From: jim@n5ial.mythical.com (Jim Graham)
Subject: Re: Courier vs Sportster
Organization: what, ME???  you must be joking.
Lines: 121

NOTE:  followups to comp.dcom.modems (for obvious reasons)

In article <1r0mb9$67h@usenet.INS.CWRU.Edu> da416@cleveland.Freenet.Edu
(Andy Nicola) writes:

>In a previous article, cs3sd3ae@maccs.mcmaster.ca (Holly       KS) says:

>>What is the difference between the US Robotics Courier v32bis external and the
>>Sportster 14400 external? I see that the price of a Sportster has dramatically
>>dropped to below $200 but the price of the Courier remains above $400.
>>
>>Anyone with knowledge of both of these modems or anyone that owns a Courier?

the Courier is their top-of-the-line product, thus the higher price.  I've
never taken a real look at the Sportster line (only Couriers), but from what
I've gathered, it's basically more of an entry-level modem.  probably
doesn't meet the same specifications that the Courier does.  I'm not sure
if the Sportster line is fully DSP driven like the (more recent) Courier
modems are, so upgrades in the future may be an issue.

again, take all of the above with a grain of salt...I've never evaluated
the Sportster, so I'm going by bits and pieces that I've heard.  if you
want a real answer, post the question in comp.dcom.modems and you'll find
people who HAVE worked with the Sportster.

personally, though, if I were going to look at the Courier modems, I'd
buy the Dual Standard...then I'd get both HST and V.32bis.  in fact, this
is exactly what I did.  :-)  I'm sitting here looking at my USR DS right
now.

and now, to correct a few VERY incorrect statements....  folks, if you want
to get reliable answers to modem and/or UART questions, post them to
comp.dcom.modems.  if you post in other groups, you never know what you'll
get in the way of an answer (you may very well get a good answer...or you
may get something like the one below).  at least in cdm, if someone posts
complete and utter bs, you'll see a flurry of folks correcting them (to
avoid spreading faulty info).

>The Sportster at 14.4 has v.42 error control and v.42 bis data compression.

just as it does at lower speeds, too.  there is absolutely nothing in
either CCITT Recommendation V.42 or V.42bis that says that they can only
operate on modems that are running V.32bis.  V.42bis, of course, is
currently only *STANDARDIZED* for operation on top of V.42 (in its primary
mode of operation, LAPM), but that's about as far as that goes.

and just in case there's some confusion on this, V.42/V.42bis are also
supported by the Courier line (unless you have a really ancient one).

>The difference
>with the Courier, is that it can run at 16.8 and only in the HST mode. 

take a second look at the original question:

>In a previous article, cs3sd3ae@maccs.mcmaster.ca (Holly       KS) says:
>>What is the difference between the US Robotics Courier v32bis external
                                                 ^^^^^^^^^^^^^^
see the V.32bis up there?  the question was not about the Courier HST
modem, or about the Courier Dual Standard...it was about the Courier
V.32bis modem.  the modem in question does not support HST, period.  it
therefore does not support the 16.8 kb HST.

also, not all Courier HST / Courier Dual Standard modems support the 16.8 kb
version of HST.  my Dual Standard only supports HST at 14.4 kb.  there are
even older models that only run HST at 9.6 kb.

>This is a proprietary mode of USR and it will only connect to another of
>the same type unit to achieve this speed.

HST is USR's proprietary modulation scheme....  but we're not talking about
HST, we're talking about V.32bis.  V.32bis is most definitely *NOT* a
proprietary modulation scheme.

>The Sportster will do
>asynchronous transmissions as well as synchronous.  The HST is one way
>only.

I do hope you didn't mean for these two sentences to be related in some
way.....

first off, V.32 and V.32bis are both synchronous and asynchronous.  this is
part of the CCITT Recommendation (i.e., part of the standard).  it isn't a
feature unique to the Sportster (I just looked at the appropriate chapter
in the Courier DS manual).

second, HST is not ``one way only.''  more correctly put, it is an
asymmetrical modulation scheme, meaning it doesn't work at the same speed
in both directions.  HST operates at [9.6 / 14.4 / 16.8] in one direction,
and has a low-speed back-channel in the other direction.  the high-speed
channel goes in the direction of the higher data flow.  this is fine if
you're logged on to say, a BBS, and type one letter and get screens of
info back, transfer files (not using bimodem), etc....  there is, of course,
a penalty for turnaround time when the high-speed channel needs to reverse
directions.

V.32 and V.32bis are both symmetrical, meaning they do transfer the full
data rate in both directions at the same time.

third, synchronous vs asynchronous has absolutely nothing to do with
symmetrical vs asymmetrical...they are two completely different topics.

>The HST's will be upgradeable to the v.fast spec when it is available.

again, more correctly put, *SOME* of the Courier line will be upgradeable
to whatever ``V.fast'' is called when it's complete.  if you have the large
footprint Courier modems (like I do), you're S.O.L.....  there was an
upgrade plan a while back to upgrade to a small footprint variety, which
could eventually be upgraded to support V.fast, but the cost of the two
upgrades together pretty much put it higher than just buying a new modem.

later.....
   --jim

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