david@ms.uky.edu (David Herron -- One of the vertebrae) (06/09/88)
What's this ad here doing laying claim to MNP classes 7 & 8 for? I've
only ever heard of classes up to 6!
The magazine is TPT (Telecommunications Products + Technologies -- a freebie
that I'm getting).It's on page 57 and is from MicroCom. (er.. that's the
original designers of MNP isn't it?). The claims are 12000 bps for Class 7
and 30000 bps in class 8. (QX/12K and QX/30K are the model names). The list
price for the 12K is $799.
Then they have a QX/V.32c which does (surprise, surprise) V.32 and MNP
class 9(!). Claimed throughput on this one is 38400 bps.
The phone number is 1-800-822-8224.
This is interesting. 9600 baud modems are going to become commonplace
and 38400 baud modems are going to be the high-tech new thingy shortly.
But they're all relying on data compression to get these really high
baud rates. And the people who did the BYTE/Data Communications
modem tests found that usually the data compression did not help --
but largely because they were sending random data. I have a feeling
that *any* compression algorithm will fall down on random data --
compression algorithms all rely on finding some large patterns in the
data and replacing each occurrence of the pattern with some short identifier.
I'm also concerned about these modems that are using 2400 baud
technology with data compression & error correction to get higher
speeds. 2400 baud technology is very fragile, it is very easy to get
noise. The error correction will have to work harder in one of these
modems than maybe it should. On the other hand there was that modem in
the BYTE article that even improved its throughput slightly under bad
line conditions. Perhaps these 2400 baud modems would be more likely
to lose connections and be lossy in that way.
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