Digital Communications 1-66

1. Which of the following term best described the overload distortion?

• A. Peak limiting
• B. Quantization noise
• C. Granular noise
• D. Slope distortion

2. The advantage(s) of digital and/or data communications over analog include

• A. Noise performance
• B. Regeneration
• C. Digital signal processing
• D. All the above

3.. Data communications refer to the transmission of

• A. Voice
• B. Video
• C. Computer data
• D. All of the above

4. Hartley’s Law is:

• A. I = ktB
• B. C = 2Blog2M
• c. C = Blog2(1+S/N)
• D. SR = 2fmax

5. Most LANS:

• A. are based on Ethernet
• B. use CSMA/CD
• C. use UTP cable
• D. All of the above

6. In the equation C = 2Blog2M, M is the:

• A. margin of noise
• B. modulation index
• C. number of possible states per symbol
• D. maximum number of symbols per second

7. In a digital system, the transceiver is connected to the

• A. modem
• B. computer
• C. scanner
• D. input/output

8. Guard bands increase the bandwidth for

• A. FDM
• B. TDM pado
• C. Both (a) and (b)
• D. None of the above

9. What is the efficiency of 8B/10B encoding?

• A. 20 percent
• B. 40 percent
• C. 60 percent
• D. 80 percent

10. If a host needs to synchronize its clock with another host, it sends a message.

• A. Time-stamp request
• B. Source-quench
• C. Routert-advertisement
• D. Time-exceeded