Chapter 1. Introductory Topics
1. Which part of the sinewave expression cannot be varied in accordance with the low-frequency intelligence to create a modulated signal?
a. Phase
b. Frequency
c. Time
d. Amplitude
2. Communication systems are most often categorized by what characteristic?
a. Modulation frequency
b. Carrier frequency
c. Transmission distance
d. Information transmitted
3 Voltage gain in decibels is
| a. 10 ln  |
| b. 10 log |
| c. 20 ln |
| d. 20 log |
4 Which expression indicates a measurement using a 1-W reference
a. dBm(1)
b. dB1
c. dBW
d. dB(W)
5 An amplifier operating over a 2-Mhz bandwidth has a 75 input resistance. If it is operating at 22° C and
has a voltage gain of 300, the noise produced at the output of this amplifier would be approximately
| a.  |
| b.  |
| c.  |
| d.  |
6 Which of the following is not an example of external noise
a. Fluorescent light
b. Solar emission
c. Resistor noise
d. Lightning
7 An amplifier's output signal has 25 mV p-p of desired signal mixed in with 45 V rms of undesired noise. The load impedance is 50 . What is the amplifier's output S/N level in dB?
a. 22.9 dB
b. 54.9 dB
c. 45.9 dB
d. 51.9 dB
8 Why does a 5-kHz square wave require a greater bandwidth than a 2-kHz sinewave?
a. The square wave has a larger frequency than the sinewave.
b. The square wave has an infinite number of harmonics, whereas the sinewave has only one.
c. The square wave is much easier to cover by noise.
d. The square wave must also include an offset (dc) voltage, whereas the sinewave does not.
9 The relationship between information and bandwidth is called
a. Information theory
b. Fourier analysis
c. FFT
d. Hartley's law
10 Aliasing can be defined as errors occurring when
a. The input frequency exceeds the sample rate.
b. The bandwidth is less than the input frequency.
c. The type of modulation has been incorrectly identified.
d. The sampling signal has been incorrectly identified.
11 Which of the following does not hold true for a parallel resonant circuit?
a. At the resonant frequency the impedance of the circuit is a minimum.
b. If Q>10, the resonant frequency is the same as it would be if it were a series.
c. It is commonly referred to as a tank circuit.
d. At the resonant frequency, the circuit draws minimum current from the constant-voltage source.
12 The oscillator design that uses a third capacitor in the tank circuit for swamping out the effect of the
transistor's internal capacitances is the
a. Hartley design
b. Clapp design
c. Colpitts design
d. Crystal design
13 The ability of a crystal to oscillate at its resonant frequency is due to
a. The flywheel effect
b. Barkhausen criteria
c. The piezoelectric effect
d. Frequency synthesis
14 The Barkhausen criteria has to do with
a. Receiver noise
b. Fourier analysis
c. Oscillation
d. Troubleshooting
15 Which of the following can be called a troubleshooting plan?
a. Symptoms as clues to faulty stages
b. Signal tracing and signal injection
c. Voltage and resistance measure
d. Substitution
e. All the aboveAnswers:
| C |
| B |
| D |
| C |
| D |
| C |
| C |
| B |
| D |
| A |
| A |
| B |
| C |
| C |
| E |
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