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1. Before a unit can transmit a message on a ring network, what must it first do?

a) Transmit a request to send
b) Acquire the token
c) Wait for permission from the host
d) None of the above

2. 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

3. 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

4. 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

5. What is one disadvantage of serial data over parallel data?

a) The hardware to generate serial data is very expensive.
b) Serial data is much more prone to transmission errors than parallel.
c) The transmission speed of serial data is slower.
d) None of these

6. A ______ system can only communicate in one direction. (Fill in the blank.)

a) Simplex
b) Half-duplex
c) Full-duplex
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. 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

9. Which modulation method below changes the frequency of the carrier in order to represent the data?

a) FSK
b) ASK
c) PSK
d) None of these

10. The fundamental units of digital information flow are:

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

11. 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

12. Which of the below factors limits the number of bits per transition in practical communication systems?

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

13. If the signalling rate is 600 BAUD and the constellation is as shown above, what will the actual data rate be?

a) 4800 BPS
b) 2400 BPS
c) 1200 BPS
d) None of these

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. 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

16. 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

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

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

19. 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

20. Which of these is a method of impressing information onto a carrier wave?

a) Amplitude modulation (AM)
b) Frequency modulation (FM)
c) Phase modulation (PM)
d) All of the above
e) None of the above

21. What mechanism keeps light inside of a fiber optic cable?

a) Refraction
b) Diffraction
c) Reflection
d) None of the above

22. What is the meaning of the term 'numerical aperture'?

a) Ease of getting light into the fiber
b) Decibel loss per unit length in the fiber
c) Ease of splicing the fiber
d) None of the above

23. 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

24. 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

25. 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

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,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

28. When a clock is sent with data, it is called ______ data.

a) Asynchronous
b) Synchronous
c) Digital
d) None of the above

29. 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

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

a) $AB (0xAB)
b) $D3 (0xD3)
c) $D5 (0xD5)
d) None of the above

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