Equalization and Non Coherent Detection

Digital Communications Systems

This set of Digital Communication test focuses on “Equalization and Non Coherent Detection”.

1. The range of amplitude difference gives the value of
a) Width
b) Distortion
c) Timing jitter
d) Noise margin

2. As the eye opens, ISI _______
a) Increases
b) Decreases
c) Remains the same
d) None of the mentioned

3. Pseudo noise signal has _______ and _______ SNR for the same peak transmitted power.
a) Larger, smaller
b) Smaller, larger
c) Larger, larger
d) Smaller, smaller

4. The index value n, in transversal filter can be used as.
a) Time offset
b) Filter coefficient identifier
c) Time offset & Filter coefficient identifier
d) None of the mentioned

5. The over-determined set of equations can be solved using
a) Zero forcing
b) Minimum mean square error
c) Zero forcing & Minimum mean square error
d) None of the mentioned

6. If the filter’s tap weight remains fixed during transmission of data, then the equalization is called as
a) Preset equalization
b) Adaptive equalization
c) Fixed equalization
d) None of the mentioned

7. Equalization method which is done by tracking a slowly time varying channel response is
a) Preset equalization
b) Adaptive equalization
c) Variable equalization
d) None of the mentioned

8. Preamble is used for
a) Detect start of transmission
b) To set automatic gain control
c) To align internal clocks
d) All of the mentioned
al.

9. The disadvantage of preset equalizer is that
a) It doesnot requires initial training pulse
b) Time varying channel degrades the performance of the system
c) All of the mentioned
d) None of the mentioned

10. For AWGN, the noise variance is
a) N0
b) N0/2
c) 2N0
d) N0/4

11. Performance of BFSK signal is ________ than BPSK.
a) 3db worse
b) 3db better
c) 6db worse
d) 6db better

12. A Gaussian distribution into the non linear envelope detector yields
a) Rayleigh distribution
b) Normal distribution
c) Poisson distribution
d) Binary distribution

13. The non coherent FSK needs ________ Eb/N0 than coherent FSK.
a) 1db more
b) 1db less
c) 3db more
d) 3db less

14. The DPSK needs ________ Eb/N0 than BPSK.
a) 1db more
b) 1db less
c) 3db more
d) 3db less

15. Coherent PSK and non coherent orthogonal FSK have a difference of ______ in PB.
a) 1db
b) 3db
c) 4db
d) 6db

16. Which is easier to implement and is preferred?
a) Coherent system
b) Non coherent system
c) Coherent & Non coherent system
d) None of the mentioned

17. Which is the main system consideration?
a) Probability of error
b) System complexity
c) Random fading channel
d) All of the mentioned
View AnswerAnswer: d

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