| 1. |
____________ is the ability to impress intelligence upon a transmission medium, such as radio waves. |
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Modulation |
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Medium |
| 2. |
The rate at which the vector rotates determines the FREQUENCY of the sine wave that is generated; that is, the faster the vector rotates, the more cycles completed in a given time period. |
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True |
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False |
| 3. |
The process of combining two or more frequencies in non-linear impedance results in the production of new frequencies. This process is referred to as______________. |
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Heterodyning |
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Demodulation |
| 4. |
Two conditions must be met in a circuit for heterodyning to occur. First, at least two different frequencies must be applied to the circuit. Second, these signals must be applied to non-linear impedance. |
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True |
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False |
| 5. |
Amplitude modulation refers to any method of varying the amplitude of an electromagnetic carrier frequency in accordance with the intelligence to be transmitted by the carrier. |
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True |
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False |
| 6. |
The “on-off” KEYING of a ______________carrier frequency was the principal method of modulating a carrier in the early days of electrical communications. |
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Continuous wave |
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Development |
| 7. |
When greater frequency stability is required, the oscillator should be keyed, but should remain in continuous operation; other transmitter circuits may be keyed |
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True |
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False |
| 8. |
The categories of cw transmitters are as follows: |
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Master oscillator power amplifier (mopa) transmitters, |
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Multistage, high-power transmitters,
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High- and very-high frequency transmitters |
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All of the above |
| 9. |
The main advantage of a mopa transmitter is that the power-amplifier stage isolates the oscillator from the antenna. This prevents changes in antenna-to-ground capacitance from affecting the oscillator frequency. |
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True |
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False |
| 10. |
A______________ is an energy converter that changes sound energy into electrical energy. |
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Microphone |
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Diaphragm |
| 11. |
The sensitivity or efficiency of a microphone is usually expressed in terms of the electrical power level, which the microphone delivers to a matched-impedance load compared to the sound level being converted. |
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True |
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False |
| 12. |
An AM transmitter can be divided into major sections according to the frequencies at which they operate: |
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Radio frequency (rf) unit |
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Audio frequency (af) unit |
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a & b |
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None of the above |
| 13. |
What does FCC stand for? |
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Federal Communications Commission |
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Federal Communication Council |
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Federal Communications and Connections |
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None of the above |
| 14. |
To measure degrees of modulation less than 100 percent, you can use a MODULATION FACTOR (M) to indicate the relative magnitudes of the rf carrier and the audio-modulating signal. Numerically, the modulation factor is:
(Refer Pg 1-48) |
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 |
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What does Em stand for in the above equation? |
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RMS value of the modulation voltage |
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Amplitude |
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Frequency |
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None of the above |
| 15. |
Plate modulation permits the transmitter to operate with high efficiency. It is the simplest of the modulators available and is also the easiest to adjust for proper operation. |
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True |
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False |
| 16. |
_______________ is modulation produced in the plate circuit of the last radio stage of the system. |
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High-Level Modulation |
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Low-Level Modulation |
| 17. |
The modulation index as a formula is shown below: |
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| What does ∆f stand for? |
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Frequency deviation |
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Modulation frequency |
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Modulation factor |
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None of the above |
| 18. |
In frequency modulation (fm) the instantaneous frequency of the radio frequency wave is varied in accordance with the modulating signal; the amplitude of the radio-frequency wave is kept constant. |
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True |
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False |
| 19. |
_____________________ is modulation in which we allow oscillations to occur for a given period of time only during selected intervals. |
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Pulse modulation |
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Phase Shift Keying |
| 20. |
Pulse Code Modulation is a method of pulse modulation in which the modulating wave is used to frequency modulate a pulse-generating circuit. |
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True |
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False |
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