E8 - SIGNALS AND EMISSIONS [4 Exam Questions - 4 Groups] 45 Questions Flashcards
“What is the name of the process that shows that a square wave is made up of a sine wave plus all its odd harmonics?”
A. Fourier analysis
B. Vector analysis
C. Numerical analysis
D. Differential analysis
A. Fourier analysis
“Which of the following is a type of analog-to-digital conversion?”
A. Successive approximation
B. Harmonic regeneration
C. Level shifting
D. Phase reversal
A. Successive approximation
“What type of wave does a Fourier analysis show to be made up of sine waves of a given fundamental frequency plus all its harmonics?”
A. A sawtooth wave
B. A square wave
C. A sine wave
D. A cosine wave
A. A sawtooth wave
“What is “dither” with respect to analog-to-digital converters?”
A. An abnormal condition where the converter cannot settle on a value to represent the signal
B. A small amount of noise added to the input signal to allow more precise representation of a signal over time
C. An error caused by irregular quantization step size
D. A method of decimation by randomly skipping samples
B. A small amount of noise added to the input signal to allow more precise representation of a signal over time
“What of the following instruments would be the most accurate for measuring the RMS voltage of a complex waveform?”
A. A grid dip meter
B. A D’Arsonval meter
C. An absorption wave meter
D. A true-RMS calculating meter
D. A true-RMS calculating meter
“What is the approximate ratio of PEP-to-average power in a typical single-sideband phone signal?”
A. 2.5 to 1
B. 25 to 1
C. 1 to 1
D. 100 to 1
A. 2.5 to 1
“What determines the PEP-to-average power ratio of a single-sideband phone signal?”
A. The frequency of the modulating signal
B. Speech characteristics
C. The degree of carrier suppression
D. Amplifier gain
B. Speech characteristics
“Why would a direct or flash conversion analog-to-digital converter be useful for a software defined radio?”
A. Very low power consumption decreases frequency drift
B. Immunity to out-of-sequence coding reduces spurious responses
C. Very high speed allows digitizing high frequencies
D. All these choices are correct
C. Very high speed allows digitizing high frequencies
“How many different input levels can be encoded by an analog-to-digital converter with 8-bit resolution?”
A. 8
B. 8 multiplied by the gain of the input amplifier
C. 256 divided by the gain of the input amplifier
D. 256
D. 256
“What is the purpose of a low-pass filter used in conjunction with a digital-to-analog converter?”
A. Lower the input bandwidth to increase the effective resolution
B. Improve accuracy by removing out-of-sequence codes from the input
C. Remove harmonics from the output caused by the discrete analog levels generated
D. All these choices are correct
C. Remove harmonics from the output caused by the discrete analog levels generated
“Which of the following is a measure of the quality of an analog-to-digital converter?”
A. Total harmonic distortion
B. Peak envelope power
C. Reciprocal mixing
D. Power factor
A. Total harmonic distortion
“What is the modulation index of an FM signal?”
A. The ratio of frequency deviation to modulating signal frequency
B. The ratio of modulating signal amplitude to frequency deviation
C. The type of modulation used by the transmitter
D. The bandwidth of the transmitted signal divided by the modulating signal frequency
A. The ratio of frequency deviation to modulating signal frequency
“How does the modulation index of a phase-modulated emission vary with RF carrier frequency?”
A. It increases as the RF carrier frequency increases
B. It decreases as the RF carrier frequency increases
C. It varies with the square root of the RF carrier frequency
D. It does not depend on the RF carrier frequency
D. It does not depend on the RF carrier frequency
“What is the modulation index of an FM-phone signal having a maximum frequency deviation of 3000 Hz either side of the carrier frequency when the modulating frequency is 1000 Hz?”
A. 3
B. 0.3
C. 3000
D. 1000
A. 3
“What is the modulation index of an FM-phone signal having a maximum carrier deviation of plus or minus 6 kHz when modulated with a 2 kHz modulating frequency?”
A. 6000
B. 3
C. 2000
D. 1/3
B. 3
“What is the deviation ratio of an FM-phone signal having a maximum frequency swing of plus-or-minus 5 kHz when the maximum modulation frequency is 3 kHz?”
A. 60
B. 0.167
C. 0.6
D. 1.67
D. 1.67
“What is the deviation ratio of an FM-phone signal having a maximum frequency swing of plus or minus 7.5 kHz when the maximum modulation frequency is 3.5 kHz?”
A. 2.14
B. 0.214
C. 0.47
D. 47
A. 2.14
“Orthogonal Frequency Division Multiplexing is a technique used for which type of amateur communication?”
A. High-speed digital modes
B. Extremely low-power contacts
C. EME
D. OFDM signals are not allowed on amateur bands
A. High-speed digital modes