How is information encoded onto radio waves?

I understand that there are two ways to encode information onto a wave: frequency modulation and amplitude modulation. But my question is how do people do this?



If I have a song that I would like to encode so it can be heard through the radio, what actually happens to allow the information of the sound waves in the song to be encoded onto the frequency or amplitude of the radio wave?How is information encoded onto radio waves?Get to know about amplitude modulation. The song can be converted to an electrical form. The song looks like noise (but is not noise) with a lot of large peaks and so on. If the peak is +/-5V, the rms may be about 1V.With this form, add a dc of 15V. That makes this song ride on a dc. Then multiply by the carrier which could be a 1 MHz. Then you get AM waveform. the signal gets transmitted as wireless because of the high frequency.

In the Receiver, capture whatever you get from antenna, and filter it with a band pass filter with bandwidth of 20kHz. Then amplitude demodulation will get you back the electrical form of the song, the dc being removed by a coupling capacitor in the final audio amplifier..

In FM, the frequency of the carrier typically 88 MHz gets modulated in such a way that 5V peak will create a deviation of 50kHz in 88 MHz.How is information encoded onto radio waves?Very detailed article here:

http://en.wikipedia.org/wiki/Modulation