RCDD Practice Test Questions and
Answers 100% Pass Updated 2025
C - ✔✔If the input signal power to a communication system is 1 W and the output
power is 1 mW, the system attenuation is:
A. 3 dB
B. 20 dB
C. 30 dB
D. 40 dB
E. 1000 dB
B - ✔✔The signal at the input to a balanced twisted pair cable is 10 mW. The cable is
1000 feet long and has an attenuation of 1 dB per 100 feet. This cable is connected to
the input of a receiver. The noise level at the input to the receiver is 1 microwatt.
What is the signal-to- noise ratio (SNR) (dB) at the receiver input?
A. 10 dB
B. 30 dB
C. 40 dB
D. 60 dB
E. 100 dB
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,C - ✔✔A SONET OC-1 channel can carry 672 voice signals and has a data rate of
51.84 Mbps. ASONET OC-48 channel can carry 32,256 voice channels. What
MINIMUM data rate is required for the OC-48 channel?
A. 155 Mbps
B. 622 Mbps
C. 2.5 Gbps
D. 5 Gbps
E. 10 Gbps
A - ✔✔All of the following are nominal wavelengths for laser light sources EXCEPT:
A. 700 nm
B. 850 nm
C. 1300 nm
D. 1310 nm
E. 1550 nm
A - ✔✔A video camera has a coaxial cable output. The video signal is to be
distributed to devices that have balanced twisted pair inputs. The transition between
these two different transmission media can be accomplished by using a:
A. Balun
B. Converter
C. Modulator
D. Cross connect
E. Transceiver
C - ✔✔The public telephone system is an example of a __________ system.
A. Simplex
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,B. Half-duplex
C. Full-duplex
D. Purely analog
E. Purely digital
D - ✔✔Wave division multiplexing (WDM) is most similar to:
A. Amplitude modulation
B. Frequency modulation
C. Time division multiplexing
D. Frequency division multiplexing
E. Carrier sense multiple access with collision detection (CSMA/CD)
C - ✔✔You must place CAT6 cable above a factory floor with automated welding
machines and hammer forges. Of the following, what type of shielding would be
most effective?
A. Multi-layer braid
B. Foil and braid
C. Solid metallic conduit
D. Flex metallic conduit
E. Sch. 40 PVC conduit
D - ✔✔You must place a cable between 2 equipment locations with separate grounds
having a potential difference between them of 2.1 V rms. Which one of the following
cables shouldNOT be used?
A. Multimode
B. Singlemode
C. UTP
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, D. STP
A - ✔✔Two sinusoidal signals have the same amplitude (A) and the same frequency
(f). They differ in phase by 180 degrees. If these two signals are added together, the
result is a sinusoidal signal having an amplitude of:
A. Zero
B. 0.707A and a frequency of f
C. A and a frequency of 2f
D. 2A and a frequency of f
E. 2A and a frequency of 2f
A - ✔✔Composite conductors, although not generally recommended, may be used
in special circumstances because they provide all of the following advantages
EXCEPT:
A. Have good digital transmission characteristics
B. Lightweight
C. Inexpensive
D. Easy to produce
E. Easily embedded into other materials
D - ✔✔Which is an advantage of stranded conductors over solid conductors?
A. Less costly
B. Simpler terminations
C. Better high frequency performance
D. More flexible
E - ✔✔The conversion of an analog speech signal to a pulse code modulation (PCM)
digital signal involves all of the following steps EXCEPT:
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Answers 100% Pass Updated 2025
C - ✔✔If the input signal power to a communication system is 1 W and the output
power is 1 mW, the system attenuation is:
A. 3 dB
B. 20 dB
C. 30 dB
D. 40 dB
E. 1000 dB
B - ✔✔The signal at the input to a balanced twisted pair cable is 10 mW. The cable is
1000 feet long and has an attenuation of 1 dB per 100 feet. This cable is connected to
the input of a receiver. The noise level at the input to the receiver is 1 microwatt.
What is the signal-to- noise ratio (SNR) (dB) at the receiver input?
A. 10 dB
B. 30 dB
C. 40 dB
D. 60 dB
E. 100 dB
COPYRIGHT © 2025 BY EMILLY CHARLOTTE, ALL RIGHTS RESERVED 1
,C - ✔✔A SONET OC-1 channel can carry 672 voice signals and has a data rate of
51.84 Mbps. ASONET OC-48 channel can carry 32,256 voice channels. What
MINIMUM data rate is required for the OC-48 channel?
A. 155 Mbps
B. 622 Mbps
C. 2.5 Gbps
D. 5 Gbps
E. 10 Gbps
A - ✔✔All of the following are nominal wavelengths for laser light sources EXCEPT:
A. 700 nm
B. 850 nm
C. 1300 nm
D. 1310 nm
E. 1550 nm
A - ✔✔A video camera has a coaxial cable output. The video signal is to be
distributed to devices that have balanced twisted pair inputs. The transition between
these two different transmission media can be accomplished by using a:
A. Balun
B. Converter
C. Modulator
D. Cross connect
E. Transceiver
C - ✔✔The public telephone system is an example of a __________ system.
A. Simplex
COPYRIGHT © 2025 BY EMILLY CHARLOTTE, ALL RIGHTS RESERVED 2
,B. Half-duplex
C. Full-duplex
D. Purely analog
E. Purely digital
D - ✔✔Wave division multiplexing (WDM) is most similar to:
A. Amplitude modulation
B. Frequency modulation
C. Time division multiplexing
D. Frequency division multiplexing
E. Carrier sense multiple access with collision detection (CSMA/CD)
C - ✔✔You must place CAT6 cable above a factory floor with automated welding
machines and hammer forges. Of the following, what type of shielding would be
most effective?
A. Multi-layer braid
B. Foil and braid
C. Solid metallic conduit
D. Flex metallic conduit
E. Sch. 40 PVC conduit
D - ✔✔You must place a cable between 2 equipment locations with separate grounds
having a potential difference between them of 2.1 V rms. Which one of the following
cables shouldNOT be used?
A. Multimode
B. Singlemode
C. UTP
COPYRIGHT © 2025 BY EMILLY CHARLOTTE, ALL RIGHTS RESERVED 3
, D. STP
A - ✔✔Two sinusoidal signals have the same amplitude (A) and the same frequency
(f). They differ in phase by 180 degrees. If these two signals are added together, the
result is a sinusoidal signal having an amplitude of:
A. Zero
B. 0.707A and a frequency of f
C. A and a frequency of 2f
D. 2A and a frequency of f
E. 2A and a frequency of 2f
A - ✔✔Composite conductors, although not generally recommended, may be used
in special circumstances because they provide all of the following advantages
EXCEPT:
A. Have good digital transmission characteristics
B. Lightweight
C. Inexpensive
D. Easy to produce
E. Easily embedded into other materials
D - ✔✔Which is an advantage of stranded conductors over solid conductors?
A. Less costly
B. Simpler terminations
C. Better high frequency performance
D. More flexible
E - ✔✔The conversion of an analog speech signal to a pulse code modulation (PCM)
digital signal involves all of the following steps EXCEPT:
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