My Personal Study - Volume 1
- 1.
What is an example of analog-to-digital and digital-analog techniques?
- A.
Amplitude Modulation (AM) and Frequency Modulation (FM)
- B.
Pulse Code Modulation (PCM) and Frequency Key Shifting (FSK)
- C.
Phase Modulation (PM) and Quadrature Phase Shift Keying (QPSK)
- D.
Pulse Code Modulation (PCM) and continuously variable slope delta (CVSD)
Correct Answer
B. Pulse Code Modulation (PCM) and Frequency Key Shifting (FSK)Explanation
FSK
We use FSK to convert a digital signal to analog form by varying the frequency, or the pitch, of the
carrier signal. This type of modulation changes the center frequency from one value to another
depending on state of the digital input.
Digital modulation
The definition of digital modulation is the conversion of an analog signal (the information) into a
digital signal (the carrier).
PCM
PCM 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). The signal is based on an analog signal that has
already been modulated (by using PAM, PDM, or PPM). The pulses are grouped into any of a
predefined number of different levels using a quantizer; each of the possible levels is represented by a
unique bit stream. The number of possible values in this stream determines the granularity of the
modulation.Rate this question:
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- 2.
What converts analog signal information into an analog carrier signal?
- A.
Delta modulation (DM).
- B.
Digital modulation.
- C.
Analog modulation.
- D.
Adaptive modulation.
Correct Answer
C. Analog modulation.Explanation
The definition of analog modulation is the conversion of an analog signal (the information) into another analog signal (the carrier).Rate this question:
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- 3.
What converts analog signal information into a digital carrier signal?
- A.
Delta modulation (DM).
- B.
Analog modulation.
- C.
Digital modulation.
- D.
Adaptive modulation.
Correct Answer
C. Digital modulation.Explanation
Digital modulation
The definition of digital modulation is the conversion of an analog signal (the information) into a digital signal (the carrier). This is done by converting an analog wave into discrete pulses, taking multiple samples, and converting the samples into a digital signal. The type of modulation used depends on the feature of a pulse that is varied to encode an analog signal that is being converted to digital form. Digital modulation techniques can be pulse or delta modulation.Rate this question:
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- 4.
The information-carrying components that occur on either side of a carrier are called
- A.
Sidebands
- B.
Sine waves.
- C.
Frequency translators.
- D.
Modulating frequencies.
Correct Answer
A. SidebandsExplanation
Notice that the output signal includes two bands of frequencies: one at frequencies above the carrier, fc, and one below the carrier. These we call the upper sideband and lower sideband, respectively. The upper sideband (USB) has the same shape and orientation as the band of modulating signal frequencies. The lower sideband (LSB), however, is the mirror image of the original modulating signal.
Since both sidebands contain frequency-translated copies of the modulating signal, either the upper or the lower sideband can be used by itself to transmit the information signal.Rate this question:
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- 5.
Amplitude modulation (AM) requires a bandwidth that is
- A.
Twice that of the modulating signal.
- B.
Half that of the modulating signal.
- C.
Twice that of the carrier signal.
- D.
Half that of the carrier signal.
Correct Answer
A. Twice that of the modulating signal.Explanation
In general, AM requires twice the bandwidth to transmit as does the modulating signal alone.Rate this question:
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- 6.
The upper sideband in a single-sideband suppressed carrier (SSBSC) modulation is eliminated by
- A.
Filtering.
- B.
Detection.
- C.
Compression.
- D.
Companding.
Correct Answer
A. Filtering.Explanation
This process is shown in figure 1–5. Here, we use a filter that passes only the signal components in the frequency range between fc – fH and fc – fL. Thus, the output of the filter contains only the lower sideband.Rate this question:
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- 7.
We can express the 6-to–1 improvement of the single-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.Explanation
The predominant characteristic of single-sideband modulation is that all of the transmitter power can be used for the transmission of the information signal located in one sideband without a carrier. A transmitter with a 1500-watt output can then transmit one sideband at the full 1500 watts. All of that signal power is used at the receiver so that SSBSC represents a 6-to-1 improvement over other forms of AM like double-sideband suppressed carrier (DSBSC), where only 250 watts of the 1,500 transmitted went into each sideband. We can express the 6-to-1 improvement of SSBSC over DSBSC as 8 decibels (dB) of improvement.Rate this question:
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- 8.
The only basic waveform in nature is a
- A.
Carrier wave.
- B.
Pure sine wave.
- C.
Resultant wave.
- D.
Composite wave.
Correct Answer
B. Pure sine wave.Explanation
The only basic waveform in nature is a pure sine wave; any other waveform is a “composite” or “resultant” wave.Rate this question:
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- 9.
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).Explanation
The second type of composite waveform is found in AM. As long as 100-percent modulation is not exceeded and/or distortion is not present in the modulating signal, there are only two sidebands for each frequency of modulating signal.Rate this question:
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- 10.
If 100 percent modulation is exceeded and there is distortion in the modulating signal, additional sidebands are generated. We identify these sidebands as what?
- A.
Transmitted intelligence.
- B.
Intensity of speech.
- C.
Composite waves.
- D.
Splatter.
Correct Answer
D. Splatter.Explanation
However, if 100-percent modulation is exceeded and/or there is distortion in the modulating signal, additional sidebands are generated because of the harmonic content of the distorted modulating signal. These additional sidebands, known as splatter, cause unwanted bandwidth and distortion in the transmitted AM signal.Rate this question:
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- 11.
The amount of deviation in a frequency modulation (FM) signal is directly proportional to the modulating signal’s
- A.
Phase.
- B.
Amplitude.
- C.
Frequency.
- D.
Amplitude and frequency.
Correct Answer
B. Amplitude.Explanation
Before we go further into FM, let’s recap the two rules we just established:
1. Rate of deviation in FM is proportional to the cycle rate (frequency) of the modulating signal.
2. Amount of deviation in FM is proportional to the amount (amplitude) of the modulating signal.Rate this question:
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- 12.
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.Explanation
The relationship of the modulating audio to the change in the phase shift in PM is easy to see, once you understand AM and FM principles. Again we can establish two clear-cut rules of PM:
1. The amount of phase shift is proportional to the amplitude of the modulating signal (that is, if a 10-volt signal causes a phase shift of 20 degrees, then a 20-volt signal causes a phase shift of 40 degrees).
2. The rate of phase shift is proportional to the frequency of the modulating signal (that is, if the carrier were modulated with a 1-kHz tone, the carrier would advance and retard, in phase, 1,000 times each second).Rate this question:
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- 13.
What form of modulation is insensitive to signal variations?
- A.
Delta.
- B.
Frequency shift keying (FSK).
- C.
Pulse-amplitude modulation (PAM).
- D.
Binary-phase shift keying or bi-phase shift keying (BPSK).
Correct Answer
D. Binary-phase shift keying or bi-phase shift keying (BPSK).Explanation
You have probably realized some of the advantages PM has over the other forms of modulation covered so far. One distinct advantage of BPSK is its insensitivity to level variations. This enables it to transmit low frequencies (including zero frequency by transmitting a steady mark or space condition). Theoretically, this makes PM the best technique for a given bandwidth with a given baud rate because it uses only one carrier frequency. At higher transmission speeds, BPSK allows you to transmit using the same channel bandwidth used at the lower speeds. However, there are some distinct disadvantages to PM.Rate this question:
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- 14.
In quadrature-phase shift keying (QPSK) the radio frequency (RF) bandwidth for a quadriphase signal is what of that required by a bi-phase signal, given the same data rate.
- A.
Four times.
- B.
Double.
- C.
Half.
- D.
The same.
Correct Answer
C. Half.Explanation
The two main reasons for quadriphase, despite its complexity, are as follows:
1. A quadriphase signal is not as seriously degraded as a bi-phase signal when passed through a nonlinear device simultaneously with interference.
2. The RF bandwidth for a quadriphase signal is half that required by a bi-phase signal, given the same data rate. Alternatively, twice as much data might be transmitted in the same bandwidth with a quadriphase signal as with a bi-phase signal.Rate this question:
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- 15.
What is the main advantage of differential phase shift keying (DPSK)?
- 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.Explanation
The main advantage of DPSK is that it requires a less complex receiver than a basic PSK signal. A demodulator need only detect changes in phase, not absolute phase values. The presence of the carrier is not required for detection.Rate this question:
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- 16.
Which of the following is not considered an analog modulation techniques?
- 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).Explanation
PAM, PDM, and PPM are true analog pulse-modulation techniques. Although PCM and DM are called pulse-modulation techniques; they are really digital-coding techniques.Rate this question:
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- 17.
The form of pulse modulation in which the pulse is varied within a set range of positions is known as
- A.
Pulse-amplitude modulation (PAM).
- B.
Pulse-duration modulation (PDM).
- C.
Pulse-position modulation (PPM).
- D.
Pulse-code modulation (PCM).
Correct Answer
C. Pulse-position modulation (PPM).Explanation
In TDM subsystems using PPM, the signal amplitudes at the sampling instants vary the pulse’s position in time. This process is illustrated in figure 1–29 C. Once again, only four distinct signal amplitudes are used. Therefore, four distinct pulse positions are needed.Rate this question:
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- 18.
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.Explanation
Quantized analog modulation reduces the analog signals to discrete (digital) pulses that describe the analog signals according to various arbitrary rules. This process is actually analog-to-digital conversion rather than modulation and has two principal advantages.Rate this question:
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- 19.
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.Explanation
Figure 1–35 illustrates the PCM process for 16 quantized steps. The number of steps needed is equal to 2n, where (n) is the number of code bits needed for the largest character. Thus, the 16-step system requires 4 bits per character (24=16) and a 128-step system requires 7 bits per character (27=128) to describe the quantized analog samples.Rate this question:
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- 20.
The process of coding pulse code modulation (PCM) quantized pulses to make them a constant duration and amplitude is
- A.
Encoding.
- B.
Companding.
- C.
Uniform quantizing.
- D.
Nonuniform quantizing.
Correct Answer
A. Encoding.Explanation
Encoding
The capability for regeneration of quantized pulses can be further enhanced by coding the pulses to make them of constant duration and amplitude before transmission. This helps the signal to be recognized so it can be reproduced—whether the pulse is received or not.Rate this question:
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- 21.
In Time Division Multiplexing (TDM), the transmitting multiplexer will put a bit or a byte from each of the incoming lines into a specifically allocated what?
- A.
Channel.
- B.
Trunk.
- C.
Time slot.
- D.
Port.
Correct Answer
C. Time slot.Explanation
The transmitting multiplexer will put a bit or a byte from each of the incoming lines into a specifically allocated time slot, and the demultiplexer at the other end of the system, outputs the bits or bytes to their appropriate lines (timeslots) at their operating speeds.Rate this question:
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- 22.
The two major types of frame structures are
- A.
Low speed and high speed.
- B.
High speed and EBCDIC.
- C.
CCITT and low speed.
- D.
EBCDIC and CCITT.
Correct Answer
C. CCITT and low speed.Explanation
There are two major types of frame structures:
1. Low speed frame – used for rates below 384.2 kbps and is composed of a number of 8 bit slots with each slot holding one character
2. Consultative Committee for International Telephony and Telegraphy (CCITT) frame –used for data rates above 384.2 kilobytes per second (kb/s) and uses subframes (P1 and P2) to maintain sync during longer data frames.Rate this question:
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- 23.
The method of multiplexing the T1 multiplexer uses is
- A.
Frequency division.
- B.
Binary division.
- C.
Pulse division.
- D.
Time division.
Correct Answer
D. Time division.Explanation
T1 uses the TDM process (fig. 1–38). These inputs can be a combination of digital, video, and audio signals. Audio signals must first be digitized using the PCM process, where the audio signals are changed into 8 bit digital codes.Rate this question:
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- 24.
Wave-division multiplexing (WDM) creates the virtual channels for multiplexing them together for transmission 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.Explanation
While white light passes through a prism it is split into a spectrum of colors, where each color has its own wavelength. WDM does the same thing; using an optical device, it sends light through to create the virtual channels using different wavelengths or lambdas then it multiplexes them together for transmission. In WDM, each device connected to the WDM is given a different wavelength of light or different color in the spectrum that allows the devices to pass together across the fiber within the same area of the light spectrum.Rate this question:
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- 25.
The most common wave-division multiplexing (WDM) system uses how many wavelengths?
- A.
One wavelength.
- B.
Two wavelengths.
- C.
Three wavelengths.
- D.
Four wavelengths.
Correct Answer
B. Two wavelengths.Explanation
The most common WDM system uses two wavelengths, although four or more-wavelength systems are available.Rate this question:
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- 26.
Individual pulses within a digital signal are
- A.
Bits.
- B.
Bytes.
- C.
Codes.
- D.
Blocks.
Correct Answer
A. Bits.Explanation
In digital signals, we call each condition, state, or pulse a binary digit. We shorten this term to “bit.”Rate this question:
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- 27.
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.Explanation
When we express the term “bit” with regard to time, we have bits per second (b/s). This simply means that we can move a certain number of symbols, states, or conditions in 1 second. This method is commonly used in data systems to express signaling speed for equipment.Rate this question:
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- 28.
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.Explanation
Bit count integrity problems are primarily caused by system delay or timing faults. Remember, the bit count integrity is only concerned with the number of bits received in a specific time and not with errored bits.Rate this question:
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- 29.
Three categories of synchronization used in digital data circuits are
- A.
Synchronous, asynchronous, and isochronous.
- B.
Isochronous, asynchronous, and bisynchronous.
- C.
Nonsynchronous, bisynchronous, and synchronous.
- D.
Asynchronous, bisynchronous, and nonsynchronous.
Correct Answer
A. Synchronous, asynchronous, and isochronous.Explanation
Timing for digital devices fall into three categories: synchronous, asynchronous, and isochronous. These terms characterize the methods used to synchronize the send and receive devices.Rate this question:
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- 30.
Which option is a characteristic of 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.Explanation
Synchronous operation requires no synchronizing pulses in the signal stream, and all bits are the same length in time. In synchronous operation, the receiving device is adjusted automatically to the speed of the transmitting device by comparing the speed of the incoming signal with the time base of the receiving device.Rate this question:
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- 31.
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.Explanation
An asynchronous signal is any signal that contains synchronizing bits within its signal stream. This method of synchronization was at one time the most common form. It is identified by a start pulse or bit at the beginning and a stop pulse or bit at the end of each character.Rate this question:
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- 32.
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.Explanation
NRZ-M (mark). The information is contained in the transition, and there’s a transition from one state to the other only when a mark bit is sent.Rate this question:
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- 33.
In what type of signal does the signal level move to one of the discrete signal levels, but returns to the zero level after a predetermined time?
- A.
Non-return-to-zero (NRZ) level.
- B.
Non-return-to-zero mark.
- C.
Non-return-to-zero space.
- D.
Return-to-zero.
Correct Answer
D. Return-to-zero.Explanation
RZ
When a signal transition occurs, the signal level moves to one of the discrete signal levels, but after a predetermined time (normally 50 percent of a bit), it returns to zero voltage (RZ).Figure 2–5 shows the three most common signal formats in the DII.Rate this question:
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- 34.
Which statement best describes an alternate mark inversion (AMI) signal?
- A.
The information is transmitted in three different voltage levels.
- B.
A logic one is transmitted as positive voltage if the previous logic one was negative.
- C.
The level always returns to zero for 50 percent of the bit cycle after every transition.
- D.
Bipolar violations are intentionally inserted into a data signal to break up long strings of zeros.
Correct Answer
B. A logic one is transmitted as positive voltage if the previous logic one was negative.Explanation
AMI
In AMI, alternate marks (or logic ones) are inverted in polarity. If a logic one is transmitted, it is represented by a positive voltage if the previous logic one was negative.Conversely, it is represented by negative voltage if the previous one was positive. Logic zeros are represented by zero voltage. This results in a three-level digital signal.Rate this question:
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- 35.
Digital coding techniques such as binary with eight-zero substitution (B8ZS) are becoming more popular because they are designed to
- A.
Maintain ones density standards.
- B.
Provide error-free signaling.
- C.
Operate at higher data rates.
- D.
Eliminate bipolar violations.
Correct Answer
A. Maintain ones density standards.Explanation
Because of the ones density problem, coding techniques such as B8ZS are getting more popular.Rate this question:
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- 36.
Which statement best describes a binary with eight-zero substitution (B8ZS) signal?
- A.
The information is transmitted in three different voltage levels.
- B.
A logic one is transmitted as positive voltage if the previous logic one was negative.
- C.
The level always returns to zero for 50 percent of the bit cycle after every transition.
- D.
Bipolar violations are intentionally inserted into a data signal to break up long strings of zeros.
Correct Answer
D. Bipolar violations are intentionally inserted into a data signal to break up long strings of zeros.Explanation
B8ZS intentionally inserts bipolar violations (BPV) into a data signal to break up long strings of zeros.Rate this question:
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- 37.
The major difference between conditioned di-phase (CDI) and other schemes is the
- A.
Lack of mid-bit transitions.
- B.
Use of mid-bit transitions for timing.
- C.
Data being encoded in the mid-bit transitions.
- D.
Voltage levels used for signaling the mid-bit transitions.
Correct Answer
B. Use of mid-bit transitions for timing.Explanation
CDI is a binary, polar, state transition encoding scheme that is used almost exclusively in military tactical applications. One major difference in this scheme is the use of mid-bit transitions for timing.Rate this question:
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- 38.
How many bits are in the D4 framing sequence?
- A.
8.
- B.
12.
- C.
24.
- D.
48.
Correct Answer
B. 12.Explanation
A D4 frame consists of 192 data bits. The data bits represent 24 channels times 8 bits per channel. A single framing bit is added for a total of 193 bits. One framing bit from 12 consecutive frames is added to create a 12-bit framing sequence.Rate this question:
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- 39.
How many bits are in the extended superframe format (ESF) framing sequence?
- A.
8.
- B.
12.
- C.
24.
- D.
48.
Correct Answer
C. 24.Explanation
ESF framing
The ESF frame is based on the D4 frame. The difference between ESF and D4 framing is that the ESF superframe consists of 24 frames to create a 24-bit framing sequence. In addition to frame synchronization, the framing sequence is used for error detection and link performance management.Rate this question:
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- 40.
What communications control signal uses a two-frequency dialing combination?
- A.
Pulse dialing.
- B.
Tone dialing.
- C.
Digit dialing.
- D.
Address dialing.
Correct Answer
B. Tone dialing.Explanation
Tone dialing
In tone dialing, the address signaling is sent by a set of tones instead of pulses. Tone dialing uses a two-frequency combination that is associated with 12 push button keys. Each row and column of keys is associated with a predefined frequency.Rate this question:
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- 41.
What communications information signal uses a continuous 350- and 440-Hz frequency pair?
- A.
Dial tone.
- B.
Ringback signal.
- C.
Off-hook alert.
- D.
Call waiting.
Correct Answer
A. Dial tone.Explanation
Dial tone
A dial tone is a frequency pair used to convey informational signaling. For example, the generation of a continuous 350- and 440-Hz frequency pair by the switch equipment.Rate this question:
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- 42.
What communications information signal uses a signal cycled on and off for 0.5 second and contains the generation of a 480- and 620-Hz frequency pair?
- A.
Dial tone.
- B.
Busy signal.
- C.
Off-hook alert.
- D.
Call waiting.
Correct Answer
B. Busy signal.Explanation
Busy signal
The local switch equipment generates a busy signal to the sender when the receiver’s line is in use. For example, a signal cycled on and off for 0.5 second and contains the generation of a 480- and 620-Hz frequency pair.Rate this question:
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- 43.
What communications supervisory signal uses a continuous application of direct current voltage for signaling?
- A.
Record warning.
- B.
Fast busy signal.
- C.
Loop-start.
- D.
E and M.
Correct Answer
C. Loop-start.Explanation
Loop-start signaling
The loop-start or metallic loop signaling method uses a continuous application of direct current voltage.Rate this question:
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- 44.
When is the voltage applied in loop-start signaling?
- A.
When dial tone is present.
- B.
On-hook condition.
- C.
Off-hook condition.
- D.
During the ringback signal.
Correct Answer
C. Off-hook condition.Explanation
Loop-start signaling
The loop-start or metallic loop signaling method uses a continuous application of direct current voltage. The voltage or 48-volt battery is not activated until the telephone handset is lifted, off-hook. This action results in current flowing through the loop and signals the switch equipment to provide a dial tone. When the handset is returned to the cradle, on-hook, the current flowing through the loop is terminated.Rate this question:
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- 45.
In common associated signaling (CAS), what is the seventh bit in frames 6 and 12 used to convey signaling information known as?
- A.
Bit robbing.
- B.
Bit stuffing
- C.
Frame correction.
- D.
Frame enhancement.
Correct Answer
A. Bit robbing.Explanation
CAS signaling is associated with D4 framing, a 12-frame framing sequence. In CAS signaling, the seventh bit in frames 6 and 12 are “robbed” to convey signaling information. This is known as bit robbing.Rate this question:
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- 46.
In what common channel signaling (CCS) mode are the messages relating to signaling between two points conveyed directly interconnecting these signaling points?
- A.
Associated mode.
- B.
Nonassociated mode.
- C.
Quasi-associated mode.
- D.
Multi-associated mode.
Correct Answer
A. Associated mode.Explanation
CCS has three signaling modes:
1. Associated mode – The messages relating to signaling between two points are conveyed directly interconnecting these signaling points.
2. Nonassociated mode – The messages relating to signaling are conveyed over two or more links passing through one or more signaling points that are not the origin and the destination of the messages.
3. Quasi-associated mode – This is a subcase of the nonassociated mode. The path the messages take through the network is predetermined and fixed.Rate this question:
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- 47.
What are the two principle weighting characteristics in use with telecommunication circuit noise?
- A.
Institute of Electronic and Electrical Engineers and CCITT psophometric.
- B.
Noise analysis and CCITT psophometric.
- C.
CCITT psophometric and C-message.
- D.
C-message and noise analysis.
Correct Answer
C. CCITT psophometric and C-message.Explanation
The two principal weighting characteristics in current use are (1) CCITT (Consultative Committee for International Telephony and Telegraphy) psophometric, a noise weighting used in Europe with a noise (or level) meter called a psophometer, weighting and (2) C-message weighting.Rate this question:
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- 48.
While timing makes sure the equipment is sending and receiving bits at the same time intervals, synchronization makes sure 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.
- D.
Transmit equipment can find its place in the bit stream.
Correct Answer
C. Receive equipment can find its place in the bit stream.Explanation
While timing makes sure the equipment is sending and receiving bits at the same time intervals, synchronization makes sure that the receive equipment can find its place in the bit stream. It is imperative that the 8 bits from channel 1 on the transmit end are placed on channel 1 on the receive end. Since only 1s and 0s are transmitted, the equipment uses patterns of frame bits to distinguish positions in the data bit stream. We call these patterns framing formats.Rate this question:
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- 49.
What term is associated with the delay or lag introduced in the application of voltage from one section to the next?
- A.
Latency.
- B.
Phase delay.
- C.
Propagation constant.
- D.
Phase delay distortion.
Correct Answer
A. Latency.Explanation
Thus, a delay, also known as latency or lag, is introduced in the application of voltage from one section to the next. This delay, or propagation constant (propagation in this context means: to cause to move through a medium; transmit), varies according to frequency so that the various frequency components making up a voice intelligence or data signal arrive at differing times.Rate this question:
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- 50.
Attenuation distortion is caused by
- A.
A line loss for the various frequency components comprising a voice transmission.
- B.
The line loss, the distance of transmission lines, and faults in the transmission cables.
- C.
Faults in the transmission cables and the number of splices in the line varying with the frequency.
- D.
Differing attenuation rates for the various frequency components comprising a voice frequency transmission.
Correct Answer
D. Differing attenuation rates for the various frequency components comprising a voice frequency transmission.Explanation
Attenuation distortion
Attenuation basically means a reduction in energy, generally expressed in decibels. You can easily understand how information being sent or received via lines would be attenuated because of line loss, the distance of the transmission line, the number of splices, and faults in the cables. Therefore, we will not describe these areas of attenuation. However, attenuation (which varies with frequency) causes a type of distortion called, you guessed it, attenuation distortion. Differing attenuation rates for the various frequency components comprising a voice frequency transmission causes attenuation distortion.Refer again to the transmission line equivalent circuit in
figure 3–4.Rate this question:
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Mar 21, 2022Quiz Edited by
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Nov 01, 2011Quiz Created by
Ricktheguru
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