phil@amdcad.UUCP (Phil Ngai) (04/29/85)
Has anyone seen the new Codex 2660 series trellis coded modems?
I opened one up and am just amazed at what's inside. For example,
the least exotic piece of LSI is a MC68000. I never expected to have
a modem smarter than many computers I have used. The sucker is expensive
($13K) but our calculations show that a 16Kb modem will pay for itself
pretty quickly in many of our applications. Assuming it works.
Down the hall the chip planners are mumbling something about ISDN
making all this analog stuff obsolete. We'll see.
--
I speak for myself and no one else.
Phil Ngai (408) 749-5720
UUCP: {ucbvax,decwrl,ihnp4,allegra}!amdcad!phil
ARPA: amdcad!phil@decwrl.ARPAhes@ecsvax.UUCP (Henry Schaffer) (04/30/85)
First the disk controller chips got smarter (more complex) than the microprocessor CPU, now Phil points out that the modem is smarter than the CPU. Is this just the start of a natural progression towards ....? --henry schaffer
dsi@unccvax.UUCP (Dataspan Inc) (05/01/85)
Pardon my ignorance, but just what is a trellis coded modem? UDS also
supposedly has one which also supports V.29, and is a mere $3900 in onsies;
top speed is said to be 14400 b/s.
This would seem to pay back way faster than the Codex 2660 although
comments on both of them would be appreciated.
David Anthony
Sr. Video Nut.
DataSpan, Inc.phil@amdcad.UUCP (Phil Ngai) (05/03/85)
In article <191@unccvax.UUCP>, dsi@unccvax.UUCP (Dataspan Inc) writes: > > Pardon my ignorance, but just what is a trellis coded modem? UDS also > supposedly has one which also supports V.29, and is a mere $3900 in onsies; > top speed is said to be 14400 b/s. From the Codex literature: Trellis Coded Modulation (TCM): This modulation mode is employed by the Codex 2660 for data rates from 9.6 to 16.8 Kbps over D1 leased lines. The 8-state coded modulation scheme uses twice the required number of signal points (256 points at 16.8, 128 at 14.4, 64 at 12, and 32 points at 9.6 Kbps) to transmit redundant data for superior performance compared to first generation high speed modems. It's a form of ECC for modems, you could say. By the way, you have to logon with a password before you can use the front panel on the 2660. > This would seem to pay back way faster than the Codex 2660 although > comments on both of them would be appreciated. That's possible. A phone line to the Far East is awfully expensive, though. Codex also has a network control system for monitoring line conditions which we seem to like. -- I speak for myself and no one else. Phil Ngai (408) 749-5720 UUCP: {ucbvax,decwrl,ihnp4,allegra}!amdcad!phil ARPA: amdcad!phil@decwrl.ARPA
wunder@wdl1.UUCP (05/07/85)
If 16Kbits is still too slow, how about 19.2K? NEC has announced the 19200M modem for four-wire D1 conditioned leased lines (these are the same kind of line that we run 9600 bit/sec V.29 modems over). Only $12,000, cheap. It has backup speeds of 16.8K, 12K, and 9600, and includes an eight port mux. Me, I'm waiting for the V.32 modems -- 9600 over a dial-up line. wunder
jbn@wdl1.UUCP (05/11/85)
The increasing intelligence of peripherals is certainly reaching
amazing levels. Take a look at any of the intelligent Ethernet controllers.
CMC's is especially impressive; M68000, 128KB RAM, ROM, LANCE chip, etc.
all on one VMEbus card. They had to use 1Mb single inline RAM packages to
make it all fit, but they did it. Excelan's is equally crammed, although
Intel 186 based.
Then there's DEC, which seems to have a corporate policy of not using
microprocessors in peripherals, except maybe a J11 now and then or that
strange mid-70s vintage microengine in the DMC/DMR/KMC board family.
John Naglebrad@kontron.UUCP (Brad Yearwood) (05/14/85)
> If 16Kbits is still too slow, how about 19.2K? NEC has announced > the 19200M modem ... Does anyone know: 1. How to obtain a copy of the V.32 standard mentioned later in the subject article for 9600 bit/sec dialup? 2. Any other good papers (hopefully readable without too much mathemagic) on trellis coding and other techniques used in these incredible-by-212-standards modems? I'm starting with Gottfried Ungerboeck's "Channel Coding with Multilevel/Phase Signals" in IEEE Trans. Info. Theory, IT-28 #1, January 1982. This is rough going for me, so pointers to more directly relevant, diluted, tutorial type articles would be much appreciated. I'm fascinated by the possibility of squeezing a useful bandwidth from my crummy home phone to a computer or network. Brad Yearwood Kontron Electronics (714) 660-0270 {ucbvax!unisoft | scgvaxd | trwrb}!pertec!kontron!brad
greszcz@utcsri.UUCP (John Greszczuk) (05/16/85)
> Does anyone know: > 2. Any other good papers (hopefully readable without too much > mathemagic) on trellis coding and other techniques used in > these incredible-by-212-standards modems? I'm starting with > Gottfried Ungerboeck's "Channel Coding with Multilevel/Phase > Signals" in IEEE Trans. Info. Theory, IT-28 #1, January 1982. > This is rough going for me, so pointers to more directly > relevant, diluted, tutorial type articles would be much > appreciated. ______________________________________________________________________ A good comprehensive tutorial article is : " Efficient Modulation for Bandlimited Channels " in the IEEE Journal on Selected Areas in Communications , September 1984. It is written by Forney, Quershi, Lang and some others who are associated with Motorola Information Systems ( CODEX , ESE ). There are other more specific articles that might be of interest in that special issue on voiceband data communications. John Greszczuk Dept. of Elec. Eng. University of Toronto