a. co-channel interference b. adjacent channel interference c. splatter d. overmodulation 77. A pre-emphasis is usually a ________.
a. high-pass filter b. band-stop filter c. low-pass filter d. bandpass filter 78. Frequency modulation transmitters are more efficient because their power is increased by what type of amplifier? a. class A b. class B c. class C d. all of the above 79. Noise interferes mainly with modulating signals that are a. sinusoidal b. non-sinusoidal c. low frequencies d. high frequencies 80. A de-emphasis is usually a _________. a. high pass filter b. band-stop filter c. low-pass filter d. bandpass filter 81. A pre-emphasis is a __________. a. integrator b. differentiator c. either integrator or differentiator d. neither integrator or differentiator
82. A de-emphasis is a _____________. a. integrator b. differentiator c. either integrator or differentiator d. neither integrator or differentiator 83. Pre-emphasis circuit boost what modulating frequencies before modulation? a. high frequencies b. mid-range frequencies c. low frequencies d. all of the above 84. The primary disadvantage of direct PM a. relatively unstable LC oscillators must be used to produce carrier frequency which prohibits using crystal oscillators b. relatively high frequency deviations and modulation indices are easily obtained due to the fact that the oscillators are inherently unstable. c. crystal oscillators are inhrently stable and therefore more difficult for them to achieve high phase deviations and modulation indices d. carrier oscillator is isolated form the actual modulator circuit and therefore can be stable source. 85. It is an angle modulation in which the frequency of the carrier is deviated by the modulating signal a. direct PM b. PM c. indirect FM d. any of these 86. One of the following is a method of performing frequency up conversion a. heterodyning
b. amplification c. modulation d. none of these 87. A pre-emphasis circuit is a a. low-pass filter b. high-pass filter c. phase shifter d. bandpass filter 88. Pre emphasis is compensated for the receiver by a a. phase inverter b. bandpass filter c. high-pass filter d. low-pass filter 89. A circuit that compares the frequency of the noncrystal carrier oscillator to a crystal reference oscillator and then produces a correction voltage proportional to the difference between the two frequencies a. AFC b. squelch circuit c. AGC d. heterodyning circuit 90. A frequency selective device whose output voltage is proportional to the difference between the input frequency and its resonant frequency a. modulator b. squelch circuit c. frequency discriminator d. FM transmitters
91. Allows FM receiver to differentiate between two signals received with the same frequency but different amplitudes a. flywheel effect b. amplitude limiting c. noise immunity d. capture effect 92. If an FM transmitter employs one doubler, one tripler, and one quadrupler, what is the carrier frequency swing when the oscillator frequency swing is 2kHz?
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- Spring '13
- Thermodynamics, d., Edward Joseph D, Adrian A, Woodrow B. Pino