Amplitude modulation and demodulation electrical and computer. Once a signal has been modulated, information is retrieved through a demodulation process. As part of the modulation practices we simulated this am modulator circuit to test the effects of the modulation quotient in the signal we plan to transfer. Matlab code for amplitude modulation am file exchange. Change the amplitude of fg1 to 2 v and capture the am signal and its spectrum, use a different file. Amplitude modulation am is a process by which the wave signal is transmitted by. The measurement and definition of amplitude modulations. Typically the modulation depth is the amplitude modulation index expressed as a percentage.
In this code, it is considered the default value of ma equal to 1 for hundred percent modulation. Am modulators free download as powerpoint presentation. Amplitude modulation early radio ee 442 spring semester. The modulation index is defined as the ratio of the amplitude of the modulating signal to. Additive synthesis, amplitude modulation and frequency. The second is to investigate classical analog amplitude modulation and the envelope detector.
The code for amplitude modulation am with control of modulation index ma has been developed using matlab according to conventional theory. Here, we will implement the dsbam baseband modulator and demodulator using a music file as a source. Amplitude modulation definition, types, solved examples byjus. The maximum power efficiency of an am modulator is. Three modelling approaches to sound design, by e r miranda pdf file. Measuring the modulationindex for the single tonecase. You can publish your book online for free in a few minutes. Taking the ratio of these two equations and solving for gives the following formula for easily computing the modulation index from a display of the modulated signal. This experiment examines the characteristics of the amplitude modulation am. Amplitude modulation is mostly used in the form of electronic communication. Amplitude modulation index an overview sciencedirect topics. Pdf the effect of amplitude modulation index and frequency. We use cookies to help provide and enhance our service and tailor content and ads. In this modulator the amplitude of a carrier is varied in accordance with instantaneous value of message signal.
Am modulator is one which is used for superimposing a low frequency signal on a high frequency carrier signal. The modulation index m of an am signal is defined as m. The amplitude modulation am modulation depth figure is complementary to the modulation index. In the particular case when the message signal is a sinusoid of frequency fx. The amplitude modulation am modulation index can be defined as the ratio of the peak value of the message signal to the amplitude.
When expressed as a percentage it is the same as the depth of modulation. Amplitude modulation consists encoding information onto a carrier signal by varying the. This principle is at the heart of amplitude modulation. View the article online for updates and enhancements.
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