Communication systems -- Find the Modulation Depth....

In summary, the image shows a modulated signal s(t), with one period of the modulating signal m(t). The mean value of m(t) is equal to zero and its asked me to find the modulated index, amplitude of the carrier, equation of the message(m(t)) and kind of modulation (DSB-SC or AM). The Attempt at a Solution suggests that take the two s(t) signals in "relevant equations" and try to imagine s(t)=A*m(t)*cos*2*pi*fc*t) (dsb-sc modulation) giving you the shown signal. Only one of those two can give you the shown signal and a little thinking should get
  • #1
bonildo
14
1

Homework Statement


Hello, the plot in the image shows a modulated signal s(t), with one period of the modulating signal m(t). The mean value of m(t) is equal to zero . Its asked me to find the modulated index, the amplitude of the carrier, the equation of the message(m(t)) and the kind of modulation (DSB-SC or AM).

Homework Equations


s(t)=A*m(t)*cos*2*pi*fc*t) (dsb-sc modulation)
s(t)= (1+ka*m(t))*cos*2*pi*fc*t) (am modulation)

The Attempt at a Solution


I don't know, I'm really stuck in this exercise.
 

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  • #2
Have you tried plotting those questions with various values of the constants to help learn their meanings?
 
  • #3
Dr. Courtney said:
Have you tried plotting those questions with various values of the constants to help learn their meanings?
Yes, I do. But I can't still figure out a solution for it.

I tried to solve s(0)= (1+ka*m(0)), but I don't know who is m(t)
 
  • #4
the plot in the image shows a modulated signal s(t), with one period of the modulating signal m(t).
The image seems to not show m(t). You are making this difficult for yourself if you ignore the assistance a sketch of the modulating signal will likely give you.

If you are not shown m(t), perhaps you can figure it out, or even "guess" it?
 
  • #5
bonildo said:

Homework Statement


Hello, the plot in the image shows a modulated signal s(t), with one period of the modulating signal m(t). The mean value of m(t) is equal to zero . Its asked me to find the modulated index, the amplitude of the carrier, the equation of the message(m(t)) and the kind of modulation (DSB-SC or AM).

Homework Equations


s(t)=A*m(t)*cos*2*pi*fc*t) (dsb-sc modulation)
s(t)= (1+ka*m(t))*cos*2*pi*fc*t) (am modulation)

The Attempt at a Solution


I don't know, I'm really stuck in this exercise.
I suggest:
take the two s(t) signals in "relevant equations". Take one at a time.
Can you imagine s(t)=A*m(t)*cos*2*pi*fc*t) (dsb-sc modulation) giving you the shown signal?
Can you imagine s(t)= (1+ka*m(t))*cos*2*pi*fc*t) (am modulation) giving you the shown signal?
Only one of those two can give you the shown signal.
And a little thinking should get you the answers you seek.
Hint: only one of your s(t) can produce a signal with differing maxima (5 and 15).
P.S. obviously, m(t) is a sinusoid.
 

Related to Communication systems -- Find the Modulation Depth....

1. What is modulation depth in communication systems?

Modulation depth refers to the measure of how much the amplitude of a carrier signal is varied by a modulating signal in a communication system. It is typically expressed as a percentage or in decibels (dB).

2. Why is modulation depth important in communication systems?

Modulation depth is important because it affects the quality and clarity of the transmitted signal. If the modulation depth is too low, the signal may be weak and difficult to detect, while if it is too high, it may cause distortion and interference.

3. How is modulation depth calculated?

Modulation depth can be calculated by measuring the difference in amplitude between the highest and lowest points of the modulated signal, and then dividing it by the average amplitude of the signal. This value is then expressed as a percentage or in decibels.

4. What factors can affect modulation depth in communication systems?

The modulation depth in a communication system can be affected by various factors such as the type of modulation used, the quality of the transmitter and receiver components, and external interference or noise.

5. Can modulation depth be adjusted in a communication system?

Yes, modulation depth can be adjusted in a communication system by changing the amplitude of the modulating signal or by adjusting the gain of the amplifier. This allows for optimization of the signal strength for better transmission and reception.

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