Abstract: Society becomes more developed now, science and technology in the
update, in which signal and analog circuits often used in modulation and
demodulation, and AM modulation and demodulation is the most basic, is also
frequently used. To participate in the identification of such artificial
methods, the ruling includes subjective factors, will vary from person to
person, can identify the type of modulation is very limited. Automatic
modulation recognition technology can be overcome not only to participate
in recognition of artificial difficulties, and the center frequency and
bandwidth of the estimation error, adjacent channel crosstalk, noise and
interference factors such as the decline of effect is relatively robust.
Using AM modulation and demodulation circuit which can achieve a lot of
features, creating a lot of useful and affordable electronic products, in
order to facilitate our lives. Used in our daily lives is the use of AM
radio modulation, but also in the field of military and civilian research
topics are very important.
The main content of this paper is to understand the mathematical
model of the AM signal and the modulation and the demodulation method.
Demodulation different methods in different circumstances of the
demodulation signal to noise ratio the results of methods that better, to
make the comparison. Requirement is more than double the sound and the AM
signal modulation and demodulation. AM modulation first study of its
function and in real life use. AM demodulation followed by research, as
well as some related knowledge, as well as through its use of
communications more in-depth understanding of it. AM signal from the tone
of the mathematical model and the modulation and demodulation methods, the
two-tone AM signal to draw a mathematical model and the block diagram of
modulation and demodulation and modulation and demodulation waveforms.
MATLAB programming language to use to achieve the two-tone AM signal
modulation and demodulation, given the different circumstances of the
demodulation signal to noise ratio compared the results. Keyword: AM
signal, Modulation, rate of work, MATLAB
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