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The total power content of an AM signal ...

The total power content of an AM signal is 3000 w. For `100%` modulation, the power of CW and that of each side band are,

A

2kW, `0.5` kW

B

3 kw, `0.75` kW

C

4 KW, 1 kW

D

2 KW, 1 kW

Text Solution

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The correct Answer is:
To solve the problem, we need to find the power of the carrier wave and the power of each sideband for an AM signal with a total power of 3000 W and 100% modulation. ### Step-by-Step Solution: 1. **Understand the Total Power in AM Signal**: The total power \( P_t \) in an AM signal is given as 3000 W. 2. **Define Modulation Index**: For 100% modulation, the modulation index \( \mu \) is equal to 1. 3. **Use the Power Relation in AM**: The total power \( P_t \) in an AM signal can be expressed as: \[ P_t = P_c \left(1 + \frac{\mu^2}{2}\right) \] where \( P_c \) is the power of the carrier wave. 4. **Substitute Known Values**: Substitute \( P_t = 3000 \, \text{W} \) and \( \mu = 1 \): \[ 3000 = P_c \left(1 + \frac{1^2}{2}\right) \] This simplifies to: \[ 3000 = P_c \left(1 + 0.5\right) = P_c \times 1.5 \] 5. **Solve for Carrier Power \( P_c \)**: Rearranging gives: \[ P_c = \frac{3000}{1.5} = 2000 \, \text{W} \] Therefore, the power of the carrier wave \( P_c \) is 2000 W. 6. **Calculate Power of Sidebands**: The total power in the sidebands \( P_{sb} \) can be calculated as: \[ P_{sb} = P_t - P_c = 3000 - 2000 = 1000 \, \text{W} \] 7. **Determine Power of Each Sideband**: Since there are two sidebands in AM, the power of each sideband \( P_{sb} \) is: \[ P_{sb} = \frac{1000}{2} = 500 \, \text{W} \] ### Final Results: - Power of Carrier Wave \( P_c = 2000 \, \text{W} \) (or 2 kW) - Power of Each Sideband \( P_{sb} = 500 \, \text{W} \) (or 0.5 kW) ### Conclusion: The correct answer is: - Carrier Power: 2 kW - Each Sideband Power: 0.5 kW
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