AMPLITUDE MODULATION -(next part-1)

Firstly, let's have a look at what radio transmission is really all about.  It’s fine to have a microphone  to speak into and expect to be  heard somewhere  else in the world, however what are the  real  principles involved. This does not apply just to amplitude modulation but to all types of modulation.
Modulation - in radio communications means combining signals, one of which is  normally the  information we want to transmit  (which is usually  a  low  frequency  such  as  audio  orvoice),  with  a  radio frequency
              Radio communication uses the ability of an electromagnetic wave (or if you like electromagnetic energy) to transfer information from one point to another.It is very easy to create anelectromagnetic wave, send this wave to an antenna, and have this wave propagate over a long distance at the speed of light.It's another matter to have the electromagnetic wave contain useful information such as voice, or some other form of intelligence, which after all is the main objective of radio communication.

Remember that electromagnetic radiation takes many forms.  Light is electromagnetic radiation.The infrared  signal from your TV  remote control is electromagnetic radiation.The heat given off by a bar radiator is  electromagnetic radiation.The whole secret of radio
communication  is to place information  onto the signal,  to convey intelligence or a message from one point to another. ............