3D153 CDC Volume 1
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Radio Frequency Transmission Systems Journeyman Volume 1
- 1.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.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, pulse width, and pulse position
- C.
Amplitude, frequency, and phase
- D.
Analog, digital and shift keying
- 3.When the modulating signal and carrier signal are combined within a modulator, the output signal 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.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 .99 MHz
- B.
1.1 MHz, 1 MHz, and .9 MHz
- C.
1.11 MHz, 1 MHz, .99 MHz
- D.
1.111 MHz, 1 MHz, .999 MHz
- 5.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.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 modulating index.
- D.
Defined in terms of maximum amount of modulation.
- 7.The amount of effect or change that the 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.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.Reducing modulation to less than 100 percent gives
- A.
More total power
- B.
A reduction to carrier power
- C.
No reduction in carrier power
- D.
A reduction in carrier and sideband power
- 10.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.
Durectly proportional to the phase of the modulating signal
- 11.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.What is the formula to find the modulating index?
- A.
Deviation divided by frequency of modulation
- B.
Deviation times frequency of modulation
- C.
Sideband divided by carrier frequency
- D.
Sideband times carrier frequency
- 13.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.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.What is the first step in the pulse code modulation (PCM) process?
- A.
Discrete amplitudes are assigned to the sampling pulse
- B.
A binary code number is assigned to the smaple.
- C.
The quantizer limits the amplitude of the pulses.
- D.
The analog signal is band limited
- 16.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.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.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.
Synchcroniztion (SYNC) bit
- 19.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.What two error detection methods, when used together, are 98 percent effective in detecting errors?
- A.
Checksum and cyclic redundancy checkin
- B.
Longitudinal redundancy check and checksum
- C.
Cyclic redundancy check and vertical redundancy check
- D.
Vertical redundancy check and longitudinal redundancy check
- 21.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.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.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.What does an optical source do?
- A.
Terminates fiber optic cables
- B.
Converts electrical energy into optical energy
- C.
Extend the distance and to preserve signal integrity
- D.
Accepts optical signals and converts them into electrical signals
- 25.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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