# Practice Quiz in Digital and Data Communication Networks Part 3

Online Practice Quiz in Digital and Data Communication Networks part 3 as one of the Communications Engineering topic.

This is the Online Practice Quiz in Digital and Data Communication Networks Part 3 as one of the Communications Engineering topic. In Preparation for the ECE Board Exam make sure to expose yourself and familiarize in each and every questions compiled here taken from various sources including but not limited to past Board Examination Questions in Electronic System and Technologies, Communications Books, Journals and other Communications References.

### Continue Part III of the Online Practice Quiz

#### Quiz in Digital and Data Communication Networks

Question 21. Determine the channel capacity of a 4 kHz channel with S/N = 10 dB.

A. 8.02 kbps

B. 4.17 kbps

C. 13.74 kbps

D. 26.58 kbps

Question 22. If the transmission rate of a digital communication system of 10 Mbps modulation scheme used in 16-QAM, determined the bandwidth efficiency.

A. 16 bits/cycle

B. 4 bits/cycle

C. 8 bits/cycle

D. 2 bits/cycle

Question 23. AM and FM are examples of ________ encoding.

A. Digital-to-digital

B. Digital-to-analog

C. Analog-to –analog

D. Analog-to-digital

Question 24. If the maximum value of a PCM signal is 31 and the minimum value is -31, how many bits were used for coding?

A. 4

B. 5

C. 6

D. 7

Question 25. A maximum length of 50 feet is specified in standard __________.

A. EIA-RS-449

B. EIA-RS-232

C. EIA-RS-423

D. RS-422

Question 26. ASK, PSK, FSK, and QAM are examples of _________ encoding.

A. Digital-to-digital

B. Digital-to-analog

C. Analog-to –analog

D. Analog-to-digital

Question 27. X-21 uses a _____ connector.

A. DB-15

B. DB-25

C. DB37

D. DB-9

Question 28. For digital communications, determine the signal to noise ratio in dB which would be required for an ideal channel with a bandwidth of 2500 Hz.

A. 5 dB

B. 9.54 dB

C. 4.77 dB

D. 3.4 db

Question 29. Which ITU-T modem uses trellis coding?

A. V.33

B. V.34

C. V.39

D. V.37

Question 30. A binary digital signal is to be transmitted at 10 Kbits/s, what absolute minimum bandwidth is required to pass the fastest information change undistorted?

A. 5 kHz

B. 10 kHz

C. 20 kHz

D. 2.5 kHz

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