GATE EC 2015 Set 3 — Question 32

MCQ+1 / -0.33EasyDigital Modulation (ASK, PSK, FSK, QAM)Digital Modulation & DetectionCommunications

Communications → Digital Modulation & Detection → Digital Modulation (ASK, PSK, FSK, QAM)

Last updated 5 September 2026

Question

The modulation scheme commonly used for transmission from GSM mobile terminals is

Correct answer (D) Gaussian Minimum Shift Keying (GMSK) Solution GSM (Global System for Mobile Communications) uses Gaussian Minimum Shift Keying (GMSK) as its standard modulation scheme. GMSK is a type of continuous-phase frequency shift keying (CPFSK) that uses a Gaussian filter to smooth the phase transitions. This results in a constant envelope signal, which allows the use of power-efficient non-linear (Class-C) power amplifiers in mobile handsets, extending battery life. It also provides good spectral efficiency by reducing side-lobe levels. Turn this into a strength. Explore AI-powered practice and doubt support with Success Tracker.

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Correct answer (D) Gaussian Minimum Shift Keying (GMSK) Solution GSM (Global System for Mobile Communications) uses Gaussian Minimum Shift Keying (GMSK) as its standard modulation scheme. GMSK is a type of continuous-phase frequency shift keying (CPFSK) that uses a Gaussian filter to smooth the phase transitions. This results in a constant envelope signal, which allows the use of power-efficient non-linear (Class-C) power amplifiers in mobile handsets, extending battery life. It also provides good spectral efficiency by reducing side-lobe levels.

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