Four messages band-limited to W, W, 2W, and 3W respectively are to be multiplexed using Time Division Multiplexing (TDM).
The minimum bandwidth required for transmission of this TDM signal is:
Options:
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(a) W
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(b) 3W
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(c) 6W
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(d) 7W
Solution: Minimum Bandwidth for TDM
For a band-limited signal of bandwidth B, the minimum sampling rate required is 2B (Nyquist criterion).
Sampling rates of the four messages:
- Bandwidth W → Sampling rate = 2W
- Bandwidth W → Sampling rate = 2W
- Bandwidth 2W → Sampling rate = 4W
- Bandwidth 3W → Sampling rate = 6W
Total sampling rate: 2W + 2W + 4W + 6W = 14W
In TDM, the minimum required transmission bandwidth is half the total sampling rate:
Required Bandwidth = 14W / 2 = 7W
Correct Answer: (d) 7W