What is the difference between multiplexing and modulation?

Hi! Thanks for the question.

Whatis.com provides a very good comparison of modulation and multiplexing.


Modulation -  "In a modem, the modulation process involves the
conversion of the digital computer signals (high and low, or logic 1
and 0 states) to analog audio-frequency (AF) tones...The demodulation
process converts the audio tones back into digital signals that a
computer can understand. directly."


Multiplexing - "More information can be conveyed in a given amount of
time by dividing the bandwidth of a signal carrier so that more than
one modulated signal is sent on the same carrier. "


"modulation"
http://searchnetworking.techtarget.com/sDefinition/0,,sid7_gci212586,00.html

"multiplexing"
http://searchnetworking.techtarget.com/sDefinition/0,,sid7_gci212614,00.html


Search terms used:  
multiplexing modulation

I hope these links would help you in your research. Before rating this
answer, please ask for a clarification if you have a question or if
you would need further information.
                             
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Easterangel-ga                              
Google Answers Researcher

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Request for Answer Clarification by manobik-ga on 16 Apr 2005 18:00 PDT

I wanted some concrete DIFFERENCE. 

like 

1. Modulation can not send multiple signal simultenously over one
communication channel but Multiplexing can.

2. Modulation can be applied to direct current, to alternating
current, and to optical signals. What about Multiplexing ???

Will u provide me some points like these ?

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Clarification of Answer by easterangel-ga on 16 Apr 2005 18:32 PDT

Hi again!

My original answer was a reply to your original question as regards to
the difference. I did not presume you want a lsit of the specific
differences. Anyway here are some differences I was able to find.

This resource from the Washington State University website provides a
very good discussion of multiplexing and modulation.

- In modulation one conversation can only be carried at one time while
Multiplexing allows multiple conversations.

- Modulation is appropriate for a small population only while
Multiplexing allows for communication for larger populations.

- Modulation is appropriate only for short distances while longer ones
would be more suitable for multiplexing.

- In multiplexing the total frequency bandwidth is divided into
channels enabling multiple signals to be sent in a period of time. In
modulation only one signal can be sent at a time.

"ICT Technologies"
http://cbdd.wsu.edu/kewlcontent/cdoutput/TR502/index.htm

I hope this would be of help.

Thanks!