What is a Scan Doubler?
This is a special case of a scan converter where the output format has roughly twice the number of lines as the input format and runs at twice the horizontal scan rate. Various scan doubler boxes are available commercially. For example, check out the offerings from Harmonic Reseach. (I have no idea of whether they are any good – just an example.) The following is described for NTSC; A similar approach can be taken with PAL 625/50 to SVGA at 800×600, 50 Hz. To convert NTSC interlaced at 30 frames/second 60 fields per second to VGA which is at 60 complete non-interlaced frames per second requires a simple scan converter. This is basically an NTSC color decoder and video A/D feeding a full frame memory storing RGB (probably at 24 bits), and VGA video D/A. I say simple to compare it to the general case where in addition to frame store, you need a high speed interpolator to convert between resolutions. VGA is close enough to NTSC resolution (at least in terms of the number of active video l
