For a noiseless channel of bandwidth 3 kHz transmitting binary level signals, what is the maximum theoretical data rate according to the Nyquist criterion?

Difficulty: Easy

Correct Answer: 6 Kbps

Explanation:


Introduction / Context:
The Nyquist criterion provides an upper bound on the data rate for a noiseless channel given a limited bandwidth and a specified number of discrete signaling levels. This question asks you to apply the Nyquist formula to a 3 kHz channel using binary signaling (two levels) to find the maximum bit rate in bits per second (bps).


Given Data / Assumptions:

  • Channel bandwidth B = 3 kHz (that is, 3000 Hz).
  • Number of signal levels M = 2 (binary).
  • The channel is idealized as noiseless; intersymbol interference is neglected under Nyquist sampling.


Concept / Approach:
Nyquist maximum data rate for a noiseless channel is given by: R_max = 2 * B * log2(M) For binary signaling (M = 2), log2(2) = 1, so the formula simplifies to: R_max = 2 * B Substituting B = 3000 Hz yields 6000 bps, which is 6 Kbps.


Step-by-Step Solution:

Write the formula: R_max = 2 * B * log2(M)Insert values: R_max = 2 * 3000 * log2(2)Compute log2(2) = 1 → R_max = 2 * 3000 * 1Compute numeric result: R_max = 6000 bps = 6 Kbps


Verification / Alternative check:
Compare with higher-level modulation: if M = 4 (quaternary), R_max would double to 12 Kbps for the same bandwidth, confirming that binary (M = 2) gives 6 Kbps at 3 kHz.


Why Other Options Are Wrong:

  • 3 Kbps: Misses the factor of 2 in the Nyquist formula for baseband signaling.
  • 12 Kbps / 24 Kbps: These would require higher M (more levels) or additional assumptions; they exceed the binary case.
  • None of the above: Incorrect because 6 Kbps is exactly the Nyquist limit here.


Common Pitfalls:
Confusing Nyquist's noiseless limit with Shannon's noisy-channel capacity, or forgetting that binary signaling (M = 2) makes log2(M) equal to 1.


Final Answer:
6 Kbps

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