Intersymbol Interference

Digital Communications Systems

This set of Digital Communications Multiple Choice Questions & Answers (MCQs) focuses on “Intersymbol interference 1”.

1. The method in which the tail of one pulse smears into adjacent symbol interval is called as
a) Intersymbol interference
b) Interbit interference
c) Interchannel interference
d) None of the mentioned

2. If each pulse of the sequence to be detected is in _____ shape, the pulse can be detected without ISI.
a) Sine
b) Cosine
c) Sinc
d) None of the mentioned

3. What is symbol rate packing?
a) Maximum possible symbol transmission rate
b) Maximum possible symbol receiving rate
c) Maximum bandwidth
d) Maximum ISI value allowed

4. A nyquist pulse is the one which can be represented by _____ shaped pulse multiplied by another time function.
a) Sine
b) Cosine
c) Sinc
d) None of the mentioned

5. Examples of nyquist filters are
a) Root raised cosine filter
b) Raised cosine filter
c) Root raised & Raised cosine filter
d) None of the mentioned

6. The minimum nyquist bandwidth for the rectangular spectrum in raised cosine filter is
a) 2T
b) 1/2T
c) T2
d) 2/T

7. Roll off factor is the fraction of
a) Excess bandwidth and absolute bandwidth
b) Excess bandwidth and minimum nyquist bandwidth
c) Absolute bandwidth and minimum nyquist bandwidth
d) None of the mentioned

8. Which value of r (roll off factor) is considered as Nyquist minimum bandwidth case?
a) 0
b) 1
c) Infinity
d) None of the mentioned

9. A pulse shaping filter should satisfy two requirements. They are
a) Should be realizable
b) Should have proper roll off factor
c) Should be realizable & have proper roll off factor
d) None of the mentioned

10. Examples of double side band signals are
a) ASK
b) PSK
c) ASK & PSK
d) None of the mentioned

11. The likelihood ratio test is done between
a) Likelihood of s1 by likelihood of s2
b) Likelihood of s2 by likelihood of s1
c) Likelihood of s1 by likelihood of s1
d) None of the mentioned

12. According to the rule of minimizing the error probabilities, the hypothesis should be like if the priori probabilities are ________ than the ratio of likelihoods.
a) Lesser
b) Greater
c) Equal
d) None of the mentioned

13. The detector that minimizes the error probability is called as
a) Maximum likelihood detector
b) Minimum likelihood detector
c) Maximum & Minimum likelihood detector
d) None of the mentioned

14. For a M-ary signal or symbol the number of likelihood functions are
a) M
b) M+1
c) M-1
d) 2M

15. An error in binary decision making occurs when the channel noise is
a) Greater than the optimum threshold level
b) Lesser than the optimum threshold level
c) Greater or Lesser than the optimum threshold level
d) None of the mentioned

16. Optimum threshold value is given by
a) a0+a1/2
b) a0-a1/2
c) a0/2
d) a1/2

17. The symbol of the probability under the tail of Gaussian pdf is called as
a) Complementary error function
b) Co error function
c) Complementary error & Co error function
d) None of the mentioned

18. Matched filter provides _____ signal to noise ratio.
a) Maximum
b) Minimum
c) Zero
d) Infinity

19. The impulse response of the filter is the ________ of the mirror image of the signal waveform.
a) Delayed version
b) Same version
c) Delayed & Same version
d) None of the mentioned

20. Example for antipodal bandpass signaling is
a) BPSK
b) ASK
c) FSK
d) MSK

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