Thread: video sync rates

Standard TV rates are far lower in resolution than computer rates. NTSC runs 15.75kHz at 60Hz, and is interlaced. Most compuiter video cards I know of won't do this, only specialized cards that have conventional video outs.
If you are set on using your onboard video, I would use the scan converter cable, but remember to enlarge all your fonts, and the image will look fuzzy as compared to a conventional computer monitor.

thanks ... i knew that. ;-)) but the lcd i have will take direct rgb input all i had to do is combine h sync and v sync and feed in to composite sync on lcd.. but they need to be set to 15,625 Hz and 60 Hz. does any one know the h sync frequency of vga at 640 480 resolution??? maybe i can do a divide by two on the hsync from straight vga??

H synch Frequency for 640x480 at 60Hz is 31.5kHz. What kind of monitor is it? You may also need to set your video card to an interlaced output. For more info about scan rates and computer standards, check out www.vesa.org www.extron.com www.avavenue.com

thanks mate.... i found that out myself....
its a 4" sharp.. will take either ntsc or rgb in... ntsc would have to be interlaced but i dont think the rgb would... and as for the sync rate i will try a divide by 2 on the h sync before combining with the v sync..... should work in theory... i dont think the delay throug div 2 would be a problem at such low freq... ie 15 KHz. thanks for the sites will checkthem out anyway

I would guess that it is only an NTSC monitor, so the RGB input signal will probably need to be interlaced as well. (An NTSC signal can be carried in RGB format)