How does information travel in double sideband which is without a carrier?

[vjfaisal]

hi

i want to know that in dsb (double sideband), the carrier is remove ,, how it remove, without it how information travel.
please explain the these issues. clearly if anybody knows.



best regards

 

[echo47]

in double sideband!!!!!!!!!!!!!!11

"Double sideband" modulation has a carrier. Perhaps you meant "double sideband suppressed carrier".

The information is contained in the sidebands, not in the carrier. Removing the carrier saves transmitter power, but it usually complicates the detection process in the receiver.

Here is a very basic description:
https://en.wikipedia.org/wiki/Double_sideband
A few more Google hits:
https://www.st-andrews.ac.uk/~jcgl/Scots_Guide/RadCom/part9/page4.html
https://www.angelfire.com/electronic/funwithtubes/Basics_06_Mod.html

 

[samasimo]

Re: in double sideband!!!!!!!!!!!!!!11

I think the term "carrier" may be misleading in the case of DSB

Carrier= carrier frequency = frequency at whch the signla is modulated (shifted to)

In case of converntional Amplitude modulation. They used to add the informtion to the amplitude of the carrier wave resulting in 2 side bads at both sides of the frequency and a pulse a the carrier frequency (refer to the frequency spectrum of AM).

Later they discovred tha the information lies in the side bands and there is no info at exactly the carrier frequency. The impulse at Fc is a waste of power and decreases the effeciency so they come up with the DSB-SC (ie removed the carrier component) to reduce the power WITHOUT any loss in the info

Amplitude modulated signal= (Ac + m(t)) cos (Wc t)= Ac cos (Wc t)+m(t) cos (Wc t)
so when we remove the first term, we will not have any loss in the information but have gain in terms of power consumption.

the only disadvange of DSB-SC is the decoding complexity. we have to use coherent detection as the simple envelop detector cannot work without the carrier component

 

[safwatonline]

in double sideband!

the idea is that u don't put it in the first place , not to put it then remove it , i.e. u upconverge the data without sending power at the carrier freq.