> > > If the granularity of our control of the signal is 330Mhz, > > > > Ouch, that's a bit of a limitation. I don't suppose the two heads > > could be interlaced together somehow to get 660 Mhz? > > Ok, what we can probably do is use a fixed 330MHz and then, in the > amplifier, delay green by 1/3 and blue by 2/3 of a clock period > relative to red and then just add them together. That gives us > effectively 990MHz. Good enough? Actually, it's not quite that > simple, but since everything is a smooth curve, I think we can fake > it. > > > (Still low, but > > better than 330.) And we lose half of that to Nyquest? > > That loss is elsewhere in the problem, I think. That is, we would get > the same loss whether we used analog or digital to encode the signal.
I was thinking of 330 MHz on the digital side. If it is actually the analog side then never mind about Nyquest. A 990 MHz sine wave should be enough for what I have in mind. I'd also be happy with a 990 MHz spectrum analyzer. Your mileage may vary. > > > can we > > > encode all of the information in the TV signal? Would the steps > > > between digital levels (1024 of them) be too noisy? Could we fix that > > > with a low-pass filter? > > > > Does 1024 levels imply a S/N of 30.103 dB? If so, that would be plenty > > for ATSC, but IIRC a bit low for good quality NTSC. I haven't seen numbers > > for PAL, SECAM, or DVB-T. > > Tying the three channels together effectively triples that. It isn't obvious to me how interleaving red, green, and blue increases the S/N. I googled a bit, and found S/N numbers higher than I recall. :-( Looks like we'd want 56-60 dB S/N. On the other hand, those numbers are likely referring to thermal noise, where this is quantization levels. A bit apples vs oranges? _______________________________________________ Open-graphics mailing list [email protected] http://lists.duskglow.com/mailman/listinfo/open-graphics List service provided by Duskglow Consulting, LLC (www.duskglow.com)
