dansnsr@nmtsun.nmt.edu (Daniel A. Church) (11/10/88)
I own a USR HST for my Apple //e and was looking through a packet sent to me by USR the other day, and came across a USR HST/IX Modem. The picture shows it just looking like a regular HST. Here's what the facts sheet says: "The 30,000 bps, dial-up data communications solution for UNIX-based computer systems" "Data compression and error control (MNP class 5 and software-based protocols) deliver up to 30,000 bps error-free performance, so the Courier HST/IX quicjly pays for itself in reduced phone charges. And your payback comes sooner than it would with other high-speed modems, because you get this super performance for just $1,295!" "Easy-to-use, menu-based software fully automates standard UUCP (UNIX-to- UNIX Copy Program) utility, and provides powerful additional features in- dependent of UUCP. For example, it monitors file transfers through a 'streaming' protocol that yields faster throughput than UUCP or other block-checking protocols." "Trellis-coded modulation - the most powerful data-signalling technique - lets Courier HST/IX achieve maximum speed over a much wider range of phone line conditions than other high-speed modems." I was just curious if anyone knew there was an HST/IX, or if they were all talking about the plain old HST. I just read a message a few messages back that mentioned the TB+ as being the only low-priced UUCP modem. I guess $1,295 isn't the lowest price for a modem, but it's definitely not too bad, is it? Dan Church
root@sbcs.sunysb.edu (root) (11/12/88)
In article <1414@nmtsun.nmt.edu>, dansnsr@nmtsun.nmt.edu (Daniel A. Church) writes: > "Trellis-coded modulation - the most powerful data-signalling technique - ^^^^^^^^^^^^^^^^^^^^^^^^ Well, my communications textbooks are old enough that they do not seem to cover trellis-coded modulation. Does anyone have a reference to same? Better yet are there any reasonably up to date data comm. theory books which cover contemporary modulation methods? > Dan Church Rick Spanbauer SUNY/Stony Brook
rwa@auvax.uucp (Ross Alexander) (11/13/88)
In article <1414@nmtsun.nmt.edu>, dansnsr@nmtsun.nmt.edu (Daniel A. Church) writes:
] I own a USR HST for my Apple //e and was looking through a packet
] sent to me by USR the other day, [...]
] "The 30,000 bps, dial-up data communications solution for UNIX-based
] computer systems" [...]
] "Data compression and error control (MNP class 5 and software-based
] protocols) deliver up to 30,000 bps error-free performance [...]
^^^^^^^^^^
] HST/IX quicjly pays for itself in reduced phone charges. And your payback
^^^
] comes sooner than it would with other high-speed modems, because you get this
[...]
Oh, really? just don't forget those end-to-end error checks, folks ;-)!
Rossphil@diablo.amd.com (Phil Ngai) (11/15/88)
In article <1813@sbcs.sunysb.edu> root@sbcs.sunysb.edu (root) writes: | Well, my communications textbooks are old enough that they | do not seem to cover trellis-coded modulation. Does anyone | have a reference to same? Better yet are there any reasonably | up to date data comm. theory books which cover contemporary | modulation methods? I can't help you with references but I'm sure you could ask for info from your Codex salescreature or moral equivalent. I could also give you a two paragraph description but it seems you want to get it out of a textbook, which is actually a good idea. -- Phil Ngai, phil@diablo.amd.com {uunet,decwrl,ucbvax}!amdcad!phil
wtm@neoucom.UUCP (Bill Mayhew) (11/17/88)
The HST/IX mentioned sounds like something that some people from USR that I talked to last June referred to as a "TB killer". They claimed taht it would have 2x the thoughput for the same price as a TB modem. They also said that it would have uucp spoofing. It sounds like they may have delivered. By the way, I heard (but can't verify) that some of the people working on the TB killer used to work for Telebit. I'm not sure that I'm ready to change yet. We don't have any machine here that can honestly feed a continuous stream of data into the modem at 30 Kbaud with the uucp g protocol, even with spoofing. We use a separate 3b1 to handle all our traffic that goes out through the TB modems, as the tty drivers of BSD 4.2 are pretty lousy. It was easier to go to the 3b1 for us than to try to rehack the drivers. We're switching over to Ultrix, so it will be interesting to see if we can get better performance for our Vaxen's serial ports. Interestingly, the HST/IX is starting to get pretty close to what Shannon's theorm gives as the ultimate amount of data that can be sent though a dial-up phone circuit. The Shannon-Hartley law states: H = B log_2( 1 + ( P / No B ) ) in bits per second H : channel capacity in bps B : bandwidth of channel in Hz P : received power in watts No : single sided noise power spectral density in watts / Hz This, of course, assumes that the noise received has a gaussian distribution, which may or may not be true in a phone circuit. I guestimated that an average phone cirucit has a usable bandwidth of about 2600 Hz. Tyical S/N ratio for phone lines these days is about 45 dB. Putting that into the above gives me ~38,800 bps. I work in medical electronics as opposed to telephony, so apologies in advance if I've made stupid assumptions here. Reference: _Satelite Communications_. Pratt, Timothy and Charles Bostian, Wiley Books, New York. 1986. p 284. I don't have Shannon's paper, but you might want to look it up: "A Mathematic Theory of Communications", _Bell System Technical Journal_, Part I. 1948. pp 623-656 Another possibility might be that the HST/IX has some nifty data compression sceme, that gives a high thoughput if the data resembles english (or some other language) text. A Trailblazer can give astronomically high throughputs if you feed it 100K of the same character with compression enabled. One must look into what sort of data it is upon which the transfer statistics are based. Please note!! I'm not saying at all that USR is fibbing; just be sure to check it out; Shannon certainly says it is possible. --Bill return mail path: ...!lll-winken!scooter!neoucom!impulse!wtm
root@telebit.UUCP (Super user) (11/18/88)
For the record:
The HST/IX is the identical modem to the standard USR HST.
In the IX form it is shipped with a host based software package known
as Handshake Blazer, built by SST DATA Inc., Milwakee, Wis.
Handshake Blazer operates a protocol that two years ago, I helped Mike Myers,
V.P of Eng. at SST, design. The program was named Handshake Blazer because
it was built for the Telebit TrailBlazer. It is an excellent program and
continues to run very well with the modem it was built for. Functionally it
is like a TERM, MLINK, or BLAST program.
USR OEMs that software from SST DATA and bundles it with an HST and walla!
the HST/IX.
You must order (separate part number) the correct version for your operating
environment. It is available on Fortune, 3B1/2, SCO Xenix, Interactive Unix, &
Unisys 5000/30,50,60,90.
It is not available for Sun, 3B5/15/20, AIX, Pyramid, DEC, HP, Altos, Apple,
etc, etc. UUCP "g" is the only dial-up protocol generally distributed
with all UNIX platforms.
The program provides menu access to Unix's UUCP utility. It in no way
assists the performance of UUCP. UUCP performance, executed via Handshake
Blazer (HST/IX) will be identical to that with UUCP and a standard HST.
For further information I encourage you to test it, talk to USR or contact
the Telebit Corporation at telebit!modems.
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Michael Ballard Voice Phone: (415) 969-3800
Unix Program Manager FAX: (415) 969-8888
Telebit Corporation UUCP: {uunet,ames,sun,hoptoad}!telebit!mikedave@onfcanim.UUCP (Dave Martindale) (11/19/88)
In article <1414@nmtsun.nmt.edu> dansnsr@nmtsun.nmt.edu (Daniel A. Church) writes: > >"Data compression and error control (MNP class 5 and software-based >protocols) deliver up to 30,000 bps error-free performance, so the Courier >HST/IX quicjly pays for itself in reduced phone charges. This is a pretty meaningless figure, since they don't quote the compression ratio. The real measure of how fast the modem is is the throughput on truly random data, where compression does no good. Since most news feeds have already been compressed on the host, and the resulting byte stream is a pretty good approximation to random data, this determines how much you can actually push through the modem. For example, USENET news articles get about a 2:1 compression ratio, formatted text does somewhat better because of all the white space. If USR is quoting their figure based on something that compresses 2:1, then the real modem bandwidth is 1500 cps, only slightly faster than a Trailblazer. But I can get a 4.8:1 compression ratio on uucico LOGFILEs; if USR used something like this as their test case, then the real throughput of the modem is only 625 cps. And if you allow a continuous stream of blanks to be the test case, then any modem with a decent compression algorithm will give you a "throughput" that is limited by its maximum RS232 bit rate. (Like 30 kbps through a 38.4 kbps serial port). For the Trailblazer, the real throughput figure is 1400 8-bit characters per second of useful data, or 14000 bps if you count the start and stop bits. It has good built-in compression, that will allow it to send most data at a speed limited by its maximum 19.2 Kbps serial rate, but that doesn't matter for sending news.