Modem Baud Rate - There ain't no such animal.

Modem Baud Rate - There ain't no such animal.

Post by Alan Fowl » Sat, 30 Jun 2001 17:08:22



        Just a small technical point.
        Data transmission speed is measured in "Bauds"

        Baud rate is Bauds per second, i,e an acceleration.

        Because of the confusion from this misuse, Baud has
been replaced by symbol/s - ITU-T Recommendation B.14 and
the new American Telecommunication Glossary 2000.

http://www.its.bldrdoc.gov/projects/telecomglossary2000/

        So "Baud rate" is really the same as saying symbols
per second per second.

        I have never seen a data rate change slowly from one
speed to another.  They always happen in discreet steps such
as 38,400,  57,600 or 115,400 bit/s  

                regards, Alan

 
 
 

Modem Baud Rate - There ain't no such animal.

Post by Tony Cru » Sun, 01 Jul 2001 07:48:00



> Just a small technical point.
> Data transmission speed is measured in "Bauds"

Alan,

If we're going to nit-pick, then, by golly, let's get it right!  :-)

Data transmission speed is measured in bits per second.

SIGNAL TRANSITION speed, often mis-nomed "symbol rate" by
non-electrical engineering types is measured in Baud.  [sans the "s"]

The ITU Standards folks did a great job of adding to the confusion
by using ambiguous terms such as "symbol" rather than something
a bit more specific such as signal transition [which is typically
amplitude (old), or a combination of amplitude and phase [e.g., QUAM - more
modern].

Quote:

> Baud rate is Bauds per second, i,e an acceleration.

Although you're technically correct, there's no room for
physics here.  :-)  "Baud rate" is a loose use of the English
language and is taken to mean:  "Rate measured in Baud."  Poor,
but countless books use [or misuse] the convention.  I agree this
doesn't make it right, but it's the way it is.  ;-)

<SNIP>

--

In HIS Service,

Tony Cruz  (W8OKX - ex WN2OKX, WA2OKX, CT1EGV)
Remember, there are three kinds of mathematicians:  Those who can
count...and those who can't.

 
 
 

1. ** Table of baud rates for different "uucp 'g'" parameters

We uses some modification of BSD UUCP (UUCP KIAE) on KIAE!
back-bone in network 'RELCOM', and transfere more then 200 Mb
of messages (>20000 mail's and news) using MicroVax-III and V22bis (mainly) and
T2500 (PEP, V32) modems. This UUCP allows me to cahnge window and
packet sizes on each size of connection: I writes simple

 kiae1! ANY Acu,g(5,256)/g(3,128) ...

to set up this parameters.
And, while the working with this UUCP, I made interesting measurements -
how does depend average baud rate from packet and window sizes. May be, it
is interesting.

I transfered 45.5 Kb text file (gdial.c, universal dialer for this uucp)
between MicroVaxes-III, from hardly loaded kiae! (LA about 6 - 8) to
kiae1! (LA about 1). I used modified tty.c driver with increased
limit of rawq from 256 to 1024 chars.
I used very good Iskra-II phone network.

Results:
1) V42bis compression, V32 protocol:
Window Packet Time(sec) Bytes/sec
----------------------------
3      64     79.44    572
6      64     58.16    779
3     128     46.38    963
6     128     34.5     1311
3     256     31.9     1414
6     256     31.5     1436
-----------------------------
2) V42bis compression, V22bis protocol:
Window Packet Time(sec) Bytes/sec
----------------------------
3      64    163.72    277
6      64    132       343
3     128    122       371
6     128    104.37    433
3     256     98.3     462
6     256     95.2     476
3     512     92.7     486
-----------------------------
2) MNP-5  compression, V22bis protocol:
Window Packet Time(sec) Bytes/sec
----------------------------
3      64    212       213
6      64    235       192
3     128    151       299
6     128    177       255
3     256    132       343
6     256    132       343
-----------------------------

If you have standart (HDB System V.3 or Ultrix or BSD)
uucp, and the other side have tha same,
the only thing that you can do is to increase packet size received
by you uucp from 64 to 128 bytes and you window from 3 to 6 (or 7) by 'adb'.
The reason is that this uucp does contain hight limit of packet
size == 128 due to limit of output buffer size (#define MAXBUFSIZE 128).

This binary hack can increase you baud-rate in 1.2 - 2 times.
If you use taylor of HDB 5.4 or simular uucp, you can set
(4,256) parameter of 'g' protocol, and in this case you use all
modem's possibilities.

===================================

2. Command prompt modem access.

3. So, ZyXEL's new modems are delayed, and it ain't the software...

4. NetworkInterface Error Code

5. JDR's 2400 baud modem/4800 baud fax card

6. PubkeyAuthentication

7. What About 2400 Baud (was Let's Build 9600 Baud Modems!)

8. Timing problem

9. Why don't I get higher baud rate than 19200!

10. Diff. b/w setting a port's baud rate from SMIT and ioctl ?

11. problem with USR's baud rate

12. BBS Can't Detect Correct Baud Rate

13. Baud rate for various bps rates