Where would be the Information in Signal?

[vmaxusb]

Hello,
I want to know where will be the useful Information In signal?
would it be In amplitude/Phase/Frequency etc ?
Can any one explain me How the Information is associated with all above parameters?

Thank you...
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vmax

 

[FvM]

Can be all of these parameters or nothing (noise). I sugest to consult a communication or signal theory textbook.

 

[halls]

Well, information can be in any of those parameters. Imagine you have to send a value of 100101 for example. You can send a signal which has two levels, 5V and 0V. When the measured value is 5V it is considered as a 1, and when it's 0v, it's considered as a 0.

In the same way, you can have a sinusoidal signal with constant amplitude. When the signal's frequency is 100 kHz it represents a 1 (for example) and if it is 50 kHz it represents a 0, then you will have a frequency changing signal.

The same idea for the phase.

That's why the most basic modulation techniques are AM (amplitude modulation), FM (frequency modulation) and PM (phase modulation), because depends on where the information is being delivered.

 

[asoom]

as halls mentioned it depends on the type of modulation used in the transmitter.

 

[Dmitrij]

You should realize, that the completely determined wave, such as s(t) = Acos(wt+phi) doesn't contain any useful information, because all the parameters of the function given are determined and exact, therefore there is no need of transmitting such signal, as no new information will be obtained from it at the receiving side (everything, including amplitude, phase and frequency, is known).

However, if one of these parameters changes somehow, we say, that it's modulated in accordance with the informative message. Thus, different types of modulation become actual and they correspond to time-varying of different parameters. At the receiving side we demodulate the signal and find out the law of information changing. This changing may be connected with different physical processes, such as, for example, temperature, humidity, pressure varyings and etc. The key idea is that WE GET KNEW KNOWLEDGE.

With respect,

Dmitry