 # Communications Engineering Mastery Test 15: ECE Pre-Board

(Last Updated On: January 1, 2018) This is 100 items Practice Examinations set 15 in Communications Engineering (Electronics Systems and Technology) composed of previous Board Exams Questions. Read each questions and choices carefully! Choose the best answer. In the actual board, you have to answer 100 items in Communications Engineering within 5 hours. You have to get at least 70% to pass the subject. Communications Engineering is 30% of the total 100% Board Rating along with Mathematics (20%), General Engineering and Applied Sciences (20%) and Electronics Engineering (30%). Familiarize each and every questions to increase the chance of passing the ECE Board Examination.

### Start the Test Yourself Exam 15

Choose the letter of the best answer in each questions.

1. Technique employed by wireless infrastructure systems that lowers the power of a signal in a cell site whenever the site detects that the user’s phone is close to the source of the signal

• B. Pre-emphasis
• C. Level down
• D. Power attenuation

Solution:

2. A relative range of frequencies that can carry a signal without distortion on a transmission medium

• A. Doppler frequency
• B. Carrier
• C. Bandwidth or pipe
• D. Channel

Solution:

3. Suppose a TV signal has 10.5 microseconds of horizontal blanking per line and 21 lines of vertical blanking per field. What is the percentage of total time that is occupied by blanking?

• A. 22.92%
• B. 93.22%
• C. 11.45%
• D. 16.67%

Solution:

4. Estimate the bandwidth occupied by the sound portion of a TV transmission in US.

• A. 25 kHz
• B. 800 kHz
• C. 80 kHz
• D. 200 kHz

Solution:

5. What is the purpose of using alternate mark inversion and return to zero encoding of data?

• A. faster digital data transmission
• B. assist in clock recovery
• C. more efficient transmission of analog data
• D. reduced susceptibility to noise

Solution:

6. A measure of the number of subscribers who leave or switch to another carrier’s service

• A. Offered traffic
• B. Churn
• C. Carried traffic
• D. Population

Solution:

7. The power amplifier of an AM transmitter has an output power of 50 W and an efficiency of 60% and is collector modulated. How much audio power is required to be supplied to this stage for 100% modulation?

• A. 833 W
• B. 41.66 W
• C. 30 W
• D. 15 W

Solution:

8. The old standard unit for measuring the activity of a given radioactive sample which is equivalent to the activity of 1 gram of radium.

• A. Curie
• B. Becquerel
• D. Rem

Solution:

9. A combination of two or more integrated circuits on one module

• A. PCB
• B. Combo chip
• C. TTL
• D. Chip set

Solution:

10. The term applied to a phone that will work on 800 MHz analog, 800 MHz digital and 1900 MHz (also known as 1.9 GHz) frequencies

• A. Tri-mode
• B. Tri Band
• C. Dual Band
• D. Dual-mode

Solution:

11. A pen-based tablet computer used on a wireless local area network

• A. node
• B. source
• C. thin client
• D. master

Solution:

12. 1 Petabits is equivalent to how many bits of digital information?

• A. 1 x 1015 bits
• B. 1, 073, 741, 824 bits
• C. 1, 099, 511, 627, 776 bits
• D. 1, 125, 899, 906, 842, 624 bits

Solution:

13. Where is de-emphasis added in a stereo FM system?

• A. before the matrix at the TX
• B. before the matrix at the R
• C. after the matrix at the TX
• D. after the matrix at the RX

Solution:

14. How many electron beams actually leave the electron gun of a single-gun color CRT?

• A. 1
• B. 2
• C. 3
• D. 4

Solution:

15. Determine the quality factor necessary for a single sideband filter with a 1-MHz carrier frequency, 80 dB unwanted suppression and 200-Hz frequency separation.

• A. 15,000
• B. 125,000
• C. 12,000
• D. 25,000

Solution:

16. A rectangular waveguide has a width of 0.6 inch. Calculate the waveguide cut-off frequency.

• A. 12.84 GHz
• B. 5.84 GHz
• C. 10.84 GHz
• D. 9.84 GHz

Solution:

17. A permanent-magnet ring on the neck of the tube is used for ________.

• A. scanning
• B. centering
• C. deflecting
• D. focusing

Solution:

18. The IS-95 CDMA standard developed by Qualcomm Inc

• A. WCDMA
• B. IMT-DS
• C. cdmaOne
• D. IMT-SC

Solution:

19. The process of creating more coverage and capacity in a geographic area by having more than one cell cover the same area that a single cell originally did

• A. Cell splitting
• B. Frequency reuse
• C. Cell reuse
• D. Cell site

Solution:

20. Gregorian antenna is consist of

• A. Main paraboloid reflector and an ellipsoid subreflector
• B. Main paraboloid reflector and a hyperboloid subreflector
• C. Main ellipsoid reflector and a hyperboloid subreflector
• D. Main hyperboloid reflector and an ellipsoid subreflector

Solution:

21. A logic channel carrying network information rather than the actual voice or data messages transmitted over the network

• A. Control channel
• B. Backup channel
• D. Message channel

Solution:

22. In which ITU region is Philippines?

• A. ITU Region 1
• B. ITU Region 2
• C. ITU Region 3
• D. ITU Region 4

Solution:

23. What is the result of over deviation in an FM transmitter?

• A. Increased transmitter range
• B. Increased transmitter power
• C. Poor carrier suppression
• D. Out-of-channel emissions

Solution:

24. What is the output PEP from a transmitter if an oscilloscope measures 500 volts peak-to-peak across a 50-ohm resistor connected to the transmitter output?

• A. 500 watts
• B. 625 watts
• C. 1250 watts
• D. 2500 watts

Solution:

25. _________ is the process of impressing or imparting a low frequency source information (voice, audio, video, or data) onto a high-frequency bandpass signal with a carrier frequency fc by the introduction of amplitude, frequency or phase perturbation.

• A. Mixing
• B. Modulation
• C. Heterodyning
• D. Multiplexing 