Rf 3D1X3 CDC Vol 1 Unit 1-4

64 Questions | By Brocj357 | Last updated: Jan 31, 2013 | Total Attempts: 53

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Unit 1-4 URE

Questions and Answers

1.

(001) What reason for modulation involves modulating low frequency signals for transmission over long distances?
- A.
  
  Spectrum conservation
- B.
  
  Channel allocation
- C.
  
  Ease of radiation
- D.
  
  Companding
2.

(001) What are the three general categories used to produce modulation in radio frequency (RF) transmission today?
- A.
  
  Binary amplitude shift keying, frequency shift keying, and phase shift keying
- B.
  
  Pulse amplitude, frequency, and phase
- C.
  
  Amplitude, frequency, and phase
- D.
  
  Analog, digital and shift keying
3.

(002) When the modulating signal and carrier signal are combined within a modulator, the output signals contains a/an
- A.
  
  Modulating signal, upper sideband, lower sideband
- B.
  
  Carrier, upper sideband, and lower sideband
- C.
  
  Upper sideband and modulating signal
- D.
  
  Carrier and modulating signal
4.

(002) If a carrier frequency of 1 MHz and a modulating tone of 10 kHz goes to the modulator, the output signal include
- A.
  
  1.01 MHz, 1 MHz, and 0.99 MHz
- B.
  
  1.1 MHz, 1 MHz, and 0.9 MHz
- C.
  
  1.11 MHz, 1 MHz, 0.99 MHz
- D.
  
  1.111 MHz, 1 MHz, 0.999 MHz
5.

(002) If the modulating audio signal is 10 kHz wide, what is the bandwidth of the transmitted amplitude modulated signal?
- A.
  
  5 kHz
- B.
  
  10 kHz
- C.
  
  15 kHz
- D.
  
  20 kHz
6.

(002) The bandwidth of an amplitude modulated signal is
- A.
  
  Two times the modulating signal
- B.
  
  The same as the modulating signal
- C.
  
  Determined by the modulation index
- D.
  
  Defined in terms of maximum amount of modulation
7.

(002) The amount of effect or change that intelligence has on the carrier in an amplitude modulated signal is expressed as the
- A.
  
  Percent of modulation
- B.
  
  Modulation index
- C.
  
  Bandwidth
- D.
  
  Deviation
8.

(002) Which statement concerning bandwidth is true?
- A.
  
  Overmodulating increases bandwidth due to the production of harmonics
- B.
  
  Undermodulating increases bandwidth due to the production of harmonics
- C.
  
  Overmodulating increases bandwidth due to the output's increased amplitude
- D.
  
  Undermodulating increases bandwidth due to the output's decreased amplitude
9.

(002) Reducing modulation to less than 100 percent gives
- A.
  
  More total power
- B.
  
  A reduction in carrier power
- C.
  
  No reduction in carrier power
- D.
  
  A reduction in carrier and sideband power
10.

(003) In frequency modulation (FM), the amount of oscillator frequency change is
- A.
  
  Inversely proportional to the amplitude of the modulating signal
- B.
  
  Directly proportional to the amplitude of the modulating signal
- C.
  
  Inversely proportional to the phase of the modulating signal
- D.
  
  Directly proportional to the phase of the modulating signal
11.

(003) In frequency modulation (FM), what is considered a significant sideband?
- A.
  
  Sidebands containing at least 1 percent of the total transmitted power
- B.
  
  Sidebands containing at least 3 percent of the total transmitted power
- C.
  
  Sidebands containing at least 10 percent of the total transmitted power
- D.
  
  Sidebands containing at least 0.1 percent of the total transmitted power
12.

(003) What is the formula to find the modulating index?
- A.
  
  Deviation divided by frequency of modulation
- B.
  
  Deviation times frequency of modulation
- C.
  
  Sideband divide by carrier frequency
- D.
  
  Sideband times carrier frequency
13.

(004) In phase modulation (PM), the carrier's
- A.
  
  Phase is shifted at the rate of the modulating signal
- B.
  
  Phase shifted with the phase of the modulating signal
- C.
  
  Amplitude is shifted at the rate of the modulating signal
- D.
  
  Amplitude is shifted with the phase of the modulating signal
14.

(004) What is the advantage of adding more phase shifts?
- A.
  
  Easier detection
- B.
  
  Smaller bit error rate
- C.
  
  Better signal-to-noise ratio
- D.
  
  Higher data rates within a given bandwidth
15.

(005) What is the first step in the pulse code modulation (PCM) process?
- A.
  
  Discrete amplitudes are assigned to the sampling pulses
- B.
  
  A binary code number is assigned to the sample
- C.
  
  The quantizer limits the amplitude of the pulses
- D.
  
  The analog signal is band-limited
16.

(005) What part of the pulse code modulation (PCM) process converts a continuous time signal into a discrete time signal?
- A.
  
  Sampling
- B.
  
  Rectifying
- C.
  
  Oscillating
- D.
  
  Band limiting
17.

(005) A type of pulse modulation (PM) that changes the amplitude of the pulse train to vary according to the amplitude of the input signal is called
- A.
  
  Pulse width modulation (PWM)
- B.
  
  Pulse position modulation
- C.
  
  Pulse duration modulation
- D.
  
  Pulse amplitude modulation
18.

(006) If an error should occur, what data transmission is lost in a synchronous transmission?
- A.
  
  One character
- B.
  
  Block of data
- C.
  
  A parity bit
- D.
  
  Synchronization (SYNC) bit
19.

(007) When using vertical redundancy check (VRC), what significance does the amount of ones have in a data bit pattern?
- A.
  
  Determines parity
- B.
  
  Determines transmission rate
- C.
  
  Determines whether transmission is in American Standard code for information Interchange (ASCII) format
- D.
  
  Determines whether transmission is synchronous or asynchronous
20.

(007) What two error detection methods, when used together, are 98 percent effective in detecting errors?
- A.
  
  Checksum and cyclic redundancy check
- B.
  
  Longitudinal redundancy check and checksum
- C.
  
  Cyclic redundancy check and vertical redundancy check
- D.
  
  Vertical redundancy check and longitudinal redundancy check
21.

(007) What error detection method adds stacked characters, divides it by 255, and disregards the answer except for the remainder?
- A.
  
  Checksum
- B.
  
  Block check character
- C.
  
  Cyclic redundancy check
- D.
  
  Vertical redundancy check
22.

(007) What error-correction technique sends a retransmittal request by the receiver to the sender if it finds an error in a received frame?
- A.
  
  Error-correcting code
- B.
  
  Forward error control
- C.
  
  Redundant data transfer
- D.
  
  Automatic retransmit on request
23.

(007) When using forward error control as a method of error correction, where does error correction take place?
- A.
  
  Receiving end
- B.
  
  In the oscillator
- C.
  
  Transmitting end
- D.
  
  In the primary buffers
24.

(008) What does an optical source do?
- A.
  
  Terminates fiber optics cable
- B.
  
  Converts electrical energy into optical energy
- C.
  
  Extends the distance and to preserve integrity
- D.
  
  Accepts optical signals and converts them into electrical signals
25.

(008) Light sources that are applicable to fiber optic waveguide are light-emitting diodes (LED) and
- A.
  
  Photo transistors
- B.
  
  Hybrid photodiodes
- C.
  
  Semiconductor laser diodes
- D.
  
  Integrated photodiode/preamplifiers