some basic question about communication

why do we go for modulation?what r the advantages of using high frequency carrier wave? how does a high frequency wave travel large distance?

Reply to
prad
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cuz frequency is less sensitive to perturbations than amplitude.

what r the advantages of using high frequency carrier wave? Higher rate of transmission of information. cf shannon theorem.

Not sure what your question is. Bouncing on the ionosphere maybe ?

vic

Reply to
vic

Another reason is that transmitting a low frequency baseband signal with no modulation will need a large trasmission antenna in radio applications. By modulating the signal with a high frequency carrier u reduce the potential size of this antenna.

--Hage

Reply to
Hage-bai

Please tell us why adding modulation will affect antenna dimensions.

Also, please quote the material to which you are replying so other people can tell more about WTF.

Thanks

Don

Reply to
Don Bowey

will affect antenna dimensions.

you are replying so other people

to make sure i looked up in a book i had lying around:

"Modern Digital and Analog Communication systems" B.P.Lathi

p11.

"For efficient radiation of electromagnetic energy, the radiating antenna should be on the order of one-tenth or more of the wavelength of the signal radiated."

So say i send a signal with a frequency between 100 to 3KHz, your going to have a wavelength on the order of around 100 to 3000KM. So without modulation you would need a extremely large antenna. This is for radio applications.

Reply to
Hage-bai

--
Even though the the process of modulation is multiplication,  the
low frequency  baseband signal isn\'t usually considered to be
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Reply to
John Fields

Thanks, I had not looked at it quite like that.

Don

Reply to
Don Bowey

Smoke and mirrors.!

--
Real Programmers Do things like this.
http://webpages.charter.net/jamie_5
Reply to
Jamie

You'll find plenty of books on the subject.

Graham

Reply to
Pooh Bear

high frequency carrier wave?

Reply to
ruth

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