A PAM signal can be demodulated using

Question

A PAM signal can be demodulated using

1. A. A High pass filter
2. B. A Band pass filter
3. C. A Low pass filter (Correct answer)
4. D. None of the above

Correct Answer

Option C — A Low pass filter

Detailed Solution & Explanation

The correct answer is A Low pass filter.

Key Points

• A PAM (Pulse Amplitude Modulation) signal is demodulated by passing it through a low pass filter.
• The sampled pulse train contains the original baseband signal plus repeated spectral images centred on multiples of the sampling frequency.
• A low pass filter removes those higher-frequency images and lets only the original baseband through, reconstructing the message.

Additional Information

• Recovery is exact only if the Nyquist criterion is satisfied: the sampling rate must be at least twice the highest frequency present in the message signal.
• If the rate is too low the spectral images overlap, producing aliasing, which no filter can subsequently undo.