ECT215 Practice Test I

Instructions: There are 30 questions on this test. It is written in a style very similar to the REAL exam #1. Choose the best answer from among those given. Click the GRADE button on the bottom of the form when you want the exam graded.

Note: You can practice this test as many times as you desire; the system will cook you up a fresh batch of questions each time you access this page.

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1. When a host wants to check to see if a terminal (slave) unit on a multidrop network has anything to say, what does it do to the terminal?

a) It stops all processing and waits for the terminal to send a message.
b) It transmits a poll message with the terminal's address.
c) It continues processing; the terminal will interrupt it when ready.
d) None of the above

2. When all data bits are sent at the same time, we are sending what type of data?

a) Digital
b) Serial
c) Parallel
d) None of the above

3. Before a terminal can transmit a message on a multidrop network, what must it first do?

a) Acquire the token
b) Transmit a request to send
c) Wait for the host to send it a poll message
d) None of the above

4. When we say that a device operates full duplex, what do we mean?

a) It can only communicate in one direction.
b) It can communicate in both directions, but only one at a time.
c) It can communicate in two directions at one time.
d) None of the above

5. Which of these best describes serial data?

a) All bits are sent at the same time.
b) One bit is sent at a time.
c) The data represented in analog form.
d) None of the above

6. Which of these is best described by the term demodulation?

a) Analog to digital conversion in a modem receiver
b) Digital-to-analog conversion in a modem
c) Converting parallel data to serial data
d) None of the above

7. What is the primary disadvantage of a point-to-point (peer-to-peer) network?

a) Complicated protocol is required.
b) The security of such a network is very poor.
c) Possible high cost per unit, due to low communications line utilization.
d) None of the above

8. How many bits are encoded per transition in the figure above?

a) 1
b) 2
c) 3
d) None of the above

9. In FSK, what property of the carrier is changed in order to represent the data?

a) Amplitude
b) Phase
c) Frequency
d) None of these

10. How many bits are encoded per transition in the figure above?

a) 1
b) 2
c) 3
d) None of the above

11. What is a primary fault of single-level modulation systems?

a) They are slow and don't use bandwidth efficiently
b) They use excessive bandwidth
c) They are very sensitive to noise
d) None of the above

12. If a certain modulator produces a change in the carrier every 1 mS, what is the resulting signalling rate?

a) 500 BAUD
b) 1000 BAUD
c) 2000 BAUD
d) None of the above

13. The rate at which changes are made to an analog carrier wave is called the _______?

a) BPS
b) CPS
c) BAUD
d) None of the above

14. A system transmits data at 19.2 KBPS, and has a signalling rate of 4800 BAUD. How many bits does it encode per transition?

a) 2
b) 3
c) 4
d) None of the above

15. In a single-level modulation system, how many bits are represented for each transition?

a) 2
b) 3
c) 4
d) None of the above

16. What is meant by the terms "mark" and "space?"

a) Off and On conditions
b) Logic 1 and Logic 0 conditions
c) Ready or Not Ready conditions
d) None of these

17. A certain communication system has a bit-cell time of 1 mS and a BAUD of 500. How many bits does it encode per transition?

a) 2
b) 3
c) 4
d) None of the above

18. What two factors determine the information carrying capacity of a communications channel?

a) Bandwidth and power gain
b) S/N ratio and bandwidth
c) Power gain and S/N ratio
d) None of the above

19. A certain system has 16 modulation states and has a signalling rate of 600 BAUD. What will the resulting data rate be?

a) 1200 BPS
b) 2400 BPS
c) 4800 BPS
d) None of the above

20. A certain system has 8 modulation states and has an input data rate of 2400 BPS. What will the resulting signalling rate be?

a) 1200 BAUD
b) 2400 BAUD
c) 800 BAUD
d) None of the above

21. If light travels at 200,000,000 m/s in a material, what is its index of refraction?

a) 1.0
b) 1.5
c) 2.0
d) None of the above

22. Which of these fiber optics accepts light the easiest?

a) Acceptance cone angle = 45 degrees
b) NA = 0.707107
c) Both have an equal acceptance cone
d) Insufficient data to answer question

23. What is the speed of light in a material with an index of refraction of 2.0?

a) 150,000,000 m/s
b) 200,000,000 m/s
c) 300,000,000 m/s
d) None of these

24. Why isn't modal dispersion a problem in single-mode fiber optics?

a) Light moves through these by reflection instead of refraction
b) Single-mode fiber optics can only be used for short-length runs
c) Only one light path is possible in a single-mode fiber
d) None of these

25. What is the primary effect of dispersion in a fiber optic cable?

a) Decreases the available signal at the receiver
b) Decreases the available bandwidth
c) Sharpens the rising and falling edges of data waveforms
d) None of these

26. In the above figure, 8 data bits, 1 stop bit, and a parity bit are being sent. What type of parity is in use?

a) Odd
b) Even
c) Can't tell from information given

27. In the figure above, the parameters are 8,N,2 and the bit time is 500 uS. How many characters can be sent per second?

a) 125
b) 136
c) 181.8
d) None of the above

28. Given that the parameters are 8,N,1 above, what hex data value is being sent?

a) $F3 (0xF3)
b) $A5 (0xA5)
c) $AF (0xAF)
d) None of the above

29. In the figure above, the parameters are 8,N,1 and the bit time is 1 mS. How many characters can be sent per second?

a) 125
b) 111
c) 100
d) None of the above

30. In the above figure, 8 data bits, 1 stop bit, and a parity bit are being sent. What type of parity is in use?

a) Odd
b) Even
c) Can't tell from information given


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