Rf 3D1X3 CDC Vol 1 Unit 1-4
Unit 1-4 URE
- 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
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