A modulating signal m (t) = 10 cos (27 x 10°t) is amplitude modulated with a carrier signal c(t) = 50 cos (27 x 10t) . Find the modulation index, the carrier power, and the power required for transmitting AM wave.

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**AM Modulation Problem**

A modulating signal \( m(t) = 10 \cos(2\pi \times 10^3 t) \) is amplitude modulated with a carrier signal \( c(t) = 50 \cos(2\pi \times 10^5 t) \). Find the modulation index, the carrier power, and the power required for transmitting the AM wave.

**Solution Explanation**

1. **Modulation Index (\( \mu \))**: The modulation index is calculated using the formula:

   \[
   \mu = \frac{A_m}{A_c}
   \]

   where \( A_m = 10 \) is the amplitude of the modulating signal and \( A_c = 50 \) is the amplitude of the carrier signal.

   \[
   \mu = \frac{10}{50} = 0.2
   \]

2. **Carrier Power (\( P_c \))**: The carrier power is given by:

   \[
   P_c = \frac{A_c^2}{2R}
   \]

   Assuming the resistance \( R = 1 \, \Omega \), the carrier power is:

   \[
   P_c = \frac{50^2}{2 \times 1} = 1250 \, \text{watts}
   \]

3. **Total Power in AM Wave (\( P_t \))**: The total power transmitted in an AM wave is:

   \[
   P_t = P_c \left(1 + \frac{\mu^2}{2}\right)
   \]

   Substituting the values:

   \[
   P_t = 1250 \left(1 + \frac{0.2^2}{2}\right) = 1250 \left(1 + \frac{0.04}{2}\right) = 1250 \times 1.02 = 1275 \, \text{watts}
   \]

Therefore, the modulation index is 0.2, the carrier power is 1250 watts, and the total power for transmitting the AM wave is 1275 watts.
Transcribed Image Text:**AM Modulation Problem** A modulating signal \( m(t) = 10 \cos(2\pi \times 10^3 t) \) is amplitude modulated with a carrier signal \( c(t) = 50 \cos(2\pi \times 10^5 t) \). Find the modulation index, the carrier power, and the power required for transmitting the AM wave. **Solution Explanation** 1. **Modulation Index (\( \mu \))**: The modulation index is calculated using the formula: \[ \mu = \frac{A_m}{A_c} \] where \( A_m = 10 \) is the amplitude of the modulating signal and \( A_c = 50 \) is the amplitude of the carrier signal. \[ \mu = \frac{10}{50} = 0.2 \] 2. **Carrier Power (\( P_c \))**: The carrier power is given by: \[ P_c = \frac{A_c^2}{2R} \] Assuming the resistance \( R = 1 \, \Omega \), the carrier power is: \[ P_c = \frac{50^2}{2 \times 1} = 1250 \, \text{watts} \] 3. **Total Power in AM Wave (\( P_t \))**: The total power transmitted in an AM wave is: \[ P_t = P_c \left(1 + \frac{\mu^2}{2}\right) \] Substituting the values: \[ P_t = 1250 \left(1 + \frac{0.2^2}{2}\right) = 1250 \left(1 + \frac{0.04}{2}\right) = 1250 \times 1.02 = 1275 \, \text{watts} \] Therefore, the modulation index is 0.2, the carrier power is 1250 watts, and the total power for transmitting the AM wave is 1275 watts.
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