denbeste@bbn.com (Steven Den Beste) (07/06/89)
The term "baud" DOES mean "bits per second", not "characters per second".
We use it just like we use "herz" as a synonym for "cycles per second".
The person who reported that "baud" means "characters per second" is simply
wrong.
As a laboratory demonstration, I have a 2400 baud modem, and I run DNET.
(Great stuff, Matt!) For those of you who do not know, DNET uses the line fully
during downloads - no pauses waiting for acknowledgements. WHen downloading I
get about 10K per minute transfer rate. (And, as the old joke goes, I'm
THANKFUL for it. Just wait'll I have kids and they complain about how slow
their T1 line is.)
10240 bytes per 60 seconds = 171 bytes per second
= 1710 bits per second
The rest is DNET's blocking and protocol and escaping. I'm not getting anything
like 2400 BYTES per second.dhesi@bsu-cs.bsu.edu (Rahul Dhesi) (07/06/89)
In article <42300@bbn.COM> denbeste@BBN.COM (Steven Den Beste) writes: >The term "baud" DOES mean "bits per second", not "characters per second". >We use it just like we use "herz" as a synonym for "cycles per second". The term "baud" refers to the number of signal levels occurring per second. It is equal to "bits per second" only when each signal level carries one bit of information. This is true for serial RS-232 links and for 300-baud modems. But a 2400 bits-per-second modem only uses a 600 baud signalling rate. By the way, your definition of "herz" is wrong too; that's what you write on towels ("hiz" and "herz"). The correct scientific name for "cycles per second" is "hertz", abbreviated "Hz". -- Rahul Dhesi <dhesi@bsu-cs.bsu.edu> UUCP: ...!{iuvax,pur-ee}!bsu-cs!dhesi
cmcmanis%pepper@Sun.COM (Chuck McManis) (07/07/89)
If I may be so bold to put in another "bit" of information :
As most of the followups pointed out so far, baud != Bits/Second.
Instead baud = "signalling transitions" and BPS = data bits crossing
a given interface over time. One of the more subtle points that was
missed was that on regular serial interfaces, something like 9600 baud
is *not* 9600 bits/second. This is due to the fact that the "start bit"
and "stop bit" in the serial stream are often defined as "bauds" but
not as "bits". (You don't see them in the resulting byte of information,
although you can and do reconstruct them to send them back out over
the line). This explains why the maximum throughput of a 9600 baud line
is 960 ASCII characters per second, and yet since characters have 8
bits in them (7 + parity) that yields only 7680 bits/second of actual
data. The entire mess is further cloudied by the fact, as was mentioned
in the followups, that things like 2400 baud modems, may communicate with
the computer at 2400 baud, but talk to each other at 600 baud. So how
could that be? The answer is that a baud is not constrained to a simple
binary value like a bit is. Rather, these modems use quadrature encoding
(or something like that) which gives each baud one of four different
values, allowing each baud to contain two bits.
Fun isn't it?
--Chuck McManis
uucp: {anywhere}!sun!cmcmanis BIX: cmcmanis ARPAnet: cmcmanis@sun.com
These opinions are my own and no one elses, but you knew that didn't you.
"A most excellent barbarian ... Genghis Kahn!"jms@tardis.Tymnet.COM (Joe Smith) (07/07/89)
In article <42300@bbn.COM> denbeste@BBN.COM (Steven Den Beste) writes: >The term "baud" DOES mean "bits per second", not "characters per second". >The person who reported that "baud" means "characters per second" is simply >wrong. True, "baud" does not mean "characters per second". But if you transmit more than one bit at a time, then "baud" does not mean "bits per second" either. One baud is one change of signal per second. A touchtone phone sends 4 bits in parallel when you press one of the 12 keys. If you dial 2 digits per second, then you are running at 2 baud but are transmitting 8 bits per second. A 300 bits per second modem runs at 300 baud, but a 1200 bits per second modem runs at 600 baud at the telephone end because it encodes 2 consecutive digital bits into a single analog signal change. -- Joe Smith (408)922-6220 | SMTP: JMS@F74.TYMNET.COM or jms@tymix.tymnet.com McDonnell Douglas FSCO | UUCP: ...!{ames,pyramid}!oliveb!tymix!tardis!jms PO Box 49019, MS-D21 | PDP-10 support: My car's license plate is "POPJ P," San Jose, CA 95161-9019 | narrator.device: "I didn't say that, my Amiga did!"
bryan@cs.utexas.edu (Bryan Bayerdorffer @ Wit's End) (07/07/89)
In article <114038@sun.Eng.Sun.COM> cmcmanis@sun.UUCP (Chuck McManis) writes: =-If I may be so bold to put in another "bit" of information : =- =-a given interface over time. One of the more subtle points that was =-missed was that on regular serial interfaces, something like 9600 baud =-is *not* 9600 bits/second. This is due to the fact that the "start bit" =-and "stop bit" in the serial stream are often defined as "bauds" but =-not as "bits". (You don't see them in the resulting byte of information, Oh please. Here we had this issue all nice and put to bed, with all the oversimplifiers firmly silenced, and then you go and make it all murky again. Bits is bits, and BPS is BPS. I mean, where would we be if everyone went around dragging the interpretation of the bits into it? I'll tell you--people's bit rates would be dropping by 10% on the same hardware, just because they started sending two stop bits instead of one. And what about bit stuffing? Now the bit rate depends on the data! Pandemonium. You've destroyed the simple, elgant relationship between baudrate and BPS. Now we here in the universities will have to spend untold tax dollars developing a new calculus to explain it to each other, while you industry people drink coffee and hold barbecues. I hope you can live with yourself. ______________________________________________________________________________ /_____/_____/_____/_____/_____/_____/_____/_____/_____/_____/_____/_____/_____/ |_____|_____|_____|_____|_____|_____|_____|_____|_____|_____|_____|_____|_____| _No dark sarcasm in the classroom|_____|_____|_____|_____|_____|_____|_____|___ |____Teachers leave the kids alone__|_____|_____|_____|_bryan@cs.utexas.edu___| ___|_____|_____|_____|_____|_____|_____|{vertebrae...}!cs.utexas.edu!bryan_|___ |_____|_____|_____|_____|_____|_____|_____|_____|_____|_____|_____|_____|_____|
jal@wsu-cs.uucp (Jason Leigh) (07/07/89)
Strictly speaking, data rate is in bits per second. Baud rate is a measure of the modulation rate; i.e. the rate at which the signal level is changed. [Stallings, p.69]
kms@ecsvax.UUCP (Ken Steele) (07/07/89)
In article <114038@sun.Eng.Sun.COM>, cmcmanis%pepper@Sun.COM (Chuck McManis) writes: > If I may be so bold to put in another "bit" of information : > > This explains why the maximum throughput of a 9600 baud line > is 960 ASCII characters per second, and yet since characters have 8 > bits in them (7 + parity) that yields only 7680 bits/second of actual > data. > You mean 9600 baud does NOT equal 960 ASCII chars per second because there are 10 bits per ASCII char in transmission. And 9600 - (2 * 960) = 7680 bits/second of actual data. > Fun isn't it? > Every little bit helps.... > --Chuck McManis --ken -- Ken Steele Dept. of Psychology kms@ecsvax.[bitnet || UUCP] Mars Hill College kms@ecsvax.uncecs.edu Mars Hill, NC 28754
kms@ecsvax.UUCP (Ken Steele) (07/07/89)
Isn't it about time for someone to give us the derivation
of the term "baud." I haven't heard that story in a while
Grandad...
--ken
--
Ken Steele Dept. of Psychology kms@ecsvax.[bitnet || UUCP]
Mars Hill College kms@ecsvax.uncecs.edu
Mars Hill, NC 28754 papa@pollux.usc.edu (Marco Papa) (07/07/89)
In article <7284@ecsvax.UUCP> kms@ecsvax.UUCP (Ken Steele) writes: >Isn't it about time for someone to give us the derivation >of the term "baud." I haven't heard that story in a while >Grandad... From the Glossary of the Black Box catalog (Black Box is a major comm hardware manufacturer/distributor): Baud -- Unit of signalling speed. The speed in baud is or events per second. If each events represents only one bit condition, baud rate equals bps. When each event represents more than one bit (e.g. dibit), baud rate does not equal bps. Baudot -- Data transmission code in which five bits represent one character. Use of letters/figures shift enables 64 alphanumeric characters to be represented. Baudot is used in many teleprinter systems with one start bit and 1.42 stop bits added. [Baudot is the actual last name of the inventor of the Baudot encoding]. BPS (bits per second) -- Unit of transmission rate. Dibit -- a group of two bits. -- end of quote Result: Baud comes from Baudot. -- Marco Papa 'Doc' -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= uucp:...!pollux!papa BIX:papa ARPAnet:pollux!papa@oberon.usc.edu "There's Alpha, Beta, Gamma, Diga and Caligari!" -- Rick Unland -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
UH2@PSUVM.BITNET (Lee Sailer) (07/07/89)
In article <42300@bbn.COM>, denbeste@bbn.com (Steven Den Beste) says: > >The term "baud" DOES mean "bits per second", not "characters per second". Sorry guy. You are wrong. The guy said "symbols per second", not characters (as in ascii). He was refering to the number of detectable signal levels used to encode characters. In the old days, just two signal levels (two symbols) were used, and therefore baud == bps. In many modern modems, different combinations of signal level and signal changes (different sysmbols) can be used to transmit more than 1 bit, and therefore baud < bps. >We use it just like we use "herz" as a synonym for "cycles per second". > >The person who reported that "baud" means "characters per second" is simply >wrong. > >As a laboratory demonstration, I have a 2400 baud modem, and I run DNET. >(Great stuff, Matt!) For those of you who do not know, DNET uses the line fully >during downloads - no pauses waiting for acknowledgements. WHen downloading I >get about 10K per minute transfer rate. (And, as the old joke goes, I'm >THANKFUL for it. Just wait'll I have kids and they complain about how slow >their T1 line is.) > >10240 bytes per 60 seconds = 171 bytes per second > = 1710 bits per second > >The rest is DNET's blocking and protocol and escaping. I'm not getting anything >like 2400 BYTES per second.
doug@xdos.UUCP (Doug Merritt) (07/07/89)
In article <359@mohawk.cs.utexas.edu> bryan@cs.utexas.edu writes: >BPS. Now we here in the universities will have to spend untold tax dollars >developing a new calculus to explain it to each other, while you industry >people drink coffee and hold barbecues. I hope you can live with yourself. ^^^^^^^^^^^^^^ It's a tough job, but somebody's gotta do it! Hey Chuck, throw 'nother shrimp on th' barbie. Bob's gettin' the brews. Doug >_No dark sarcasm in the classroom|_____|_____|_____|_____|_____|_____|_____|___ This adage has no relation to your net humor, I take it. :-) Doug -- Doug Merritt {pyramid,apple}!xdos!doug Member, Crusaders for a Better Tomorrow Professional Wildeyed Visionary
denbeste@bbn.com (Steven Den Beste) (07/08/89)
Part of why I'm confused is that EVERYONE seems to use "baudrate" informally to mean the rate at which the computer can feed bits to the modem. A "9600 baud" modem always is reported to carry 960 10-bit characters per second - even if it is only making 2400 transitions per second on the telephone line.
lee@sed170.HAC.COM (John Lee ) (07/08/89)
In article <42300@bbn.COM> denbeste@BBN.COM (Steven Den Beste) writes: >The term "baud" DOES mean "bits per second", not "characters per second". >We use it just like we use "herz" as a synonym for "cycles per second". Not quite. "baud" means "symbols per second" as Stephan Holmstead reported in his fine article. Note that symbols != characters here. A "symbol" is actually an abstraction that stands for 1 or more bits, i.e., a phase shift of x degrees with an amplitude change to y% in the signal represents a particular sequence of one or more bits. Hence, if a symbol represents only 1 bit, then a 1200 _baud_ modem is indeed a 1200 bits per second modem, but if a symbol represents 8 bits (as a Trailblazer might), then a 1200 _baud_ modem is actually a 9600 bits per second modem. The term "baud" has always been confusing, ever since the term originated when characters (not ASCII, more like paper tape) were only 5 or 6 bits. One could never tell what the character rate was by the baud alone. By the way, Stephan said that it is impossible for a modem to do 9600 baud. What's the theoretical limit? What's the actual baud rate of those MC68000-controlled 30,000+ bps high-speed modems that spread dozens of simultaneous channels across the ordinary voice-line telephone spectrum? >The person who reported that "baud" means "characters per second" is simply >wrong. You're right. >As a laboratory demonstration, I have a 2400 baud modem, and I run DNET. >(Great stuff, Matt!) For those of you who do not know, DNET uses the line fully >during downloads - no pauses waiting for acknowledgements. WHen downloading I >get about 10K per minute transfer rate. (And, as the old joke goes, I'm >THANKFUL for it. Just wait'll I have kids and they complain about how slow >their T1 line is.) > >10240 bytes per 60 seconds = 171 bytes per second > = 1710 bits per second > >The rest is DNET's blocking and protocol and escaping. I'm not getting anything >like 2400 BYTES per second. Gee, are you sure there's nothing else going on? That's only 71.25%. I don't think DNET uses 28.75% of the bandwidth for its protocol. 2400 bps modems are really 240 characters per second. I've timed it out of curiosity when I was doing straight ASCII dumps. ------------------------------------------------------------------------------- Raining CATS and DOGS? Join the RATS: Remote Amiga Teleconferencing System +--------+ John Lee | HUGHES | +--------+ ARPAnet: jhlee@hac2arpa.hac.com Hughes Aircraft Company The above opinions are those of the user and not of those of this machine.
denbeste%bbn.com@mitvma.mit.edu (Steven Den Beste) (07/08/89)
----------------------------Original message---------------------------- >The term "baud" DOES mean "bits per second", not "characters per second". >We use it just like we use "herz" as a synonym for "cycles per second". > >The person who reported that "baud" means "characters per second" is simply >wrong. This is probably nit-picking BUT Baud does NOT mean bits per second. Baud (after J.M.E. Baudot) refers to the number of, for a lack of a better term, packets per second. >As a laboratory demonstration, I have a 2400 baud modem, and I run DNET. You have a 600 baud modem running 4 bits per baud (packet). 1200 "baud" modems are 600 baud at 2 bits per baud. 300 baud is indeed 300 baud. Your calculations are somewhat correct because a "2400 baud" modem is running at 2400 bits per second. Remeber, however, the number of bits per character CAN vary. (People actually impressed with that useless bit of information can recieve an authenticaly signed copy of the posting by sending two dollors to "transcrips" P.O. Box .... |-) /* F. Michael Theilig OHA101 at URIACC.Bitnet "There is no Dark Side of the Moon... in fact it is all dark." */
denbeste%bbn.com@mitvma.mit.edu (Steven Den Beste) (07/08/89)
Ok, now I feel like a total boob correcting Steven about this baud
thing, only to find that a dozon or so other people (evil Unix-types,
no doubt) already beat me to the, um, punch.
Well, with bits, bauds, and bytes flying around 2400 baud and
2400 bps is escentialy the same thing.
That is, if a random sample of survayed bits do indeed subscribe
to a well respected baud, and we are talking ten bits per character
(seven, around two paraty bits, wraped by one stop bit) and there
isn't unusual sunspot activity and good little data keeps to the right
so to avoid a data collision and possible loss of life THEN just
maybe I can send a message through the internet gateway, beamed
via satalite at 150 baud (or whatever) and somewhere land in the
vicinity of comp.sys.amiga.
It works well over 50 % of the time. I don't know why!
Customer: Why can't this computer talk to that one?
Techie: It's impossible, ok! Now leave me alone, will ya?
/* F. Michael Theilig OHA101 at URIACC.Bitnet
"There is no Dark Side of the Moon...
in fact it is all dark." */thad@cup.portal.com (Thad P Floryan) (07/09/89)
Rahul Dhesi's comments:
" By the way, your definition of "herz" is wrong too; that's what you
write on towels ("hiz" and "herz"). The correct scientific name for
"cycles per second" is "hertz", abbreviated "Hz".
"
reminded me of something circa 1965, when the term "Hertz"/Hz came into vogue.
I was at the Electronic Defense Labs then, working with microwave equipment
whose frequencies were commonly suffixed with "GC" (Giga Cycles). It was
easy to SAY "GC" (gee cee). One person simply could NOT say GigaHertz and
commented (paraphrased):
"Why the f**k couldn't they leave things well enough alone and choose to
honor Charles Proteus Steinmetz (CPS) instead, and retain the abbreviation
``CPS''? Steinmetz' contributions were just as important as Hertz'."
Food for thought, eh? :-)
BTW, <WHICH> "Hertz" was the one honored? I just looked in my dictionary
and found:
"Hertz (herts), Gustav, 1887-1950, German physicist. -- Heinrich, 1857-1894,
German physicist.
"
And one entry further up, I find:
"hertz (hu^rts) [ The "^" should be over the "u"; note the different
pronunciation AND the lower case ] n. Physics. A unit of electromagnetic
wave frequency, equal to one cycle per second. [ after Heinrich Hertz ].
"
And there's also this entry:
"Steinmetz (stin'mets), Charles Proteus, 1865-1923, U.S. Electrical Engineer
born in Germany.
"
Oh well! :-)
I've noticed also the US Metrification Committee has been abandoned, and
speed limit signs and automobile speedometers (in the USA) no longer need to
have the km/h markings. A free beer to whomever guesses what THIS has to do
with the Amiga (and citing the "units" program doesn't count! :-)
Thad Floryan [ thad@cup.portal.com (OR) ..!sun!portal!cup.portal.com!thad ]shadow@pawl.rpi.edu (Deven T. Corzine) (07/11/89)
In article <19246@louie.udel.EDU> denbeste%bbn.com@mitvma.mit.edu (Steven Den Beste) writes: > Well, with bits, bauds, and bytes flying around 2400 baud and > 2400 bps is escentialy the same thing. "2400 baud modem" is technically incorrect, but so entrenched as to be unworthwhile to worry about. Just accept the common usage of "baud" as meaning "bits per seconds" and leave it at that. > That is, if a random sample of survayed bits do indeed subscribe > to a well respected baud, and we are talking ten bits per character > (seven, around two paraty bits, wraped by one stop bit) [...] No. Generally, you will have 1 start bit, either 7 data bits and 1 parity bit, or 8 data bits, and 1 stop bit. [1+7+1+1=10, 1+8+1=10] You COULD have a different configuration, but it is quite rare. Old teletype terminals ran at 110 baud, using 1 start bit, 7 data bits, 1 parity bit, and 2 stop bits, (because of the slow speed of the print head) yielding 11 bits per character, and a throughput of an even 10 characters per second. A 2400 "baud" modem uses 10 bpc for 240 cps, exactly. It is 2400 bps, but the data stream is cut to 1920 bps. (or 1680 with parity checking) This all applies to asynchronous modems, which need the start and stop bits for synchronization and error detection. Synchronous modems are a different situation. Deven -- shadow@[128.113.10.2] <shadow@pawl.rpi.edu> Deven T. Corzine (518) 272-5847 shadow@[128.113.10.201] <shadow@acm.rpi.edu> 2346 15th St. Pi-Rho America deven@rpitsmts.bitnet <userfxb6@rpitsmts> Troy, NY 12180-2306 <<tionen>> "Simple things should be simple and complex things should be possible." - A.K.
new@udel.EDU (Darren New) (07/12/89)
>> (seven, around two paraty bits, wraped by one stop bit) [...] >No. Generally, you will have 1 start bit, either 7 data bits and 1 >parity bit, or 8 data bits, and 1 stop bit. [1+7+1+1=10, 1+8+1=10] This was a joke, everyone. From an old radial tire commercial. Don't bother to beat it into the ground... -- Darren