Pseudo Noise Sequence

Digital Communications Systems
This set of Digital Communications Multiple Choice Questions & Answers (MCQs) focuses on “Pseudo-noise sequence and jamming”.
1. Pseudorandom signal ________ predicted.
a) Can be
b) Cannot be
c) maybe
d) None of the mentioned

2. The properties used for pseudorandom sequence are
a) Balance
b) Run
c) Correlation
d) All of the mentioned

3. The shift register needs to be controlled by clock pulses.
a) True
b) False

4. A linear feedback shift register consists of
a) Feedback path
b) Modulo 2 adder
c) Four stage register
d) All of the mentioned

5. If the initial pulse of 1000 is fed to shift register, after how many clock pulses does the sequence repeat?
a) 15
b) 16
c) 14
d) 17

6. The sequences produced by shift register depends on
a) Number of stages
b) Feedback tap connections
c) Initial conditions
d) All of the mentioned


7. For maximal length sequence, the sequence repetition clock pulses p is given by
a) 2n + 1
b) 2n -1
c) 2n
d) None of the mentioned

8. For any cyclic shift, the auto-correlation function is equal to
a) 1/p
b) -1/p
c) –p
d) p

9. Which method is better?
a) To share same bandwidth
b) To share different bandwidth
c) To share same & different bandwidth
d) None of the mentioned

10. Pulse jammer consists of
a) Pulse modulated excess band noise
b) Pulse modulated band-limited noise
c) Pulse width modulated excess band noise
d) Pulse width modulated band-limited noise

11. Which are the design options for anti jam communicator?
a) Time diversity
b) Frequency diversity
c) Special discrimination
d) All of the mentioned

12. The ratio (J/S)reqd gives the measure of
a) Vulnerability to interference
b) Invulnerability to interference
c) All of the mentioned
d) None of the mentioned

13. The system should have
a) Larger (J/S)reqd
b) Greater system’s noise rejection capability
c) Larger (J/S)reqd & Greater system’s noise rejection capability
d) None of the mentioned

14. The broadband jammer jams the entire
a) W
b) Wss
c) W & Wss
d) None of the mentioned

15. To increase error probability, the processing gain should be
a) Increased
b) Decreased
c) Exponentially increased
d) Exponentially decreased

16. Which jamming method produces greater degradation?
a) Broadband jamming
b) Partial jamming
c) Broadband & Partial jamming
d) None of the mentioned

17. The jammer which monitors a communicator’s signal is known as
a) Frequency follower jammers
b) Repeat back jammers
c) Frequency follower & Repeat back jammers
d) None of the mentioned

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