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Amplitude Modulation Essay

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Amplitude modulation or AM as it is often called, is a form of modulation used for radio transmissions for broadcasting and two way radio communication applications. Although one of the earliest used forms of modulation it is still in widespread use today. The first amplitude modulated signal was transmitted in 1901 by a Canadian engineer named Reginald Fessenden. He took a continuous spark transmission and placed a carbon microphone in the antenna lead. The sound waves impacting on the microphone varied its resistance and in turn this varied the intensity of the transmission. Although very crude, signals were audible over a distance of a few hundred metres, although there was a rasping sound caused by the spark. With the introduction of …show more content…

The resistor is used to enable the capacitor to discharge. If it were not there and no other load was present, then the charge on the capacitor would not leak away, and the circuit would reach a peak and remain there. Advantages of Amplitude Modulation, AM There are several advantages of amplitude modulation, and some of these reasons have meant that it is still in widespread use today: * It is simple to implement * it can be demodulated using a circuit consisting of very few components * AM receivers are very cheap as no specialised components are needed. Disadvantages of amplitude modulation Amplitude modulation is a very basic form of modulation, and although its simplicity is one of its major advantages, other more sophisticated systems provide a number of advantages. Accordingly it is worth looking at some of the disadvantages of amplitude modulation. * It is not efficient in terms of its power usage * It is not efficient in terms of its use of bandwidth, requiring a bandwidth equal to twice that of the highest audio frequency * It is prone to high levels of noise because most noise is amplitude based and obviously AM detectors are sensitive to it. Summary AM has advantages of simplicity, but it is not the most efficient mode to use, both in terms of the amount of space or spectrum it takes up, and the way in which it uses the power that is transmitted. This is the reason why it is not widely used these days both for

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