AMPLITUDE MODULATION TRANSMISSION (C4 Tomasi)

CHAPTER 4

AMPLITUDE MODULATION TRANSMISSION

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 90° out of phase with each other. Quadrature Amplitude Modulation ( QAM )