This is the summary notes of the important terms and concepts in Chapter 4 of the book "Electronic Communications System" by Wayne Tomasi. The notes are properly synchronized and concise for much better understanding of the book. Make sure to familiarize this review notes to increase the chance of passing the ECE Board Exam.
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CHAPTER 4 |
AMPLITUDE MODULATION TRANSMISSION |
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Items |
Definitions |
Terms |
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1 |
The process of impressing low-frequency information signals onto a high-frequency carrier signal. |
Modulation |
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2 |
The reverse process of modulation where the received signals are transformed back to their original form. |
Demodulation |
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3 |
The process of changing the amplitude of a relatively high frequency carrier signal in proportion with the instantaneous value of the modulating signal. |
Amplitude Modulation |
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4 |
Frequencies that are high enough to be efficiently radiated by the antenna and propagated through free space. |
Radio Frequencies |
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5 |
The modulated output waveform from an AM modulator is? |
AM Envelope |
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6 |
Sometimes called conventional AM or simply AM. |
AM DSBFC |
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7 |
The band of frequencies between fc – fm (max) and fc. |
Lower Sideband |
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8 |
Any frequency within the lower sideband is called. |
Lower Side Frequency |
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9 |
The band of frequencies between fc and fc + fm(max) |
Upper Sideband |
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10 |
Any frequency within the upper sideband is called? |
Upper Side Frequency |
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11 |
The term used to describe the amount of amplitude change (modulation) present in an AM waveform signal. |
Coefficient of Modulation |
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12 |
The coefficient of modulation stated as a percentage. |
Percent Modulation |
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13 |
The maximum percent modulation that can be imposed without causing excessive distortion. |
100% |
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14 |
The _______ in a transmitter where modulation occurs determines whether the circuit is a low or a high-level transmitter. |
Location |
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15 |
The modulation takes place prior to the output element of the final stage of the transmitter. |
Low-Level Modulation |
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16 |
The modulation takes place in the final element of the final stage where the carrier signal is at its maximum amplitude. |
High-Level Modulation |
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17 |
The amplitude of the output signal depends on the amplitude of the input carrier and the voltage gain of the amplifier. |
Emitter Modulation |
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18 |
A class C modulator capable of nonlinear mixing and the modulating signal is applied directly to the collector. |
Collector Modulator |
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19 |
Used to translate the low-frequency intelligence signals to radio-frequency signals that can be efficiently radiated from an antenna and propagated through free space. |
Up-converter |
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20 |
Are used for observing the modulation characteristics of AM transmitters. |
Trapezoidal Pattern |
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21 |
A form of amplitude distortion introduced when the positive and negative alternations in the AM modulated signal are not equal (nonsymmetrical modulation). |
Carrier Shift |
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22 |
Complex waveforms comprised of two or more frequencies. |
Nonsinusoidal Signals |
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23 |
Are complex waves made up of two or more harmonically related sine waves and include square, rectangular, and triangular waves. |
Complex Repetitive Waveforms |
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24 |
A form of AM where signals from two separate information sources modulate the same carrier frequency at the same time without interfering with each other. The information sources modulate the same carrier after it has been separated into two carrier signals that are 90º out of phase with each other. |
Quadrature Amplitude Modulation ( QAM ) |
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