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Conference napalm::commusic_v1

Title:* * Computer Music, MIDI, and Related Topics * *
Notice:Conference has been write-locked. Use new version.
Moderator:DYPSS1::SCHAFER
Created:Thu Feb 20 1986
Last Modified:Mon Aug 29 1994
Last Successful Update:Fri Jun 06 1997
Number of topics:2852
Total number of notes:33157

46.0. "PCM definition" by BARNUM::JWALTON () Tue Dec 11 1984 16:45

	Does anyone out there know how pulse code modulation
	works.
	I'm looking for an alternative to 16 bit A/D
	conversion. I know that some new products use it,
	but I can't seem to figure this process out by
	myself.

	johnb
	oops...no b.
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46.1KATADN::BOTTOMWed Dec 12 1984 07:297
This may seem dumb but PCM is defined as: 
    Modulation of a pulse train in accordance with a code.

I think that there must be something more around here somewhere, I'll get back
to this note if I find anything.
					*db* just another maineiac

46.2KATADN::BOTTOMWed Dec 12 1984 08:226
I knew I could find more. I have an extract from an engineering guide. I will
send it to anybody who is interested. Please contact me at KATADN::BOTTOM
send your loc/mailstop and I'll send a copy. It should answer all of your 
questions.
				*db*
*relax have a homebrew*
46.3PIPA::JANZENMon Dec 17 1984 08:165
Pulse code modulaton doesn't mean anytingg in particular, but they probably
mean pulse width modulation. Pulses are sent out at some rate, and the width
of each pulse indiccates the value being represented.
That's the way I would do it if I were putting music on video.
Tom
46.4KATADN::BOTTOMThu Dec 20 1984 09:396
There is a book in the TWO (Tueksbury) Library that covers PCM in great detail.
It is: PCM and Digital Transmission Systems. The author is Frank Owen. I now
have this book, but will be returning it before the end of this year. It seems 
to be more devoted to analog to digital conversion than the other way but the 
basic techniques should hold up in both directions.
				*db* merry christmas
46.5BARNUM::JWALTONFri Dec 28 1984 09:2618
	Thanks for the excerpts form the book. It seems that 
	PCM is what I had thought it was, that is, the method
	used in most A/D aplications is pulse amplitude modulation.
	I've been familier with this stuff for a while, but was
	misslead by the advertising industry!! Imagine:

	-> PCM technique far superior to traditional analog
	   to digital conversions!! <-

	So I thought "Well something new, wonder what is is?"
	Obviously there isn't.

	But the book did help me with some calculations pertaining
	to sample rate/bandwidth, seems safe to be above 60KHz for
	full 20 to 20. 


	'blind' John