Home › Previous year questions › GATE 2016 EC (EC2) › Question 32GATE 2016 EC (EC2) – Question 32 Communications · Digital Communications · 1 mark · Numerical answer
A speech signal is sampled at 8 kHz and encoded in PCM with 8 bits/sample. The PCM data are transmitted over a baseband channel using 4-level PAM. The minimum bandwidth in kHz is ________.
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Show answer and explanation Correct answer: 15.9 to 16.1
Explanation The bit rate is $8000\cdot8=64000$ bits/s. Four PAM levels carry $\log_2 4=2$ bits per symbol, giving 32000 symbols/s.
Ideal zero-roll-off Nyquist signaling needs baseband bandwidth equal to half the symbol rate. Thus $B_{min}=32000/2=16000$ Hz, or **16 kHz**.
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