M-ary Signalling and Performance

Question 1
Marks : +2 | -2
Pass Ratio : 100%
In which system, bit stream is portioned into even and odd stream?
BPSK
MSK
QPSK
FSK
Explanation:
In QPSK bit stream is portioned into even and odd stream, I and Q bit streams. Each new stream modulates as orthogonal component at half bit rate.
Question 2
Marks : +2 | -2
Pass Ratio : 100%
M-ary signalling produces _______ error performance with orthogonal signalling and _______ error performance with multiple phase signalling.
Degraded, improved
Improved, degraded
Improved, improved
Degraded, degraded
Explanation:
In M-ary signalling as k increases, the curve moves towards the degraded error performance. It produces improved error performance in case of orthogonal signalling and degraded error performance in case of multiple phase signalling.
Question 3
Marks : +2 | -2
Pass Ratio : 100%
The relation between the probability of bit error and probability of symbol error in M-ary orthogonal signalling is
M/M-1
2M/M-1
(M/2)/M-1
M/M+1
Explanation:
The relationship between the probability of bit error and probability of symbol error is (M/2)/M-1 in M-ary orthogonal signalling.
Question 4
Marks : +2 | -2
Pass Ratio : 100%
In MPSK adding new signals _______ make it vulnerable to noise and in MFSK _______ make it vulnerable.
Does, does not
Does not, does
Does, does
Does not, does not
Explanation:
In MPSK adding new signals that is on crowding the signals it makes it vulnerable to noise where as in MFSK it does not.
Question 5
Marks : +2 | -2
Pass Ratio : 100%
Energy per symbol Es is given as
Es=Eb(log2M)
Es=Eb/(log2M)
Es=2Eb(log2M)
Es=Eb/2(log2M)
Explanation:
In M-ary PSK signalling, the energy per symbol is given as Es=Eb(log2M).
Question 6
Marks : +2 | -2
Pass Ratio : 100%
For FSK signalling, WT is equal to
0
1
0.737
Infinity
Explanation:
For FSK signalling the detection bandwidth is typically equal to symbol rate 1/T that is WT is nearly equal to 1.
Question 7
Marks : +2 | -2
Pass Ratio : 100%
Which is more vulnerable to noise?
2-ary system
4-ary system
Binary system
None of the mentioned
Explanation:
The minimum energy noise vector for 4-ary system is smaller than 2-ary system. So 4-ary system is more vulnerable to noise.
Question 8
Marks : +2 | -2
Pass Ratio : 100%
In orthogonal signalling with symbols containing more number of bits we need ____ power.
More
Less
Double
None of the mentioned
Explanation:
In orthogonal signalling with symbols having more number of bits need more power but requirement per bit is reduced.
Question 9
Marks : +2 | -2
Pass Ratio : 100%
The error performance of MPSK ______ as M or k increases.
Increases
Decreases
Stays constant
None of the mentioned
Explanation:
The error performance of MPSK degrades as M or k increases.
Question 10
Marks : +2 | -2
Pass Ratio : 100%
The limit which represents the threshold Eb/N0 value below which reliable communication cannot be maintained is called as
Probability limit
Error limit
Shannon limit
Communication limit
Explanation:
Eb/N0 curve has waterfall shape. Shannon limit gives the threshold value below which reliable communication cannot be maintained.