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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
Answer: (b).single-frequency; composite

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
Answer: (c).bandwidth

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)
Answer: (a).digital

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
Answer: (a).low-pass

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
Answer: (b).bandpass

36. For a ______ channel, the Nyquist bit rate formula defines the theoretical maximum bit rate.
a. noisy
b. noiseless
c. bandpass
d. low-pass
Answer: (b).noiseless

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
Answer: (a).noisy

38. _________ can impair a signal.
a. Attenuation
b. Distortion
c. Noise
d. All of the above
Answer: (d).All of the above

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
Answer: (c).bandwidth-delay

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
Answer: (a).physical signalling sublayer

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