This set of Digital Communications Multiple Choice Questions & Answers (MCQs) focuses on “Baseband transmission – 1”.
1. Which waveforms are also called as line codes?
a) PCM
b) PAM
c) FM
d) AM
2. When pulse code modulation is applied to non binary symbols we obtain waveform called as
a) PCM
b) PAM
c) M-ary
d) line codes
3. Examples of PCM waveforms are
a) Non return to zero
b) Phase encoded
c) Multilevel binary
d) All of the mentioned
4. Which type is used and preferred in digital logic circuits?
a) NRZ-L
b) NRZ-M
c) NRZ-S
d) None of the mentioned
5. Which method is called as differential encoding?
a) NRZ-L
b) NRZ-M
c) NRZ-S
d) None of the mentioned
6. Which method is preferred in magnetic tape recording?
a) NRZ-L
b) NRZ-M
c) NRZ-S
d) None of the mentioned
7. NRZ-S is complement of _______
a) NRZ-L
b) NRZ-M
c) NRZ-L & NRZ-M
d) None of the mentioned
8. The return to zero waveform consists of
a) Unipolar RZ
b) Bipolar RZ
c) RZ-AMI
d) All of the mentioned
9. Phase encoded group consists of
a) Manchester coding
b) Bi-phase-mark
c) Miller coding
d) All of the mentioned
10. In which waveform logic 1 is represented by half bit wide pulse and logic 0 is represented by absence of pulse?
a) Unipolar RZ
b) Bipolar RZ
c) RZ-AMI
d) Manchester coding
11. In which waveform logic 1 and logic 0 are represented by opposite one half bit wide pulses?
a) Unipolar RZ
b) Bipolar RZ
c) RZ-AMI
d) Manchester coding
12. In which waveform logic 1 is represented by equal amplitude alternating pulses?
a) Unipolar RZ
b) Bipolar RZ
c) RZ-AMI
d) Manchester coding
13. Application of phase encoded binary signals are
a) Optical communication
b) Magnetic recording
c) Satellite telemetry
d) All of the mentioned
14. In which waveform one is represented by half bit wide pulse positioned during the first half and zero is represented by half bit wide pulse positioned in the second half?
a) Bi-p-L
b) Bi-p-M
c) Bi-p-S
d) Delay modulation
15. Which binary waveform uses three levels?
a) Bipolar RZ
b) RZ-AMI
c) Bipolar RZ & RZ-AMI
d) None of the mentioned
16. Which waveform type has the feature of clocking?
a) Manchester coding
b) Bbi-p-M
c) Delay modulation
d) NRZ-L
17. Which waveform has the feature of error detection?
a) NRZ-L
b) RZ-AMI
c) Manchester coding
d) Duobinary
18. Which waveform scheme introduces bandwidth compression?
a) Duobinary
b) Manchester coding
c) Phase encoded waveform
d) Multilevel codes
19. Which waveform type has better noise immunity?
a) NRZ
b) RZ
c) Phase encoded
d) Multilevel codes
20. In pulse modulation, reciprocal of T(time) is
a) Bandwidth
b) Symbol rate
c) Signal voltage
d) None of the mentioned
21. PCM word size can be described by
a) Time period
b) Symbol rate
c) Number of quantization levels
d) None of the mentioned
22. Some of the M-ary waveforms are
a) PAM
b) PPM
c) PDM
d) All of the mentioned
23. Which method should be implemented for reducing bandwidth?
a) Multilevel codes
b) Multilevel signalling
c) PAM
d) PDM
24. In M-ary PPM waveform, modulation is effected by
a) Delaying
b) Advancing
c) Delaying & Advancing
d) None of the mentioned
25. For both PPM and PDM _______ is kept constant.
a) Amplitude
b) Time period
c) Frequency
d) Number of levels