bryant@oakhill.UUCP (Bryant Wilder) (07/21/86)
posted july 20, 1986
many weeks ago i saw a lot of discussion about v.32 modems that
were either announced or were already being used by some of the
people on net.dcom. the discussion pretty much went away when
it was suggested that the modem companies have not yet put the
technology in the boxes to do a real ccitt recommendation v.32
modem. a few weeks ago i saw a product announcement in ieee micro
from concord data systems for a "full duplex, 9600/4800 bps v.32 modem."
can anyone tell me whether the concord v.32 is a real v.32? if
the answer is yes, what kind of digital signal processing tech-
nology does the modem use? does it use home brew dsp technology
or does it use chips from ti or nec? what type of a/d and d/a
technology do these modems use? is there a real v.32 modem on
the world market? who makes it (them)?
below is what i mean by a real v.32 modem. i will quote
the introduction from ccitt recommendation v.32.
"this family of modems is intended for use on connections on general
switched telephone networks (GSTNs) and on point-to-point leased
telephone-type circuits. the principal characteristics of the
modems are as follows:
a) duplex mode of operation on GSTN and 2-wire point-to-point
leased circuits.
b) channel separation by echo cancellation techniques.
c) quadrature amplitude modulation for each channel with synchronous
line transmission at 2400 bauds.
d) any combination of the following data signalling rates may be
implemented in the modems:
9600 bit/s synchronous,
4800 bit/s synchronous,
2400 bit/s synchronous (for further study)
e) at 9600 bit/s, two alternative modulation schemes, one using
16 carrier states and one using trellis coding with 32 carrier
states, are provided for in this recommendation. however,
modems providing the 9600 bit/s data signalling rate shall be
capable of interworking using the 16-state alternative.
f) exchange of rate sequences during start-up to establish the
data rate, coding and any other special facilities.
g) asynchronous mode of operation(for further study)."
i think most people who want to use a v.32 modem want to know
whether the v.32 is the 9600 bps variety without disclaimers.
bryant wilder {ihnp4,gatech,seismo,harvard}!ut-sally!oakhill!bryant
motorola microprocessor products group, oak hill, texas