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[[File:Radio transmission waves(AM and FM).gif|thumbnail|The Audio Signal (top) is transmitted on a carrier wave by modifying the [[amplitude]] (middle) or [[frequency]] (bottom)]]

[[File:Radio transmission waves(AM and FM).gif|thumbnail|The Audio Signal (top) is transmitted on a carrier wave by modifying the [[amplitude]] (middle) or [[frequency]] (bottom)]]

'''Amplitude modulation''' (AM) is one of the two ways information is transmitted and received wirelessly using [[electromagnetic radiation]].  To transmit data or [[analog]] audio, a constant [[electromagnetic]] wave (carrier wave) is first produced.  Then the [[amplitude]] of this wave is modified in a specific pattern which may be translated back into audio or other data at the receiving end.

'''Amplitude modulation''' (AM) is one of several ways information is transmitted and received wirelessly using [[electromagnetic radiation]].  To transmit data or [[analog]] audio, a constant [[electromagnetic]] wave (carrier wave) is first produced.  Then the [[amplitude]] of this wave is modified in a specific pattern which may be translated back into audio or other data at the receiving end.

Amplitude modulated signals tent to travel line-of-sight from the source.  They also can be interfered with by lightning<ref>http://stormhighway.com/sferics.php</ref>.  For these reasons as well as others, [[frequency modulation]] is sometimes a preferred method of communication.

Amplitude modulated signals tend to travel line-of-sight from the source.  They also can be interfered with by lightning<ref>http://stormhighway.com/sferics.php</ref>.  For these reasons as well as others, [[frequency modulation]] is sometimes a preferred method of communication.  Another form of modulation, phase modulation, conveys information by instantaneous changes in the carrier wave's phase, rather than amplitude or frequency.  Phase modulation is the basis of many digital communications standards, such as [[WiFi]].

==References==

==References==

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