[comp.periphs] How Do Modems Work?

Dave_Ninjajr_Flory@cup.portal.com (08/08/89)

I would really like to what carrier frequency the standard 1200, 2400, and
9600 baud modems us. Also what phase amplitude changes they use and thier
bit number, etc. and what ever anyone knows about TCM. Trellis Code modulation
error checking. (How does it work.)

Thanks for your time.






Anything else I should know?

die@cpoint.UUCP (David I. Emery) (08/11/89)

In article <21117@cup.portal.com> Dave_Ninjajr_Flory@cup.portal.com writes:
>I would really like to what carrier frequency the standard 1200, 2400, and
>9600 baud modems us. Also what phase amplitude changes they use and thier
>bit number, etc. and what ever anyone knows about TCM. Trellis Code modulation
>error checking. (How does it work.)

	The best reference for this that I know of is the CCITT standards
documents (the so called Red Books).  These contain precise and specific
definitions of the standards for all the internationally standardized modem
modulations.  Proprietary modem formats (such as Trailblazer PEP) are
hard to find documentation for, reverse engineering is usually needed
to figure it out.

	The Red books are available through a couple of US companies
but are not cheap.  If you have access to a serious technical library
you might be able to find copies there.




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	David I. Emery   Clearpoint Research Corp. 
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