# Chapter 4: Amplitude Modulation Transmission - Review Notes

Reviewer and summary notes of the important concepts and formulas in Chapter 4 of the book "Introduction to Electronics Communications" by Wayne Tomasi.

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.

 CHAPTER 4 AMPLITUDE MODULATION TRANSMISSION
 Items Definitions Terms 1 The process of impressing low-frequency information signals onto a high-frequency carrier signal. Modulation 2 The reverse process of modulation where the received signals are transformed back to their original form. Demodulation 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 4 Frequencies that are high enough to be efficiently radiated by the antenna and propagated through free space. Radio Frequencies 5 The modulated output waveform from an AM modulator is? AM Envelope 6 Sometimes called conventional AM or simply AM. AM DSBFC 7 The band of frequencies between fc – fm (max) and fc. Lower Sideband 8 Any frequency within the lower sideband is called. Lower Side Frequency 9 The band of frequencies between fc and fc + fm(max) Upper Sideband 10 Any frequency within the upper sideband is called? Upper Side Frequency 11 The term used to describe the amount of amplitude change (modulation) present in an AM waveform signal. Coefficient of Modulation 12 The coefficient of modulation stated as a percentage. Percent Modulation 13 The maximum percent modulation that can be imposed without causing excessive distortion. 100% 14 The _______ in a transmitter where modulation occurs determines whether the circuit is a low or a high-level transmitter. Location 15 The modulation takes place prior to the output element of the final stage of the transmitter. Low-Level Modulation 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 17 The amplitude of the output signal depends on the amplitude of the input carrier and the voltage gain of the amplifier. Emitter Modulation 18 A class C modulator capable of nonlinear mixing and the modulating signal is applied directly to the collector. Collector Modulator 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 20 Are used for observing the modulation characteristics of AM transmitters. Trapezoidal Pattern 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 22 Complex waveforms comprised of two or more frequencies. Nonsinusoidal Signals 23 Are complex waves made up of two or more harmonically related sine waves and include square, rectangular, and triangular waves. Complex Repetitive Waveforms 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 90Âº out of phase with each other. Quadrature Amplitude Modulation ( QAM )

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