M-ary Signaling and Performance MCQ [Free PDF] – Objective Question Answer for M-ary Signaling and Performance Quiz

1. The limit which represents the threshold Eb/N0 value below which reliable communication cannot be maintained is called as

A. Probability limit
B. Error limit
C. Shannon limit
D. Communication limit

Answer: C

Eb/N0 curve has a waterfall shape. Shannon limit gives the threshold value below which reliable communication cannot be maintained.

 

2. M-ary signalling produces _______ error performance with orthogonal signalling and _______ error performance with multiple phase signalling.

A. Degraded, improved
B. Improved, degraded
C. Improved, improved
D. Degraded, degraded

Answer: B

In M-ary signalling as k increases, the curve moves towards the degraded error performance. It produces improved error performance in the case of orthogonal signalling and degraded error performance in the case of multiple-phase signalling.

 

3. Which is more vulnerable to noise?

A. 2-ary system
B. 4-ary system
C. Binary system
D. None of the mentioned

Answer: B

The minimum energy noise vector for the 4-ary system is smaller than the 2-ary system. So 4-ary system is more vulnerable to noise.

 

4. In which system, the bit stream is portioned into an even and odd stream?

A. BPSK
B. MSK
C. QPSK
D. FSK

Answer: C

In QPSK bit stream is portioned into even and odd streams, I and Q bit streams. Each new stream modulates as an orthogonal component at half bit rate.

 

5. The error performance of MPSK ______ as M or k increases.

A. Increases
B. Decreases
C. Stays constant
D. None of the mentioned

Answer: B

The error performance of MPSK degrades as M or k increases.

 

6. In MPSK adding new signals _______ makes it vulnerable to noise and in MFSK _______ makes it vulnerable.

A. Does, does not
B. Does not, does
C. Does, does
D. Does not, does not

Answer: A

In MPSK adding new signals that are on crowding the signals makes it vulnerable to noise whereas in MFSK it does not.

 

7. In orthogonal signalling with symbols containing more number of bits we need ____ power.

A. More
B. Less
C. Double
D. None of the mentioned

Answer: A

In orthogonal signalling symbols having more number of bits need more power but the requirement per bit is reduced.

 

8. For FSK signalling, WT is equal to

A. 0
B. 1
C. 0.737
D. Infinity

Answer: B

For FSK signalling the detection bandwidth is typically equal to symbol rate 1/T that is WT is nearly equal to 1.

 

9. Energy per symbol Es is given as

A. Es=Eb(log2M)
B. Es=Eb/(log2M)
C. Es=2Eb(log2M)
D. Es=Eb/2(log2M)

Answer: A

In M-ary PSK signalling, the energy per symbol is given as Es=Eb(log2M).

 

10. The relation between the probability of bit error and probability of symbol error in M-ary orthogonal signalling is

A. M/M-1
B. 2M/M-1
C. (M/2)/M-1
D. M/M+1

Answer: C

The relationship between the probability of bit error and probability of symbol error is (M/2)/M-1 in M-ary orthogonal signalling.

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