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What Really Is In Carrier Signal ?

Question asked by Abhishek Rawal in #Coffee Room on Jul 3, 2013
Abhishek Rawal
Abhishek Rawal · Jul 3, 2013
Rank A2 - PRO
As we know, In Analog communication in air medium between two antennas from transmitter to receiver, in transmitter end; the information signal is sent with the carrier signal & modulation is been done. (depends on type of modulation, AM,PM or FM)

We all know that the main concern is the Noise, that gets added in medium.

My question is : Carrier signal is a signal that's been superimposed on information signal, but carrier signal is one type of signal, & every signal do contain some energy thus it is noise.
So, does it mean that in modulation technique, while superimposing carrier signal we're intentionally( or we have to compulsory as there no other to transmit signal to long range) sending Noise alongwith information signal.

What does really this, Carrier signal contains ? No signal is obtained without energy, so there outta be something in carrier signal, what is it ? Posted in: #Coffee Room
Jeffrey Arulraj
Jeffrey Arulraj · Jul 4, 2013
Rank A2 - PRO
Message signal energy is less and so if I transmit a message signal directly through a antenna my range will be really low

So I multiply this signal with a carrier signal which has higher frequency than that of the message signal and so higher energy

This high energy signal does not have any role in the noise produced during transmission

The circuits used for modulation are sources of noise
Harshad Italiya
Harshad Italiya · Jul 4, 2013
Rank A1 - PRO
...Carrier signal is simply added with information signal so it can cover more distance. Information signal is used to be of low frequency so it will need High frequency carrier.

I remember example given by my professor : One paper is your information and you want to throw it. It is not able to clear long distance. Now you put one stone inside paper and throw it. Simple !
Abhishek Rawal
Abhishek Rawal · Jul 4, 2013
Rank A2 - PRO
Okay, I know that carrier signal is used to superimpose on the information signal,withthe parameters like Frequency, Amplitude & Phase for FM,AM & PM respectively, so that it can cover long distance.

My question is : Every signal in the world contains energy, so does carrier signal.
So carrier signal must be containing something, you know.
Some kind of energy, some kind of discrete energy. Which is nothing but noise, isnt it ?
So, what I want to confirm is, aren't we intentionally sending noise signal only ?

I hope you understood what i mean to say.
I want to know that what the hell is it in Carrier signal ?
Harshad Italiya
Harshad Italiya · Jul 4, 2013
Rank A1 - PRO
Yes you can call it noise but that is wanted noise and it has some defined nature so you can predict how long it can travell.

While real noise it unwanted and have no any nature so you can't use it to carry information signal.
Harshad Italiya
Harshad Italiya · Jul 4, 2013
Rank A1 - PRO
I have explained how carrier signal is used to carry information.
Please see both case. You can say both carrier and noise have energy but see resulted modulated signal.
Explain
Anand Tamariya
Anand Tamariya · Jul 4, 2013
Rank B2 - LEADER
Abhishek Rawal
Okay, I know that carrier signal is used to superimpose on the information signal,withthe parameters like Frequency, Amplitude & Phase for FM,AM & PM respectively, so that it can cover long distance.

My question is : Every signal in the world contains energy, so does carrier signal.
So carrier signal must be containing something, you know.
Some kind of energy, some kind of discrete energy. Which is nothing but noise, isnt it ?
So, what I want to confirm is, aren't we intentionally sending noise signal only ?

I hope you understood what i mean to say.
I want to know that what the hell is it in Carrier signal ?
Think of it as encryption - the data is meaningful only if you have appropriate keys; else it's just noise.
Jeffrey Arulraj
Jeffrey Arulraj · Jul 5, 2013
Rank A2 - PRO
Well in short practically we call signal which does not match any criteria set for decrypting as noise

Where as Carrier is noise which can be removed easily without any hinderance or trouble from the message signal

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