Bandwidth and Bauds...

i had a looong discution over a Math group where i was encouraged to
post Here.
So, i know this:
i have a digital signal which has 10 PulsesPerSecond, i have a
modulation speed=50Bauds.
Ok, what i need to find out is:
-which is the bandwith requiered to send this signal.
-the fourier spectrum

Things that i was able to find out:
for this signal, frecuency=10hz since period T=1/PperSecond.
and i read that Bauds means "symbol"/sec.

So, i don't understand how this info is going to help me find Bandwith
and spectrum...

Please Help!!!

"ifmusic" <ifmusic@gmail.com> writes:

> i had a looong discution over a Math group where i was encouraged to
> post Here.
> So, i know this:
> i have a digital signal which has 10 PulsesPerSecond, i have a
> modulation speed=50Bauds.
> Ok, what i need to find out is:
> -which is the bandwith requiered to send this signal.
> -the fourier spectrum
>
> Things that i was able to find out:
> for this signal, frecuency=10hz since period T=1/PperSecond.
> and i read that Bauds means "symbol"/sec.
>
> So, i don't understand how this info is going to help me find Bandwith
> and spectrum...
>
> Please Help!!!

Hi ifmusic,

I don't really understand your question. When you say you have a digital
signal which has "10 PulsesPerSecond," are you saying that you have
a stream of information bits that come at a rate of 10 bits per second?

While we know what baud rate is, and thus we understand what 50 Baud is,
it is unusual to speak of baud rate without identifying the underlying
modulation involved. For example, if you use binary phase-shift keying
(BPSK), you can transmit 50 bits per second at 50 baud. If you use
QPSK (Quadrature PSK), you can transmit 100 bits per second at 50 baud.
The spectrum of these two modulation types are different. You really
can't identify the spectrum without specifying the modulation type,
and you haven't told us the modulation type.

Lastly, given a baud rate of 50, you can transmit a minimum of 50
bits per second. So I don't understand why you're using a baud
rate of 50 to transmit 10 bits/second.
-- 
%  Randy Yates                  % "With time with what you've learned, 
%% Fuquay-Varina, NC            %  they'll kiss the ground you walk 
%%% 919-577-9882                %  upon."
%%%% <yates@ieee.org>           % '21st Century Man', *Time*, ELO
http://home.earthlink.net/~yatescr

> I don't really understand your question. When you say you have a digital
> signal which has "10 PulsesPerSecond," are you saying that you have
> a stream of information bits that come at a rate of 10 bits per second?
>
Yes. it's 10bits/sec.

> While we know what baud rate is, and thus we understand what 50 Baud is,
> it is unusual to speak of baud rate without identifying the underlying
> modulation involved. For example, if you use binary phase-shift keying
> (BPSK), you can transmit 50 bits per second at 50 baud. If you use
> QPSK (Quadrature PSK), you can transmit 100 bits per second at 50 baud.
> The spectrum of these two modulation types are different. You really
> can't identify the spectrum without specifying the modulation type,
> and you haven't told us the modulation type.
>
it would be  BPSK.

> Lastly, given a baud rate of 50, you can transmit a minimum of 50
> bits per second. So I don't understand why you're using a baud
> rate of 50 to transmit 10 bits/second.
> -- 
and THAT's exactly what I Do Not Understand about the question.

"ifmusic" <ifmusic@gmail.com> writes:
> [...]
> and THAT's exactly what I Do Not Understand about the question.

You're the question-asker - how can you not understand your own
question??? Did you get the question from somewhere else?

I'm sorry - there seems to be a total disconnect here. Maybe it would
help if you would bump up a level and tell us where this question is
coming from? 
-- 
%  Randy Yates                  % "She's sweet on Wagner-I think she'd die for Beethoven.
%% Fuquay-Varina, NC            %  She love the way Puccini lays down a tune, and
%%% 919-577-9882                %  Verdi's always creepin' from her room." 
%%%% <yates@ieee.org>           % "Rockaria", *A New World Record*, ELO   
http://home.earthlink.net/~yatescr

ifmusic wrote:

(I have restored the original question, since it is apropos to the 
discussion.  And I have edited it somewhat for spelling)

 >>> i had a looong discussion over a Math group where i was encouraged
 >>> to post Here.
 >>> So, i know this:
 >>> i have a digital signal which has 10 pulses per second, i have a
 >>> modulation speed=50Bauds.
 >>> Ok, what i need to find out is:
 >>> -which is the bandwidth required to send this signal.
 >>> -the Fourier spectrum
 >>>
 >>> Things that i was able to find out:
 >>> for this signal, frequency=10hz since period T=1/PperSecond.
 >>> and i read that Bauds means "symbol"/sec.
 >>>
 >>> So, i don't understand how this info is going to help me find
 >>> Bandwidth and spectrum...
 >>>
 >>> Please Help!!!
 >>>

>>I don't really understand your question. When you say you have a digital
>>signal which has "10 PulsesPerSecond," are you saying that you have
>>a stream of information bits that come at a rate of 10 bits per second?
>>
> 
> Yes. it's 10bits/sec.
> 
> 
>>While we know what baud rate is, and thus we understand what 50 Baud is,
>>it is unusual to speak of baud rate without identifying the underlying
>>modulation involved. For example, if you use binary phase-shift keying
>>(BPSK), you can transmit 50 bits per second at 50 baud. If you use
>>QPSK (Quadrature PSK), you can transmit 100 bits per second at 50 baud.
>>The spectrum of these two modulation types are different. You really
>>can't identify the spectrum without specifying the modulation type,
>>and you haven't told us the modulation type.
>>
> 
> it would be  BPSK.
> 
> 
>>Lastly, given a baud rate of 50, you can transmit a minimum of 50
>>bits per second. So I don't understand why you're using a baud
>>rate of 50 to transmit 10 bits/second.
>>-- 
> 
> and THAT's exactly what I Do Not Understand about the question.
> 
Something is just _not_ lining up here.  You can have bit/s > baud, 
because you can stuff more than one bit into one symbol (even 5, if 
you're so inclined).  But it really doesn't make sense to have bit/s < 
baud, because it's kinda hard to have less than one bit per symbol.

You _could_ have a high-rate error-correcting code, that requires five 
bits of redundancy to transmit one bit of information -- but that would 
not usually be expressed as "bit/baud", it would be stated explicitly 
that there is some underlying modulation scheme, with coding laid on top.

Perhaps you could go back to the beginning, and tell us more about what 
you're trying to do, so we can figure out where the disconnect is?

-- 

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

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