Final Exam

Question 1

Line-Coding: Unipolar Scheme?

Answer 1

Positive voltage = bit 1.

Zero voltage = bit 0.

Question 2

Line-Coding: NRZ-Levels?

Answer 2

A polar scheme.

Positive voltage = bit 0.
Negative voltage = bit 1.

Question 3

Line-Coding: NRZ-Invert?

Answer 3

A polar scheme.

If next bit is 1, the voltage inverts; if the next bit is 0, the voltage stays the same.

Question 4

What are Return-to-Zero (RZ) Schemes?

Answer 4

Positive, negative, zero voltage.

Signal always goes to zero in the MIDDLE of the bit.

Question 5

Line-Coding: Biphase Manchester?

Answer 5

A RZ Scheme that combines RZ and NRZ-Levels.

If bit is 1, voltage always returns to positive voltage in middle of bit. If bit is 0, voltage returns to negative voltage in middle of bit.

Question 6

Line-Coding: Differential Manchester?

Answer 6

A RZ Scheme that combines RZ and NRZ-Invert.

If next bit is 0, there’s a transition; if next bit is 1, there is NO transition.

Question 7

A-to-A Conversion: Frequency Modulation (FM)

Answer 7

Positive amp = high freq.

Negative amp = low freq.

Question 8

A-to-A Conversion: Phase Modulation (PM)

Answer 8

Greater slope = high freq.

Flatter slope = low freq.

Question 9

A-to-A Conversion: Amplitude Modulation (AM)