1. Find the factor which is NOT accounted for by today’s modern communication sy
ID: 2083030 • Letter: 1
Question
1. Find the factor which is NOT accounted for by today’s modern communication systems.
a) Format of the information
b) Transmission speed
c) Modulation technique
d) Transmission noise and loss
2. What is the device which superimposes information onto a high-frequency signal for
transmission?
a) Demodulator
b) The carrier
c) Transmitter
d) Modulator
4. If system has a voltage gain of 25 dB, find the applied voltage if the output voltage is 5.2V.
a) 292.4 mV b) 341.9 mV c) 382.5 mV d) 452.7 mV
5. Find the advantage which is NOT associated with using the system analysis.
a) Reduced size
b) Reduced construction time and cost
c) Reduced number of port models of system
d) Sophisticated and tested design
6. Which class of switching exchange is used to interconnect the regional centers?
a) Class 1
b) Class 2
c) Class 3
d) Class 4
7. Which of the following function is NOT accounted to BORSCHT functions?
a) Battery Feed with Loop Current Limiting
b) Hybrid
c) Regulate the speech amplitude
d) Supervision/Signaling
What makes conductors of a transmission line behave differently at high frequencies than they do at
low frequencies?
a) At high frequencies, there are many sources of line loss.
b) At high frequencies, signal sent down a wire may be reflected back.
c) At high frequencies, there are inductive, capacitive, and resistive effects to transmission lines.
d) All of the above.
9. What is the ringing signal voltage of the telephone service?
a) 90 Vrms at 20 Hz
b) – 48 V DC
c) 90 Vrms at 50 Hz
d) 127 Vrms at 20 Hz
10. A commonly used coaxial cable, RG-8A/U, has a capacitance of 29.5 pF/ft and inductance of 73.75
nH/ft. Determine its characteristics impedance (Z0) for 1-ft section.
a) 50 b)75 c)100 d)150
11. Which of the following equipment is NOT associated with electrically powered equipment of active
optical network in order to distribute the optical signal?
a) Beam splitter b) Switch c) Router d) Multiplexer
12. Which of the following is NOT an advantage that VoIP has over traditional network?
a) VoIP can integrate with other services available over the Internet
b) VoIP is location independent
c) VoIP can integrate into global telephone number system
d) VoIP has a simple way to add an extra telephone line to a home or office
13. Which switching system in central office uses the most advanced computerizes switching protocol?
a) Step by step switching
b) Crossbar switching
c) Electromechanical switching
d) Electronic switching system
14. Since the Erlang is used in telephony as a statistical measure of the volume of telecommunications
traffic, what Erlang may be regarded if total cell phone use in a given area per hour is 180 minutes?
a) 1 Erlang b) 2 Erlang c) 3 Erlang d) 4 Erlang
Compute the absolute power gain, Ap(dBm), associated with 2.5 W signal.
a) 13.25 dBm
b) 25.37 dBm
c) 33.98 dBm
d) 45.87 dBm
17. An rf sine-wave generator whose output impedance is 50 is connected to a 50- load using 50-
coaxial cable. The generator’s output amplitude level is set to +10 dBm. An rms voltmeter is
used to measure the effective voltage, and an oscilloscope is used to display the sine wave.
Compute the rms voltage measured by the rms voltmeter.
a) 404 mV
b) 505 mV
c) 606 mV
d) 707 mV
In conductor at high frequencies, most of the current flow is at the outer surface of the conductor,
This phenomena is known as;
a) radiation loss
b) the skin effect
c) surface loss
d) resistive attenuation
20. Which of the following is NOT an advantage that microwave radio links has over coaxial media?
a) Fewer repeaters are necessary for amplifying signals
b) Underground facilities are not necessary
c) Multiple channels can be transmitted over a single link
d) High propagation velocity rating can be obtained with excellent phase delay response
21. Evaluate X + Y and assume that the complex numbers are X = 2ej/3 and Y = 5ej/4.
a) 3.35 + j6.55
b) 3.35 – j6.55
c) 4.54 + j5.27
d) 4.54 – j5.27
25. When a satellite is parked in orbit approximately 22,300 miles of the earth’s surface, what is the
name of orbit?
a) Geosynchronous orbit
b) Low polar Earth orbit
c) Molniya orbit
d) Lunar orbit
26. Which of DSL services that provides 1.544 Mbps form the user to the service provider and up to 8
Mbps back to the user from the service provider?
a) IDSL b) VDSL c)HDSL d)ADSL
27. Which multiplexing technology multiplexes multiple optical carrier signals on a single optical fiber?
a) Space division multiplexing
b) Frequency division multiplexing
c) Time division multiplexing
d) Wavelength division multiplexing
28. Determine the probability of blocking (B) by applying the Erlang B formula where the number of
resources (N) is 4 and the total amount of traffic offered in Erlangs (A) is 2.
a) 0.035 b)0.055 c)0.075 d)0.095
A citizen’s band transmitter operating at 27 MHz with 4-W output is connected via 10 m of RG-
8A/U cable to an antenna that has an input resistance of 50 + j50 . Determine the reflection
coefficient (L).
a) 0.324116.5o b) 0.324116.5o c) 0.44763.5o d) 0.447 63.5o
Explanation / Answer
2. What is the device which superimposes information onto a high-frequency signal for
transmission?
Answer:Modulator
In conductor at high frequencies, most of the current flow is at the outer surface of the conductor,
This phenomena is known as;?
Answer:Skin effect
27. Which multiplexing technology multiplexes multiple optical carrier signals on a single optical fiber?
Answer:Frequency division multiplexing
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