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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. 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

3. The term poll means:

a) A notification of a message waiting
b) An error has been detected on a network.
c) An invitation to send
d) None of the above

4. 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

5. 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

6. 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

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. A modulator has an input data rate of 2400 BPS and encodes three bits per transition. Under these conditions, it uses up 1000 Hz of bandwidth. What will happen to the bandwidth if the data rate is reduced to 1200 BPS (and everything else stays the same)?

a) The bandwidth will remain exactly the same
b) The bandwidth will double
c) The bandwidth will become 750 Hz
d) None of the above

9. The fundamental units of digital information flow are:

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

10. 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

11. 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

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. 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

14. The data rate into a modulator is 1200 BPS, and its constellation is shown above. What will the signalling rate be?

a) 600 BAUD
b) 300 BAUD
c) 150 BAUD
d) None of these

15. 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

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. 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

18. 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

19. 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

20. 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

21. 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

22. 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

23. What type of data is sent without a clock signal?

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

24. 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

25. 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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