrote:
Human eyes can detect the refresh rate flicker up to a certain
frequency. My peripheral vision can detect the 120 Hz flicker
of florescent lights as well as flicker in computer monitors.
Drives me crazy.

The scan rate of most computer monitors is closely related to multiples
of the scan rate of a NTSC television signal scan rate. This leads to a
signal that is often twice the rate of NTSC scan. But since the monitors
are not synchronized, the computer monitor will show lighter and darker
areas depending on it's scan rate. Computer monitors will vary in their
"look" on television, from a whole screen flicker to a darker colored
bar that works it's way down the screen. This is all due to the scan
rate frequencies.

Yes, the exception would be if the monitors and the TV camera are
synchronized, as might be done with the news set.

Happy trails,
Gary (net.yogi.bear)
------------------------------------------------
at the 51st percentile of ursine intelligence

Gary D. Schwartz, Needham, MA, USA
Please reply to: garyDOTschwartzATpoboxDOTcom

"Mike Coslo" wrote in message
t...
Cecil Moore wrote:

The scan rate of most computer monitors is closely related to multiples
of the scan rate of a NTSC television signal scan rate.

How do you work that out? NTSC is 60Hz (30Hz Interlaced)
So Most CRT monitors run at 70Hz, 75Hz, 85Hz and maybe 100Hz for a high end
monitor at 1024*768

Where is the link between the vertical refresh rates?

Have a google search for Vesa refresh rates for more info.

Robin.. ( I used to work for NEC building computer monitors before NEC
pulled out of manufacturing them in the UK)

Robin,

I *haven't* worked in this area, but I still knew this comment was misplaced
since I've seen all kinds of scan freqs over the years.

--
Steve N, K,9;d, c. i My email has no u's.

"Robin" wrote in message
...
"Mike Coslo" wrote in message
t...
Cecil Moore wrote:

The scan rate of most computer monitors is closely related to multiples
of the scan rate of a NTSC television signal scan rate.

How do you work that out? NTSC is 60Hz (30Hz Interlaced)
So Most CRT monitors run at 70Hz, 75Hz, 85Hz and maybe 100Hz for a high
end
monitor at 1024*768

Where is the link between the vertical refresh rates?

Have a google search for Vesa refresh rates for more info.

Robin.. ( I used to work for NEC building computer monitors before NEC
pulled out of manufacturing them in the UK)