Communications Quiz

1. Electronic communications was discovered in which century?
sixteenth
eighteenth
nineteenth
twentieth

2. What is the standard for wireless technology known as Bluetooth?
IEEE 802.15
IEEE 802.11b
IEEE 802.11a
IEEE 802.20

3. When the first symbol in the FCC signal classification is J, it means:
having an amplitude modulated single sideband suppressed carrier
having a frequency modulated main carrier
having an unmodulated main carrier
having an amplitude modulated single sideband full carrier

4. The ratio of the peak modulating signal voltage to the peak carrier voltage is referred to as:
modulation index
modulation coefficient
both a or b
neither a or b

5. ASCII code has how many bits?
4
7
5
8

6. The IEEE standard use for high speed wireless Ethernet access known as Wi-Fi is
803.12
803.11b
802.11b
802.11

7. What is the first symbol of a radio signal emission having an amplitude modulated main carrier, double sideband?
C
H
B
A

8. All electronic components except one below generate noise:
resistor
capacitor
transistor
diode

9. What is the reference temperature used in noise analysis?
75-K
290-K
250-K
300-K

10. The solar cycle repeats the period of great electrical disturbance approximately every:
11 years
9 years
10 years
8 years

11. For ideal AM, which of the following is true?
m = 0
m = 1
m < 1
m > 1

12. The outline of the peaks of a carrier has a shape of the modulating signal is called:
trace
waveshape
envelope
carrier variation

13. Overmodulation occurs when
Vm > Vc
Vm < Vc
Vm = Vc
Vm = Vc = 0

14. The value of Vmax and Vmin as read from an oscilloscope are 2.8 and 0.3 respectively. The percent of modulation is
10.7
41.4
80.6
93.3

15. A carrier of 880-kHz is modulated by a 3.5-kHz sine wave. The LSB and USB are ___ and ___ respectively.
873- and 887-kHz
876.5- and 883.5-kHz
883.5- and 876.5-kHz
887- and 873-kHz

16. For 100% modulation, what percentage power is in each sideband?
25%
33.33%
50%
100%

17. In an AM signal, the transmitted information is contained within the
carrier
modulating signal
sideband
envelope

18. Amplitude modulation can be produced by
having the carrier vary in amplitude
having the modulating signal vary in amplitude
having the carrier vary in frequency
having the modulating signal vary in frequency

19. Noise is primarily
high frequency spikes
low frequency spikes
random level shifts
random frequency variations

20. The noise voltage across the 300-ohm input resistance to a TV set with 6-MHz bandwidth and an ambient temperature is:
2.3-mV
3.8-uV
5.4-uV
6.4-nV

21. A transmitter radiates a total power of 10-kW. The carrier is modulated to a depth of 60%. Calculate the power in the carrier and each sideband.
687- and 345-W
856- and 876-W
788- and 894-W
847- and 762-W

22. Noise at the input to a receiver can be as high as several
uV
mV
nV
V

23. Which of the following is not a source of external noise?
thermal agitation
audio ignition
sun
fluorescent light

24. Noise can be reduced by:
widening the bandwidth
narrowing the bandwidth
increasing the temperature
increasing the resistance level

25. An AM signal with a maximum modulating frequency of 4.5-kHz has a total bandwidth of
4.5-kHz
6.75-kHz
9-kHz
18-kHz