1. When are two wireless signals said to be in phase?
- when two identical signals are produced and one signal is slightly delayed from the other
- when two identical signals are produced exactly at the same time and their cycles vary slightly
- when two identical signals are produced exactly at the same time and their cycles match up
- when two different signals are produced and one signal is slightly delayed from the other
2. What two IEEE 802.11 wireless standards operate only in the 5 GHz range? (Choose two.)
- 802.11a
- 802.11b
- 802.11g
- 802.11n
- 802.11ac
- 802.11ad
3. A wireless engineer is comparing wireless survey scans from the previous network engineer and finds a report of RSSI values. Which RSSI value indicates the strongest signal power level?
- 0
- 1
- 255
- 256
4. Which MIMO device supports three spatial streams with two receivers and three transmitters?
- 3×3:3 device
- 3×2:3 device
- 2×3:3 device
- 2×3:2 device
5. How is a wavelength commonly described as the signal moves through free space?
- A wavelength is the measure of the number of times the signal makes one complete up and down cycle in a single second.
- A wavelength is the measure of shift in time relative to the start of a cycle.
- A wavelength is the measure of the physical distance that a wave travels over one complete cycle.
- A wavelength is the measure of the complete RF signal as it spills above and below a center frequency.
6. How is the frequency of a wave measured?
- the number of seconds the signal takes to complete one up and down cycle
- the number of times the signal makes one complete up and down cycle in 1 second
- the number of times the signal makes one complete up and down cycle in 2 seconds
- the number of seconds the signal takes to complete two up and down cycles
7. How will a wireless device use dynamic rate shifting to maintain data integrity as a mobile user moves farther and farther away from the wireless transmitter?
- The wireless device will use a lower data rate.
- The wireless device will use an increased data rate.
- The wireless device will use maximal-ratio combining.
- The wireless device will use transmit beamforming.
8. Which three attributes can be altered to indicate that information is being carried over an RF signal? (Choose three.)
- channel width
- frequency
- amplitude
- phase
- channel spacing
- wave propagation
9. Refer to the exhibit. It displays the sources of A, B, and C and the corresponding absolute power of each. In comparing source A and B, how much greater is the signal strength of source B than the strength of A?
- 3 dB
- 4 dB
- 6 dB
- 30 dB
10. How is the strength or amplitude of an RF signal measured?
- It is measured by the height from the top peak to the bottom peak of the waveform of a signal.
- It is measured by the number of times the signal makes one complete up and down cycle in a single second.
- It is measured from the center of one peak to the center of the next peak.
- It is measured by the physical distance that a wave travels over one complete cycle.
11. How can an 802.11ac wireless device use transmit beamforming to more efficiently reach a client location?
- The same signal can be provided to each transmitting antenna with a slight alteration to the phase of the signal so that the resulting signals will all arrive out of phase at the receiver.
- The same signal can be provided to each transmitting antenna with a slight alteration to the phase of the signal so that the resulting signals will all arrive in phase at the receiver.
- A different signal can be provided to each transmitting antenna with a slight alteration to the phase of the signal so that the resulting signals will all arrive in phase at the receiver.
- A diferent signal can be provided to each transmitting antenna with a slight alteration to the phase of the signal so that the resulting signals will all arrive out of phase at the receiver.
12. A wireless engineer is deploying wireless network devices and client devices that support both 2.4 GHz and 5 GHz transmitters. Which concern should the wireless engineer consider in the deployment of this technology?
- The 5 GHz band will suffer from a greater free space path loss than the 2.4 GHz band.
- The 2.4 GHz band will require additional EIRP to match the range of the 5 GHz band.
- The 2.4 GHz band will suffer from a greater free space path loss than the 5 GHz band.
- The 5 GHz band will suffer from free space path loss only while transmitting a signal roughly 3 meters or further from an antenna.
“Do I Know This Already?” Quiz Answers:
1. Two transmitters are each operating with a transmit power level of 100 mW. When you compare the two absolute power levels, what is the difference in dB?
- 0 dB
- 20 dB
- 100 dB
- You can’t compare power levels in dB.
2. A transmitter is configured to use a power level of 17 mW. One day it is reconfigured to transmit at a new power level of 34 mW. How much has the power level increased, in dB?
- 0 dB
- 2 dB
- 3 dB
- 17 dB
- None of these answers are correct; you need a calculator to figure this out.
3. Transmitter A has a power level of 1 mW, and transmitter B is 100 mW. Compare transmitter B to A using dB, and then identify the correct answer from the following choices.
- 0 dB
- 1 dB
- 10 dB
- 20 dB
- 100 dB
4. A transmitter normally uses an absolute power level of 100 mW. Through the course of needed changes, its power level is reduced to 40 mW. What is the power-level change in dB?
- 2.5 dB
- 4 dB
- −4 dB
- −40 dB
- None of these answers are correct; where is that calculator?
5. Consider a scenario with a transmitter and a receiver that are separated by some distance. The transmitter uses an absolute power level of 20 dBm. A cable connects the transmitter to its antenna. The receiver also has a cable connecting it to its antenna. Each cable has a loss of 2 dB. The transmitting and receiving antennas each have a gain of 5 dBi. What is the resulting EIRP?
- +20 dBm
- +23 dBm
- +26 dBm
- +34 dBm
- None of these answers are correct.
6. A receiver picks up an RF signal from a distant transmitter. Which one of the following represents the best signal quality received? Example values are given in parentheses.
- Low SNR (10 dB), low RSSI (−75 dBm)
- High SNR (30 dB), low RSSI (−75 dBm)
- Low SNR (10 dB), high RSSI (−55 dBm)
- High SNR (30 dB), high RSSI (−55 dBm)
7. Which one of the following is the primary cause of free space path loss?
- Spreading
- Absorption
- Humidity levels
- Magnetic field decay
8. Which one of the following has the shortest effective range in free space, assuming that the same transmit power level is used for each?
- An 802.11g device
- An 802.11a device
- An 802.11b device
- None of these answers
9. QAM alters which of the following aspects of an RF signal? (Choose two.)
- Frequency
- Amplitude
- Phase
- Quadrature
10. Suppose that an 802.11a device moves away from a transmitter. As the signal strength decreases, which one of the following might the device or the transmitter do to improve the signal quality along the way?
- Aggregate more channels
- Use more radio chains
- Switch to a more complex modulation scheme
- Switch to a less complex modulation scheme