3d1x2 Skt Book 1

109 Questions | By Esshlman | Last updated: Apr 6, 2013 | Total Attempts: 161

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Questions and Answers

1.

What is the process, or result of the process, of modifying any characteristic of an information singal or carrier signal so that it varies in step with the instantaneous value of another information signal?
- A.
  
  Multiplexing
- B.
  
  Modulation
- C.
  
  Conversion
- D.
  
  Manipulating
2.

What is the conversion of an analog signal into another analog signal?
- A.
  
  Analog Modulation
- B.
  
  Pulse Duration Modulation
- C.
  
  Digital Modulation
- D.
  
  Pulse Code Modulation
3.

Which of these is not a form of analog modulation?
- A.
  
  Frequency Modulation
- B.
  
  Phase Modulation
- C.
  
  Amplitude Modulation
- D.
  
  Bandwidth Modulation
4.

Which of these is not a basic type of digital conversion techniques?
- A.
  
  Amplitude Shift Keying(ASK)
- B.
  
  Binary Shift Keying(BSK)
- C.
  
  Frequency Shift Keying(FSK)
- D.
  
  Phase Shift Keying(PSK)
5.

Amplitude Shift Keying(ASK) is also know as ______ because the amplitude of the carrier was either on or off depending on the state of the digital input.
- A.
  
  On-Off Keying(OOK)
- B.
  
  On Keying(OK)
- C.
  
  Off Keying(OK)
- D.
  
  Duplex Keying(DK)
6.

____ is the simplest form of Phase Modulation. There are two phase shifts (0 degrees or 180 degrees) for data transmission depending on whether a binary 1 or 0 is to be transmitted.
- A.
  
  Phase Shift Keying(PSK)
- B.
  
  Differential Phase-Shift Keying(DPSK)
- C.
  
  Quadrature Phase-Shift Keying(QPSK)
- D.
  
  Binary Phase-Shift Keying(BPSK)
7.

What uses four different carrier phases (0 degrees, 90 degrees, 180 degrees, and 270 degrees) to represent two data transmission bits. For example, to send 00, the phase changes by 0 degrees.
- A.
  
  Differential Phase-Shift Keying(DPSK)
- B.
  
  Binary Phase-Shift Keying(BPSK)
- C.
  
  Quadrature Phase-Shift Keying(QPSK)
- D.
  
  Phase Shift Keying(PSK)
8.

______ encodes different digital values as changes in signal phase. This is easier to implement and is more robust than PSK because____ looks for differences, rather than specific values. This form of modulation can be found in local area network technologies.
- A.
  
  Differential Phase-Shift Keying(DPSK)
- B.
  
  Phase-Shift Keying(PSK)
- C.
  
  Binary Phase-Shift Keying(BPSK)
- D.
  
  Quadrature Phase-Shift Keying(QPSK)
9.

What is a combination of AM and PM? We use this to convert a digital signal to analog form by varying the amplitude and phase of the carrier signal. Using this method of modulation you are able to encode up to four data bits for transmission. This is also similar to QPSK.
- A.
  
  Dual Modulation(DM)
- B.
  
  Combined Modulation(CM)
- C.
  
  Quadrature Amplitude Modulation(QAM)
- D.
  
  AM-PM Modulation(AMPMM)
10.

What is the conversion of an analog signal into a digital signal? This is done by converting an analog wave into discrete pulses, taking multiple samples, and converting the samples into a digital signal.
- A.
  
  Digital Modulation
- B.
  
  Phase Modulation
- C.
  
  Discrete Pulse Modulation
- D.
  
  Sample Modulation
11.

What varies one or more parameters of a pulse according to a modulating signal to transmit the desired information?
- A.
  
  Pulse Modulation
- B.
  
  Phase Modulation
- C.
  
  Frequency Modulation
- D.
  
  Amplitude Modulation
12.

____ is the simplest kind of pulse-modulation technique and is amplitude-modulated. This is used for time-division multiplexing(TDM) and differs from AM mainly in the use of a rectangular pulse train rather than a sine wave for the carrier signal.
- A.
  
  Pulse-amplitude Modulation
- B.
  
  Pulse-duration Modulation
- C.
  
  Pulse-position Modulation
- D.
  
  Pulse-code Modulation
13.

This is another method used for TDM. ____ is also known as pulse-width modulation(PWM), pulse-length modulation(PLM), or pulse-time modulation(PTM). In ____ the pulse duration, or width, of each sample pulse is varied to encode an analog signal at the point of sampling. This method is less affected by noise than the PAM method.
- A.
  
  Pulse-duration Modulation
- B.
  
  Pulse-amplitude Modulation
- C.
  
  Pulse-position Modulation
- D.
  
  Pulse-code Modulation
14.

____ is used in military TDM equipment. ____ uses a pulse time method that represents an analog signal by varying the positioning (the time displacement) of a discrete pulse within a bit interval. The position is varied according to the sampled value of an analog signal.
- A.
  
  Pulse-position Modulation
- B.
  
  Pulse-code Modulation
- C.
  
  Pulse-duration Modulation
- D.
  
  Pulse-amplitude Modulation
15.

_____ 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).
- A.
  
  Pulse-code Modulation
- B.
  
  Pre-modulated Modulation
- C.
  
  Analog Modulation
- D.
  
  Complete Modulation
16.

The pulses of PCM are grouped into any of a predefined number of different levels using a ______; 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.
- A.
  
  Quantizer
- B.
  
  Compander
- C.
  
  Transformer
- D.
  
  Converter
17.

This is a variation of PCM. Amplitudes are represented using 4-bit values (rather than the 8 bits used in PCM), and a 32Kbps data-transfer rate is used (rather than 64Kbps, as in PCM).
- A.
  
  Adaptive differential pulse-code modulation(ADPCM)
- B.
  
  Amplitude differential pulse-code modulation(ADPCM)
- C.
  
  Amplitude difference pulse-code modulation(ADPCM)
- D.
  
  Adaptive difference pulse-code modulation(ADPCM)
18.

_____ converts an analog signal (voice signal) by scanning it a specified amount of times (Ex. 32,000 times a second). A sample is taken at a specified time. If the value of the sample is different than it was at the previous scan, the digital signal is modified by a discrete step. If the value is greater, a positive '1' is sent. If the value is smaller, a negative '0' is sent.
- A.
  
  Delta Modulation(DM)
- B.
  
  Digital Modulation(DM)
- C.
  
  Discrete Modulation(DM)
- D.
  
  Pulse-code Modulation(PCM)
19.

What is a variation of DM where a signal's step size may vary from sample to sample?
- A.
  
  Adaptive Delta Modulation(ADM)
- B.
  
  Step Size Modulation(SSM)
- C.
  
  Differential Modulation(DM)
- D.
  
  Variation Modulation(VM)
20.

This modulation varies the signal step size according to the input signal amplitude. At lower input signals, smaller step sizes minimize quantizing noise. At higher signal levels, larger step sizes minimize slope overload.
- A.
  
  Continuously Variable Slope Delta Modulation(CVSD)
- B.
  
  Amplitude Modulation(AM)
- C.
  
  Adaptive Delta Modulation(ADM)
- D.
  
  Step Size Delta Modulation(SSDM)
21.

_____ is historically one of the oldest forms of modulation. In this modulation, the amplitude of the carrier signal is varied according to the modulating signal. In the early days of vacuum-tube transmitters, this was achieved by permitting the modulating signal to vary the electrode voltage supplied to one of the elements of the vacuum tube. The result was the amplitude or maximum positive value of the sine-wave carrier signal was caused to vary instant by instant as the modulating signal level varied.
- A.
  
  Amplitude Modulation
- B.
  
  Vacuum-Tube Modulation
- C.
  
  Sine-Wave Modulation
- D.
  
  Carrier Modulation
22.

In Amplitude Modulation, we can show the output of the modulation that contain the following frequencies. Which of these is not an output?
- A.
  
  F(c)
- B.
  
  F(c) + F(m)
- C.
  
  F(c) - F(m)
- D.
  
  F(c) x F(m)
23.

In complex Amplitude Modulation, this sideband has the same shape and orientation as the band of modulating signal frequencies.
- A.
  
  Upper Sideband(USB)
- B.
  
  Lower Sideband(LSB)
- C.
  
  Frequency Sideband(FSB)
- D.
  
  Amplitude Sideband(ASB)
24.

In complex Analog Modulation, this sideband is the mirror image of the original modulating signal. This sideband is said to be inverted, since its shape is the reverse of the modulating signal.
- A.
  
  Lower Sideband(LSB)
- B.
  
  Upper Sideband(USB)
- C.
  
  Frequency Sideband(FSB)
- D.
  
  Amplitude Sideband(ASB)
25.

We can express the 6-to-1 improvement of SSBSC over DSBSC as __ decibels (dB) of improvement.
- A.
  
  8
- B.
  
  6
- C.
  
  4
- D.
  
  2