| 31. | A _________ sine wave is not useful in data communications; we need to send a _______ signal. |
| a. | composite; single-frequency |
| b. | single-frequency; composite |
| c. | single-frequency; double-frequency |
| d. | none of the above |
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Answer: (b).single-frequency; composite
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| 32. | The _____ of a composite signal is the difference between the highest and the lowest frequencies contained in that signal. |
| a. | frequency |
| b. | period |
| c. | bandwidth |
| d. | amplitude |
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Answer: (c).bandwidth
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| 33. | A(n)_________ signal is a composite analog signal with an infinite bandwidth. |
| a. | digital |
| b. | analog |
| c. | either (a) or (b) |
| d. | neither (a) nor (b) |
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Answer: (a).digital
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| 34. | Baseband transmission of a digital signal is possible only if we have a ____ channel. |
| a. | low-pass |
| b. | bandpass |
| c. | low rate |
| d. | high rate |
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Answer: (a).low-pass
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| 35. | If the available channel is a ____ channel, we cannot send a digital signal directly to the channel. |
| a. | low-pass |
| b. | bandpass |
| c. | low rate |
| d. | high rate |
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Answer: (b).bandpass
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| 36. | For a ______ channel, the Nyquist bit rate formula defines the theoretical maximum bit rate. |
| a. | noisy |
| b. | noiseless |
| c. | bandpass |
| d. | low-pass |
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Answer: (b).noiseless
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| 37. | For a ______ channel, we need to use the Shannon capacity to find the maximum bit rate. |
| a. | noisy |
| b. | noiseless |
| c. | bandpass |
| d. | low-pass |
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Answer: (a).noisy
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| 38. | _________ can impair a signal. |
| a. | Attenuation |
| b. | Distortion |
| c. | Noise |
| d. | All of the above |
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Answer: (d).All of the above
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| 39. | The _________ product defines the number of bits that can fill the link. |
| a. | bandwidth-period |
| b. | frequency-amplitude |
| c. | bandwidth-delay |
| d. | delay-amplitude |
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Answer: (c).bandwidth-delay
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| 40. | The portion of physical layer that interfaces with the media access control sublayer is called |
| a. | physical signalling sublayer |
| b. | physical data sublayer |
| c. | physical address sublayer |
| d. | none of the mentioned |
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Answer: (a).physical signalling sublayer
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