In order to recover the original signal from the Sampled one, what is the condition to be satisfied for sampling frequency ωs and highest frequency component ωm

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JKSSB JE Electrical 2015 Official Paper
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  1. ωm < ωs ≤ 2 ωm
  2. ωs ≥ 2 ωm
  3. ωs < ωm
  4. ωs = ωm

Answer (Detailed Solution Below)

Option 1 : ωm < ωs ≤ 2 ωm
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Detailed Solution

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Explanation:

Condition for Sampling Theorem

Definition: The sampling theorem, also known as the Nyquist-Shannon sampling theorem, is a fundamental principle in signal processing. It states that a continuous-time signal can be completely represented and reconstructed from its samples if the sampling frequency satisfies a specific condition in relation to the highest frequency component of the signal.

Statement: To accurately recover the original signal from its sampled version, the sampling frequency (ωs) must be at least twice the highest frequency component (ωm) of the signal. Mathematically, this condition is expressed as:

ωs ≥ 2ωm

This condition ensures that no aliasing occurs during the sampling process, allowing the original signal to be reconstructed without distortion.

Correct Option Analysis:

The correct option is:

Option 2: ωs ≥ 2ωm

This option correctly represents the Nyquist criterion. According to the theorem, the sampling frequency must be at least twice the highest frequency component of the signal (ωm) to prevent aliasing and ensure complete reconstruction of the original signal. If this condition is satisfied, the sampled signal contains all the necessary information to recover the original continuous-time signal.

Additional Information

To further understand the analysis, let’s evaluate the other options:

Option 1: ωm < ωs ≤ 2ωm

This option is incorrect because it suggests that the sampling frequency can be less than twice the highest frequency component (ωm) and still allow accurate signal reconstruction. However, if ωs is less than 2ωm, aliasing occurs, making it impossible to recover the original signal without distortion. The condition ωs ≤ 2ωm does not guarantee the Nyquist criterion is met.

Option 3: ωs < ωm

This option is incorrect because it violates the Nyquist criterion. If the sampling frequency is less than the highest frequency component of the signal, severe aliasing occurs, and the original signal cannot be reconstructed. This condition leads to significant distortion in the sampled signal.

Option 4: ωs = ωm

This option is also incorrect. If the sampling frequency is equal to the highest frequency component of the signal, the Nyquist criterion is not satisfied. In such a case, aliasing still occurs, and the original signal cannot be accurately reconstructed. The sampling frequency must be at least twice the highest frequency component to meet the Nyquist criterion.

Conclusion:

The correct condition for accurately recovering the original signal from its sampled version is ωs ≥ 2ωm. This ensures that the sampling theorem is satisfied, preventing aliasing and enabling complete reconstruction of the original signal. Other options either violate this condition or fail to guarantee the accurate recovery of the signal, leading to distortion or loss of information.

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