Recently I've been reading "Videodisc and Optical Memory Systems
by Jordan Isailovic" and it discusses the analog FM bandwidth of the 12-inch optical LaserDisc - which is around 13.1 MHz using a HeNe laser. So it got me wondering, if analog FM Pulse-Width-Modulation coding were applied to an HD-DVD or Blu-ray disc, what would the disc allow in FM bandwidth?

AFAIK, I think the analogy doesn't apply: Laserdisc was an analog signal (thus the FM bandwidth), whereas HD DVD and BD (like CD and DVD) are digital signals. You'd have to completely re-design the lasers, circuitry, and disk media to incorporate what was done using laserdiscs.

That's how I understand it. I'm willing to be corrected, though.

shinksma

I realise they are totally different, BUT, all of them are binary coding - i.e. pits/bumps. IF the digital signals were replaced with FM, I just wonder what the resulting full bandwidth capability would be - all that would be changed is the encoders/decoders to create a FM PWM signal to feed the laser modulator. Of couse, there is no reason to do that - I'm just wondering what HD-DVD/Blu-ray's bandwidths are if you were to store FM signals.