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
View Answer
Explanation: When pulse modulation is applied to binary symbol we obtain pulse code modulated waveforms. These waveforms are also called as line codes.
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
View Answer
Explanation: When pulse code modulation is applied to binary symbols we get PCM waveforms and when it is applied to non binary symbols we obtain M-ary waveforms.
3. Examples of PCM waveforms are
a) Non return to zero
b) Phase encoded
c) Multilevel binary
d) All of the mentioned
View Answer
Explanation: Some of the examples or classification of pulse code modulated signals are non return to zero, return to zero, phase encoded, multilevel binary etc.
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
View Answer
Explanation: NRZ-L is extensively used in digital logic circuits. In this method, logic 1 is represented by one voltage level and logic 0 is represented by another voltage level.
5. Which method is called as differential encoding?
a) NRZ-L
b) NRZ-M
c) NRZ-S
d) None of the mentioned
View Answer
Explanation: In NRZ-M, logic 1 is represented by a change in voltage level and logic 0 is represented by no change in level. This is called as differential encoding.
6. Which method is preferred in magnetic tape recording?
a) NRZ-L
b) NRZ-M
c) NRZ-S
d) None of the mentioned
View Answer
Explanation: NRZ-M is also called as differential encoding and it is most preferred in magentic tape recording.
7. NRZ-S is complement of _______
a) NRZ-L
b) NRZ-M
c) NRZ-L & NRZ-M
d) None of the mentioned
View Answer
Explanation: NRZ-S is a complement of NRZ-M. Logic 0 is represented by a change in voltage level and logic 1 is represented as no change in voltage level.
8. The return to zero waveform consists of
a) Unipolar RZ
b) Bipolar RZ
c) RZ-AMI
d) All of the mentioned
View Answer
Explanation: Different types of return to zero waveforms are unipolar RZ, bipolar RZ, RZ-AMI. These are used in baseband transmission and in magnetic recording.
9. Phase encoded group consists of
a) Manchester coding
b) Bi-phase-mark
c) Miller coding
d) All of the mentioned
View Answer
Explanation: Different types of phase encoded waveform consists of manchester coding, bi-phase-mark, bi-phase-space, delay modulation.
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
View Answer
Explanation: In unipolar RZ waveform, logic 1 is represented by half bit wide pulse and logic 0 is represented by the absence of a pulse.
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
View Answer
Explanation: In bipolar return to zero waveform ones and zeroes are represented by opposite level pulses one half bit wide pulses.
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
View Answer
Explanation: In RZ-AMI logic 1 is represented by equal amplitude alternating pulses and logic 0 is represented by the absence of a pulse.
Sanfoundry Global Education & Learning Series – Digital Communications.
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