Chapter Questions
If the time required for the completion of one sine wave is 0.1 s , what is the frequency of the wave? If the wave's period is reduced to 0.05 s , what is its new frequency?
What information is conveyed by an unmodulated sinusoidal signal?
Why is the passband of a telephone channel 3000 Hz even though the audio spectrum heard by the human ear is approximately 20000 Hz ?
Assume the output power on a channel was measured to be one-quarter of the power input to the channel. Using the data in Table 3.1, determine the power ratio in dB .
Suppose that a signal of 22 dB is applied to a cable that has a loss of 7 dB . If an amplifier with a 12 dB gain is inserted into the cable at its opposite end, what is the output signal strength at that location?
What is the function of an amplifier?
What is the difference between thermal nolse and impulse noise? Which noise sets the lower level for receiver sensitivity?
What is the $\mathrm{S} / \mathrm{N}$ ratio? Why is a high $\mathrm{S} / \mathrm{N}$ ratio desirable but a very high $\mathrm{S} / \mathrm{N}$ ratio undesirable.
Assume the reading on a dB meter inserted into a circuit showed zero. What would this indicate. If the dB meter reading was -10 , what would this reading indicate?
What is the difference in the use of the dB and dBm ?
Why was 0 dBrn set equal to -90 dBm ?
What is the difference with respect to signal reconstruction obtained by the use of an amplifier and a digital repeater?
Discuss four causes of signal distortion on a twisted-pair cable.
Why does near end crosstalk (NEXT) diminish as the distance from the cable connector increases?
Explain the basic reason why a cable modem can operate at a data transmission rate in the millions of bits per second rate while a modem used on the switched telephone network is limited to an operating rate between 30 kbps and 56 kbps .
What is the relationship between microwave transmission and satellite communications?
What are two advantages associated with the use of transmission via optical fiber?
What is the difference between bit and baud with respect to transmission? Can they be equivalent? Can they be non-equivalent?
If the bandwidth of a channel is 100 Hz and two bits are encoded per signal change, what data transmission rate would be obtainable?
What are the core diameter and cladding diameter of a $62.5 / 125 \mu \mathrm{~m}$ fiber?
If a LAN encodes two bits into one baud and transmits at 22 Mbps can Category 4 cable be used? Explain your answer.