What is modulation in radio communication?
Modulation is the process whereby some characteristic of a carrier wave is varied in accordance with a signal desired to be conveyed (ARRL handbook is a good resource for inquires of this type). The circuit responsible for performing this function is termed modulator. Naturally, there have been different modulation schemes developed and they fall into categories such as angle and pulse modulation.
working on radar and radios in my shop, we are at least requiered to know a basic understanding of modulation. i'll give you the brief summary of what AETC teaches my field.
AM - Amplitude Modulation
this is when the apmlitude of the signal and it's sidebands are varried by a certain percent. i believe that commerical radio is 80%.
FM - Frequency Modulation
this is when the carrier wave's freq is varried within a certain range. and i think that commerical radio is .05MHz
PM - Pulse Modulation
as far as i know, this isn't used in radio, but only in radar. the pulse's freq is modulated from a lower limit to a higher limit. it is used to determine distance. i'd say more about it, but i'm not sure what parts are classified.
A good starting point as well: http://answers.com/main/ntquery?s=modulation
Thank you, it was quite interesting!
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