3c251 Volume 1
3C251 Volume 1. URE's only.
- 1.
What is an example of analog to digital and digital to analog techniques?
- A.
Amplitude modulation (AM) and frequency modulation (FM)
- B.
Pulse code modulation (PCM) and frequency shift key modulation (FSK)
- C.
Phase modulation (PM) and quadrature phase shift key (QPSK)
- D.
Pulse code modulation (PCM) and continuously variable slope delta (CVSD) modulation
Correct Answer
D. Pulse code modulation (PCM) and continuously variable slope delta (CVSD) modulation -
- 2.
What modulation technique is a complete digitization process since it converts an analog signal into one that is discrete with respect to both time and amplitude (or polarity)?
- A.
Pulse-amplitude modulation (PAM)
- B.
Pulse-duration modulation (PDM)
- C.
Pulse-width modulation (PWM)
- D.
Pulse-code modulation (PCM)
Correct Answer
D. Pulse-code modulation (PCM) -
- 3.
Amplitude modulation (AM) requires a bandwidth that is
- A.
Twice that of the modulating signal
- B.
Half that of the modulation signal
- C.
Twice that of the carrier signal
- D.
Half that of the carrier signal
Correct Answer
A. Twice that of the modulating signal -
- 4.
We can express the 6-to-1 improvement of the signal-sideband suppressed carrier (SSBSC) modulation over conventional amplitude modulation (AM) as
- A.
2 decibels (dB) of improvement
- B.
4 dB of improvement
- C.
6 dB of improvement
- D.
8 dB of improvement
Correct Answer
D. 8 dB of improvement -
- 5.
A modulated waveform that contains a carrier plus two sidebands for each modulation frequency is a description of
- A.
A phase modulation (PM)
- B.
A pulse modulation
- C.
A frequency modulation (FM)
- D.
An amplitude modulation (AM)
Correct Answer
D. An amplitude modulation (AM) -
- 6.
If 100 percent modulation is exceeded and there is distortion in the modulating signal, additional sidebands are generated. We identify these sideband as
- A.
Transmitted intelligence
- B.
Intensity of speech
- C.
Composite waves
- D.
Splatter
Correct Answer
D. Splatter -
- 7.
To prevent frequency modulation (FM) radio stations from interfering with each other, the Federal Communications Commission (FCC) has set limits that allow each station to cause its oscillator frequency to deviate no more than
- A.
20 kHz
- B.
50 kHz
- C.
75 kHz
- D.
88 kHz
Correct Answer
C. 75 kHz -
- 8.
The amount of phase shift in a phase modulation (PM) signal is directly proportional to the
- A.
Modulation index
- B.
Rate of phase shift
- C.
Frequency of the modulating signal
- D.
Amplitude of the modulating signal
Correct Answer
D. Amplitude of the modulating signal -
- 9.
Quadrature-phase shift keying (QPSK) requires
- A.
Half the bandwidth as does bi-phase shift keying (BPSK)
- B.
The same bandwidth as does BPSK
- C.
Twice the bandwidth as does BPSK
- D.
Four times the bandwidth as does BPSK
Correct Answer
A. Half the bandwidth as does bi-phase shift keying (BPSK) -
- 10.
What is the main advantage of differential phase shift keying (DSPK)?
- A.
Carrier presence is required to detect changes
- B.
It requires a less complex receiver than a basic phase shift keying (PSK) signal
- C.
It requires a more complex receiver than a basic PSK signal
- D.
The demodulator needs to detect changes in absolute phase values
Correct Answer
B. It requires a less complex receiver than a basic phase shift keying (PSK) signal -
- 11.
All of these are considered analog modulation techniques except
- A.
Pulse-amplitude modulation (PAM)
- B.
Pulse-duration modulation (PDM)
- C.
Pulse-position modulation (PPM)
- D.
Pulse-code modulation (PCM)
Correct Answer
D. Pulse-code modulation (PCM) -
- 12.
The form of pulse modulation that requires the pulse width to be varied to convoy intelligence is
- A.
Pulse-amplitude modulation (PAM)
- B.
Pulse-duration modulation (PDM)
- C.
Pulse-position modulation (PPM)
- D.
Pulse-code modulation (PCM)
Correct Answer
B. Pulse-duration modulation (PDM) -
- 13.
Quantized analog modulation is actually
- A.
Pulse-amplitude modulation (PAM)
- B.
Pulse-duration modulation (PDM)
- C.
Less tolerant of noise than frequency modulation (FM)
- D.
Analog-to-digital conversion
Correct Answer
D. Analog-to-digital conversion -
- 14.
Which type of pulse modulation is least affected by noise?
- A.
Pulse-amplitude modulation (PAM)
- B.
Pulse-duration modulation (PDM)
- C.
Pulse-position modulation (PPM)
- D.
Pulse-code modulation (PCM)
Correct Answer
D. Pulse-code modulation (PCM) -
- 15.
Pulse-code modulation (PCM) code words are assigned to each sample and correspond to its
- A.
Phase
- B.
Time slot
- C.
Amplitude
- D.
Frequency
Correct Answer
C. Amplitude -
- 16.
How many bits per character of a 16-step pulse-code modulation (PCM) system are used to describe the quantized analog sample?
- A.
3
- B.
4
- C.
5
- D.
8
Correct Answer
B. 4 -
- 17.
The process of coding pulse code modulation (PCM) quantized pulses to make them a constant duration and amplitude is
- A.
Encoding
- B.
Compounding
- C.
Uniform quantizing
- D.
Nonuniform quantizing
Correct Answer
A. Encoding -
- 18.
Noise in delta modulation (DM) can be reduced by varying the approximation signal step size in accordance with the input signal's
- A.
Speed
- B.
Phase
- C.
Amplitude
- D.
Frequency
Correct Answer
C. Amplitude -
- 19.
What modulation technique varies the step size in accordance with the magnitude of the input signal's amplitude?
- A.
Delta modulation (DM)
- B.
Frequency modulation (FM)
- C.
Pulse-code modulation (PCM)
- D.
Continuous variable slope delta modulation (CVSD)
Correct Answer
D. Continuous variable slope delta modulation (CVSD) -
- 20.
Continuous variable slope delta (CVSD) modulation circuitry includes a pulse-amplitude modulator and a
- A.
Low-pass filter
- B.
High-pass filter
- C.
Bandpass filter
- D.
Band-reject filter
Correct Answer
C. Bandpass filter -
- 21.
Which modulation technique was developed to reduce signal loss and noise in a tactical environment?
- A.
Delta modulation (DM)
- B.
Pulse-code modulation (PCM)
- C.
Conditioned diphase interface modulation (CDI)
- D.
Adaptive differential pulse-code modulation (ADPCM)
Correct Answer
A. Delta modulation (DM) -
- 22.
Up to what percentage of speech is redundant?
- A.
35
- B.
45
- C.
65
- D.
75
Correct Answer
D. 75 -
- 23.
The accepted standard for the voice frequency band is
- A.
300 to 1,600 hertz (Hz)
- B.
300 to 2,600 Hz
- C.
300 to 3,400 Hz
- D.
300 to 3,800 Hz
Correct Answer
C. 300 to 3,400 Hz -
- 24.
Noise may be introduced into speech signals by thermal agitation and
- A.
Power variations
- B.
Amplitude variations
- C.
Black body radiation
- D.
Molecular breakdown of electronic components
Correct Answer
C. Black body radiation -
- 25.
Bits are taken from an input channel data stream at a rate at twice the highest frequency appearing in the intelligence signal we call
- A.
The sampling rate
- B.
Pulse-bit stuffing
- C.
Pulse-code modulation (PCM)
- D.
Elastic storage implementation
Correct Answer
A. The sampling rate -
- 26.
Which of these sampling rates is correct for a time division multiplexing (TDM) channel if the highest frequency appearing in the channel is 4 kilohertz (kHz)?
- A.
4 kHz
- B.
8 kHz
- C.
12 kHz
- D.
16 kHz
Correct Answer
B. 8 kHz -
- 27.
Having marker pulses at the beginning of each frame of a time-division multiplexing (TDM) signal is one method of
- A.
Encryption
- B.
Synchronization
- C.
Sampling the signal
- D.
Decreasing bandwidth required
Correct Answer
B. Synchronization -
- 28.
What modulation format is usually used with time slot interchange (TSI)?
- A.
Phase modulation (PM)
- B.
Pulse code modulation (PCM)
- C.
Pulse-duration modulation (PDM)
- D.
Pulse-amplitude modulation (PAM)
Correct Answer
B. Pulse code modulation (PCM) -
- 29.
How are incoming and outgoing channels connected within the time slot interchange?
- A.
By physical channel
- B.
By a switch matrix
- C.
By circuit identifier
- D.
By time
Correct Answer
D. By time -
- 30.
How are channels connected in space division multiplexing?
- A.
By virtual channel
- B.
By a switch matrix
- C.
By circuit identifier
- D.
By time
Correct Answer
B. By a switch matrix -
- 31.
Which multiplex scheme periodically redefines the length of its frames?
- A.
Asynchronous time division multiplexing (TDM)
- B.
Frequency data multiplexing (FDM)
- C.
Synchronous TDM
- D.
Isochronous TDM
Correct Answer
A. Asynchronous time division multiplexing (TDM) -
- 32.
In pulse-code modulation (PCM) systems, synchronizing bits may be inserted
- A.
Only at the beginning of a frame
- B.
Only at the end of a frame
- C.
Throughout a frame
- D.
Between frames
Correct Answer
C. Throughout a frame -
- 33.
Which type of time-division multiplexing (TDM) synchronization recovers clock from the traffic signal?
- A.
Asynchronous
- B.
Isochronous
- C.
Synchronous
- D.
Pulse stuffing
Correct Answer
A. Asynchronous -
- 34.
In a synchronous system, performance of all operations is controlled by a
- A.
Step pulse
- B.
Master clock
- C.
Start-stop pulse
- D.
Synchronization pulse
Correct Answer
B. Master clock -
- 35.
A synchronizing technique used to overcome propagation delay in time-division multiplexing(TDM) systems is
- A.
Isochronous
- B.
Master clock
- C.
Pulse stuffing
- D.
Synchronization pulse
Correct Answer
C. Pulse stuffing -
- 36.
Which module supervises AN/FCC-100(V) 9 operation and communicates with all the other AN/FCC-100(V) 9 modules and sub-assemblies?
- A.
Processor module
- B.
Aggregate module
- C.
Port carrier module
- D.
Interface module
Correct Answer
A. Processor module -
- 37.
Which module transfers data between the local AN/FCC-100(V) 9 internal high-speed data bus and the transmission path to the remote AN/FCC-100(V) 9 unit?
- A.
Multiplexer/demultiplexer (mux/demux) module
- B.
Aggregate module
- C.
Port carrier module
- D.
Interface module
Correct Answer
B. Aggregate module -
- 38.
Which module provides the interface and termination capability for two pieces of data terminal equipment (DTE) and is designed to accept four plug-in sub modules which interface the DTEs to the multiplexer?
- A.
Processor module
- B.
Aggregate module
- C.
Port carrier module
- D.
Interface module
Correct Answer
C. Port carrier module -
- 39.
Which module is the communication link between the AN/FCC-100(V) 9 and operator's panel or an external control terminal?
- A.
Processor module
- B.
Aggregate module
- C.
Port carrier module
- D.
Interface module
Correct Answer
D. Interface module -
- 40.
Wave-division multiplexing (WDM) creates the virtual channels for multiplexing them together for transmissions by using different
- A.
Wavelengths or lambdas
- B.
Wavelengths or gammas
- C.
Frequencies or lambdas
- D.
Frequencies or gammas
Correct Answer
A. Wavelengths or lambdas -
- 41.
What wave-division multiplexing (WDM) technology sends a large number of optical signals closely together?
- A.
WDM
- B.
Coarse wave division multiplexing (CWDM)
- C.
Dense wave division multiplexing (DWDM)
- D.
Long wave division multiplexing (LDWDM)
Correct Answer
C. Dense wave division multiplexing (DWDM) -
- 42.
What unit is most commonly used in data systems to express signaling speed?
- A.
Baud
- B.
Baudot
- C.
Sense interface
- D.
Bits per second
Correct Answer
D. Bits per second -
- 43.
Bit count integrity problems are primarily caused by
- A.
Impedance mismatch
- B.
System timing faults
- C.
Improper equipment settings
- D.
Changes in atmospheric conditions
Correct Answer
B. System timing faults -
- 44.
Three categories of synchronization used in digital data circuits are
- A.
Synchronous, asynchronous, and isochronous
- B.
Synchronous, asynchronous, and bi-synchronous
- C.
Nonsychronous, bi-synchronous, and synchronous
- D.
Asynchronous, bi-synchronous, and nonsynchronous
Correct Answer
A. Synchronous, asynchronous, and isochronous -
- 45.
In synchronous data operation
- A.
Timing pulses are transmitted within the signal stream
- B.
Start and stop pulses control data transmission
- C.
System timing is not of critical importance
- D.
All data bits are the same length in time
Correct Answer
D. All data bits are the same length in time -
- 46.
A digital signal that contains synchronizing bits within the signal stream describes
- A.
Synchronous operation
- B.
Asynchronous operation
- C.
Synchronous and/or isochronous operation
- D.
Asynchronous and/or synchronous operation
Correct Answer
B. Asynchronous operation -
- 47.
In communications, what is essential for continuous error-free performance?
- A.
Strong signal
- B.
Good timing
- C.
Standardized signal format
- D.
Error correction software
Correct Answer
B. Good timing -
- 48.
While timing ensures the equipment is sending and receiving bits at the same time intervals, synchronization ensures that the
- A.
Receive equipment timing is set properly
- B.
Transmit equipment timing is set properly
- C.
Receive equipment can find its place in the bit stream properly
- D.
Transmit equipment can find its place in the bit stream properly
Correct Answer
C. Receive equipment can find its place in the bit stream properly -
- 49.
How many signal levels does an return-to-zero alternate mark inversion (RZ AMI) signal have?
- A.
1
- B.
2
- C.
3
- D.
4
Correct Answer
C. 3 -
- 50.
In what type of signal is the information contained in the transition, and there is a transition from one state to the other only when a mark bit is sent?
- A.
Non-return-to-zero (NRZ) level
- B.
Non-return-to-zero mark
- C.
Non-return-to-zero space
- D.
Return-to-zero level
Correct Answer
B. Non-return-to-zero mark -
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Jan 15, 2013Quiz Edited by
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