Posted on April 20, 2013
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FM has been the king of the airwaves since it’s discovery. Operating in the range of 87.5MHz to 108MHz, FM radio offers a much better sound quality than AM, but it can’t reach the same distances. Although much more simple, AM radio can reach vast distances due to the nature of it’s modulation.
AM radios operate between 520kHz to 1710kHz in the United States. This carrier frequency differs in other parts of the world, but it’s effective range is much the same. What gives AM radio a distinct advantage over FM radio is its ability to bounce off of the upper atmosphere. Although it suffers from more noise and interference, AM broadcasts can be heard from vast distances making it an excellent way to communicate news quickly.
Amplitude modulation is much more simple than FM in that it changes the amplitude of the signal instead of the frequency. FM radio modulates the frequency that is transmitted while keeping the amplitude of the signal the same. With AM, the amplitude is modulated only when useful sound is transmitted. When affected, the amplitude will increase or decrease to produce the transmitted sound. Otherwise, an AM signal will sound like static until information is sent.Related Article : Re: Need for a signal generator