rfg@hound.UUCP (R.GRANTGES) (05/14/85)
[] Just so as to maintain a balanced view from the corporation, now that one area has spoken like a buggy-whip manufacturer's view of the automobile in 1895, why should we go analog anyplace? AT&T-Bell Labs has released photographs of a direct digital speaker.D/A in the air, so to speak. I think it only handled 4 or 5 bits, but you have to start somewhere. Meanwhile, there are a number of promising ways to drive a speaker with essentially a digital amplifier, going D/A in the loudspeaker. One way I got a patent on about 25 or 30 yrs ago is to use delta modulation (or something like it) with the loudspeaker serving as part of the decoding network for a very heavy pulse amplifier. One can convert from PCM to Delta in logic circuitry, of course. Probably it would not be much more expensive to build a direct PCM to PAM converter with the loudspeaker as the load. You need fast high current switches. -- "It's the thought, if any, that counts!" Dick Grantges hound!rfg
schachte@ittvax.UUCP (Peter Schachte) (05/15/85)
> ... why should we go analog anyplace? > AT&T-Bell Labs has released photographs of a direct digital > speaker.D/A in the air, so to speak. But when do we get digital radio? It might take a tremendous bandwidth to get sufficient error-correction coding, but it would be worth it for hissless sound. And maybe some signal-compression techniques could be used. -- Peter Schachte (decvax!ittvax!schachte)
dmmartindale@watcgl.UUCP (Dave Martindale) (05/18/85)
In article <1666@ittvax.UUCP> schachte@ittvax.UUCP (Peter Schachte) writes: > >But when do we get digital radio? It might take a tremendous >bandwidth to get sufficient error-correction coding, but it would be >worth it for hissless sound. And maybe some signal-compression >techniques could be used. Hey, how about taking over some of the TELEVISION channels? They would allow a bit rate comparable to the CD, wouldn't they? And good-quality audio is certainly a better use of the spectrum than most of what is on TV these days. :-)
rfg@hound.UUCP (R.GRANTGES) (05/18/85)
[] But who needs radio, really. There's those lovely optical fibers... and, if you insist, there are microwaves. -- "It's the thought, if any, that counts!" Dick Grantges hound!rfg