Official PYQ · 2026Set 1 · Q34Digital CommunicationsMCQ2 marks

GATE EC 2026 Set 1 Q34 — Digital Communications

A QPSK modulated signal from an additive white Gaussian noise (AWGN) channel is received with an $E_{b} / N_{o}=8.4 \mathrm{~dB}$ at the input of a coherent QPSK demodulator. A maximum-likelihood reception method is used in the demodulator.

Assume the complimentary error function
$\operatorname{erfc}(u) \cong[1 /(u \sqrt{\pi})] \exp \left(-u^{2}\right) .$
Which is the nearest bit error rate (BER) at the output of the demodulator?

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Answer: B

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Published 10 Oct 2026

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