29 Mar
1999
29 Mar
'99
4:27 p.m.
At 21:27 29/03/99 -0800, Sellam Ismail wrote:
On Mon, 29 Mar 1999, Bruce Lane wrote:
No, Baud and BPS are different. Baud is the number of signalling changes
per second. Normally, each signal change gives one bit and then Baud ==
BPS, but if you encode more than one bit per signal change then they are
not the same. This is easily achieved if you have different voltages mean
different values. For example, if you use -10V, -5V, 5V and 10V to encode
0, 1, 2 and 3 then the bit rate is twice the baud rate.
Huw Davies | e-mail: Huw.Davies(a)latrobe.edu.au
Information Technology Services | Phone: +61 3 9479 1550 Fax: +61 3 9479
1999
La Trobe University | "If God had wanted soccer played in the
Melbourne Australia 3083 | air, the sky would be painted green"
Actually, ASR-33's ran at 110 Baud rather
than BPS.
Same difference. 
29 Mar
29 Mar
4:40 p.m.
On Tue, 30 Mar 1999, Huw Davies wrote:
No, Baud and BPS are different. Baud is the number of
signalling changes
per second. Normally, each signal change gives one bit and then Baud ==
BPS, but if you encode more than one bit per signal change then they are
not the same. This is easily achieved if you have different voltages mean
different values. For example, if you use -10V, -5V, 5V and 10V to encode
0, 1, 2 and 3 then the bit rate is twice the baud rate.
My ignorance stands naked as the day I was born.
Sellam Alternate e-mail: dastar(a)siconic.com
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30 Mar
30 Mar
1:32 a.m.
At 04:27 PM 3/30/99 +1000, Huw Davies wrote:
At 21:27 29/03/99 -0800, Sellam Ismail wrote:
It is also quite true of modern telephone modems, which are
packing several bits per signal change.
On Mon, 29 Mar 1999, Bruce Lane wrote:
No, Baud and BPS are different. Baud is the number of signalling changes
per second. Normally, each signal change gives one bit and then Baud ==
BPS, but if you encode more than one bit per signal change then they are
not the same. Actually, ASR-33's ran at 110 Baud rather
than BPS.
Same difference. My ignorance stands naked as the day I was born.
Hey! What kind of list do you think this is? :-)
- John
3:04 a.m.
No, Baud and BPS are different. Baud is the number of
signalling changes
But they aren't different on ASR-33s, nor on the modems that were normally
used on ASR-33s (Bell 103 equivalent).
In common usage, the baud rate was generally equal to the BPS until the
introduction of phase shift keying and quadrature amplitude modulation.
For full-duplex use on the PSTN, this happened when the Vadic 3400 and
Bell 212 were introduced. But there were earlier PSK modems for leased
line use, such as the Bell 208.
If someone tries to sell you a 9600 baud modem, you should whack them
with a clue stick. :-)
10:07 a.m.
At 17:04 30/03/99 +0000, Eric Smith wrote:
Hey, I was only being pedantic :-) I quite often use the wrong terminology
too (like 9600 baud modems for example, although I don't refer to 56K
modems as 56K baud - well, hardly ever :-)
There used to be a standard question in one of the Computer Science courses
I took where you had to know the difference - caught lots of students out
with that one!
Huw Davies | e-mail: Huw.Davies(a)latrobe.edu.au
Information Technology Services | Phone: +61 3 9479 1550 Fax: +61 3 9479
1999
La Trobe University | "If God had wanted soccer played in the
Melbourne Australia 3083 | air, the sky would be painted green"
No, Baud and
BPS are different. Baud is the number of signalling changes
But they aren't different on ASR-33s, nor on the modems that were normally
used on ASR-33s (Bell 103 equivalent). 
31 Mar
31 Mar
8:16 a.m.
> No, Baud and BPS are different. Baud is the
number of signalling changes
If someone tries to sell you a 9600 baud modem, you
should whack them
with a clue stick. :-)
I have an 7 KBaud modem over here so, where's your stick ?
(Hint: server side of an 56K analouge dial in :)
(small print: the calculation can be done different :)
Gruss
H.
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HRK
8:38 a.m.
I wrote:
If someone tries to sell you a 9600 baud modem, you
should whack them
with a clue stick. :-)
Hans Franke wrote:
I have an 7 KBaud modem over here so, where's your
stick ?
(Hint: server side of an 56K analouge dial in :)
My clue stick doesn't easily reach Germany from here. And anyhow, a 7 KBaud
modem isn't a 9600 baud modem.
And actually, I believe you're mistaken. The 56K modems (limited to 53K in
the US) use 8000 baud, with a maximum of 7 bits per baud (i.e., a maximum
of 128 constellation points).
It used to be possible to buy a very nice wooden clue stick from HP,
part number 19511-80014. It was advisable to sand at least one end of it,
or use gloves when handing it. My friend Ken prefers the designation "HP
Engineer's Corrective Action Tool", but AFAIK it iss basically the same
thing. :-)
Eric
10:15 a.m.
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10:56 a.m.
Are you claiming that it's impossible to have a
modem where there are
9600 transitions/second on the 'line' side? Because if so, I don't
believe you.
I'm claiming that it's not possible to have a 9600 baud modem on a POTS
line. Obviously it is possible on other transmission lines or media with
greater bandwidth.
What was the official use of this stick? Some kind of
packing/transit
clamping device?
Yes.
10:49 p.m.
> Are you claiming that it's impossible to have
a modem where there are
> 9600 transitions/second on the 'line' side? Because if so, I don't
> believe you.
I'm claiming that it's not possible to have a
9600 baud modem on a POTS
line. Obviously it is possible on other transmission lines or media with
greater bandwidth.
Hmm, now we run again in definition problems. POTS is about
analouge transmition, but the media isn't as clear as you might
think. Depending on the kind of connection, and the used the
bandwidth may reach up beyond 30 kHz, alowing rates of more than
100 Kbps transmission - remember, POTS starts as direct coupled
line until the PBX, now ifthis is a _real_ old PBX and the partner
is on the same PBX there are only the amplifiers to reduce bandwide.
If it is a _real_ old (pre 1938) long distance line again the bandwide
is only limited by the bandwidth of the amplifiers (since the cables
are normaly usable beyond them - exeptions may occure, but thats a
different storie, which I had to learn the hard way). Only if there
are filters inbetween, which are only necersary if the signal is
going to be multiplexed for high capacity long distance lines (and
radio connections) the Bandwidth is reduced.
But in fact, this is all history, POTS no longer exists over here
since years.
Gruss
H.
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HRK
1 Apr
1 Apr
4:52 a.m.
New subject: telephone bandwidth (was Re: ASR-33 Data Format?)
Hans wrote:
POTS is about analouge transmition, but the media
isn't as clear as
you might think. Depending on the kind of connection, and the used the
bandwidth may reach up beyond 30 kHz, alowing rates of more than
100 Kbps transmission - remember, POTS starts as direct coupled
In the US, POTS service is bandlimited to roughly 300-3300 Hz. The
local loop (between you and the CO) has more bandwidth, which is why
it can (sometimes) be used for ISDN or DSL, but the switched voice
network does not.
The phone companies here have offered special leased lines with higher
bandwidth that were used for such things as links between studios and
broadcast facilities. But even though those were analog, they were (by
definition) not POTS. Nowdays those facilities have largely been replaced
by digital leased lines.
I was of the impression that POTS in the rest of the world worked
similarly, but I could easily be mistaken about that.
But in fact, this is all history, POTS no longer
exists over here
since years.
Really? You can't use cheap analog telephones any more? I knew ISDN
was more widely deployed in some other countries than in the US, but I
had no idea that it had completely displaced POTS.
Even so, however, if you use an ISDN B channel for a voice bearer to carry
alaw or mulaw audio samples, you still can't get more than 8000 baud through
it in any particularly useful or effective manner.
The actual baud rate of the raw ISDN BRI varies. In the US it uses 2B1Q
signalling, with a rate of 80 Kbaud in each direction. Other countries
use other signalling schemes, such as 4B3T. IIRC, Germany uses a different
scheme than most of Europe. However, in most countries the telephone
company provides the ISDN NT1, so the customer equipment is connected to
the S/T interface, which is the same worldwide.
Eric
8:03 a.m.
New subject: telephone bandwidth (was Re: ASR-33 Data Format?)
> POTS is about analouge transmition, but the media
isn't as clear as
> you might think. Depending on the kind of connection, and the used the
> bandwidth may reach up beyond 30 kHz, alowing rates of more than
> 100 Kbps transmission - remember, POTS starts as direct coupled
In the US, POTS service is bandlimited to roughly
300-3300 Hz.
AFAIR over here it's 300-3000 Hz (to fit within a 3000 Hz chanel when
multiplexed, together with a 200 Hz signaling chanel)
The
local loop (between you and the CO) has more bandwidth, which is why
it can (sometimes) be used for ISDN or DSL, but the switched voice
network does not.
I tried to bring in _real_ old switches :)
I was of the impression that POTS in the rest of the
world worked
similarly, but I could easily be mistaken about that.
If you take POTS just as the minimum standard as suportet
(almost) everywhere, you're right, but thruout the years
there have been several diferent technologies used and it
was (before the network was completly digitalised) possible
to find different situations if you tried things outside
the guaranteed bandwidth. (And sometimes you even had lines
where not even the guaranteed signaling was possible.)
> But in fact, this is all history, POTS no longer
exists over here
> since years.
Really? You can't use cheap analog telephones any
more? I knew ISDN
was more widely deployed in some other countries than in the US, but I
had no idea that it had completely displaced POTS.
Shure, you can still get an analouge line, but this is only analogue
until the next switch - sometimes they even insall an ISDN-NT in your
basement with an integrated a/b adaptor to fullfill the request. The
last (partly) analouge switch has been abdoned here in Germany some two
years ago.
The situation varies within Europe, Germany just jumped first on
the ISDN trail.
Even so, however, if you use an ISDN B channel for a
voice bearer to carry
alaw or mulaw audio samples, you still can't get more than 8000 baud through
it in any particularly useful or effective manner.
Speaking of chanels - there is also a neat offering for the D channel:
A permenent X25 connection with no time based payment. Neat if you got low
data rates but round the clock availability (up to 9600 bps).
The actual baud rate of the raw ISDN BRI varies. In
the US it uses 2B1Q
signalling, with a rate of 80 Kbaud in each direction. Other countries
use other signalling schemes, such as 4B3T. IIRC, Germany uses a different
scheme than most of Europe. However, in most countries the telephone
company provides the ISDN NT1, so the customer equipment is connected to
the S/T interface, which is the same worldwide.
Within the system even in Germany there are different signalings, but
thats without any influence, thanks to the NT - but even here Germany
had it's own protocoll (1TR6) - thats the curse of beeing early. But
nowadays 1TR6 is only available on special request for compatibility
issues (Sad, since it had some realy neat features).
Gruss
H.
ObCC: Has anyone an issue of Captain Zilog for sale (or is willing
to provide a colour copy) ?
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Ich denke, also bin ich, also gut
HRK
9:01 a.m.
New subject: telephone bandwidth (was Re: ASR-33 Data Format?)
Hans wrote:
Shure, you can still get an analouge line, but this is
only analogue
until the next switch - sometimes they even insall an ISDN-NT in your
basement with an integrated a/b adaptor to fullfill the request.
Well, they do that here also. But the point is that the service that they
are selling to the customer is still POTS. The fact that the line goes
digital somewhere inside the "network cloud" is irrelevant. If you want
to send modem signals through it, they get bandlimited to 300-3300 Hz.
But
nowadays 1TR6 is only available on special request for compatibility
issues (Sad, since it had some realy neat features).
Yes, we have the same problem here with AT&T 5ESS Custom, which was much
nicer than Bellcore National ISDN 1 (NI1).
2:57 a.m.
Eric Smith <eric(a)brouhaha.com> wrote:
I agree, it isn't possible to do 9600 transitions/second
on a POTS line. 9600 baud modems don't do 9600 transitions/second,
they encode more information with what is called quadrature
encoding. Don't confuse data encoding rates with transition
rates, they aren't the same.
Dwight
Are you
claiming that it's impossible to have a modem where there are
9600 transitions/second on the 'line' side? Because if so, I don't
believe you.
I'm claiming that it's not possible to have a 9600 baud modem on a POTS
line. Obviously it is possible on other transmission lines or media with
greater bandwidth.
What was the official use of this stick? Some
kind of packing/transit
clamping device?
Yes.
9167
days inactive
9169
days old
13 comments
7 participants
participants (7)
-
ard＠p850ug1.demon.co.uk -
dastar＠ncal.verio.com -
elvey＠hal.com -
eric＠brouhaha.com -
H.Davies＠latrobe.edu.au -
Hans.Franke＠mch20.sbs.de -
jfoust＠threedee.com