newton2@ucbtopaz.CC.Berkeley.ARPA (10/27/84)
This is prompted by Will Martin's comparison of a pilot-tone
compander system for CD's (interleaved level-control info with audio bits)
to the mechanical "reproducing piano", which encodes the notes to be played
as well as information related to expression (dynamics) on a paper roll.
Seems to me the reproducing piano is a closer analog to a vocoder,
in effect a "transform encoding" scheme that records the data (sampled
measure-for-measure) in the frequency domain as pairs of coefficients
("which note? how loud?").
By the way, although I imagine the notes were/are encoded in a
plainly digital (i.e. discrete) fashion, how 'bout the other stuff?
I seem to remember a musician friend saying something about toothed
wheels or some such quasi-discrete system...
AND STILL FURTHER OFF THE SUBJECT:
(.......but still in the "not much new under the sun" category...)
George Antheil, American composer/tinker whose "Ballet Mechanique"
broke new technological ground in the synchronization of player
pianos (c. 1920s, I think) used the experience he'd gained thereby to
invent what may be the first military spread-spectrum (frequency-hopping, in
this case) secure transmission system, intended for non-jammable guidance of
torpedoes. A pseudo-random sequence of transmitting frequencies was selected
by mechanisms (in torpedo and launching vessel) based on synchronized
player piano rolls! Antheil's coinventor (this is starting to get weird)
was Heddy Lamarr (maybe this belongs in net.trivia.hollywood...).
Regards,
Doug Maisel