Bandwidth Efficient Modulation

Digital Communications Systems

This set of Digital Communication online test focuses on “Bandwidth Efficiency Plane and Bandwidth Efficient Modulation”.

1. QPSK is a composite of
a) Two BPSK
b) Three BPSK
c) Two FSK
d) Two M-ary PSK

2. The IF transmission bandwidth of MFSK is
a) M/T
b) T/M
c) 2M/T
d) M/2

3. The bandwidth efficiency of MFSK is
a) M/log2M
b) log2M/M
c) M/log10M
d) log10M/M

4. The bandwidth efficiency increases as M increases.
a) True
b) False

5. The bandwidth efficiency of QFSK is _______ that of BFSK.
a) Greater than
b) Less than
c) Equal to
d) None of the mentioned

6. Which modulation is the most efficient one?
a) BPSK
b) BFSK
c) QPSK
d) QAM

7. The primary communication resource is
a) Transmitted power
b) Received power
c) Efficiency
d) None of the mentioned

8. Greater the redundancy lesser is the bandwidth expansion.
a) True
b) False

9. Which modulation scheme uses nonlinear transponders?
a) MSK
b) Offset QPSK
c) MSK & Offset QPSK
d) None of the mentioned

10. Which modulation requires more bandwidth?
a) QPSK
b) OQPSK
c) BPSK
d) BFSK

11. Which modulation has lower side lobe levels?
a) QPSK
b) OQPSK
c) BPSK
d) MSK

12. Which modulation is spectrally more efficient?
a) BPSK
b) MSK
c) QPSK
d) OQPSK

13. Which modulation spectrum has narrow main lobe?
a) QPSK
b) OQPSK
c) BPSK
d) MSK

14. Which technique can be used for bandwidth reduction?
a) BPSK
b) QPSK
c) MPSK
d) MFSK

15. QPSK amplitude modulates
a) Sine function
b) Cosine function
c) Sine & Cosine function
d) None of the mentioned

16. QAM is a combination of
a) ASK and FSK
b) ASK and PSK
c) PSK and FSK
d) None of the mentioned

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