WE have AMA and FM... no other frequency modulaton.

Keeping it SIMPLISTIC... (someone could write an explaination that takes a CD to hold all the information...)

PPM and PCM are the signal encoding sent by the modulation. Its kind of like... do you want to send a digital computer signal or just send the same music in the form of the common AM radio waves. you can do either with AM or FM radio. (thats a simplistic explaination of the difference between AM radio and some early AM wireless networks...)

FM does inherantly have some improved interference rejection simply because the radio is chcking a "range" of frequencys for changes in a constant power level but varying the frequency. AM varies the power of the radi wave transmitted. and that closely resembles the noise generated by power lines. (thats basicly why AM radios go nuts under the high tension power lines... but FM you continue to hear your music.)


PPM - Pulse Proportional Modulation. if you have the correct type oscilliscope... you can LOOK at the signal and you will see the signal pattern and you can SEE the stick positions.

PCM - Pulse Code Modultaion. You have a seeries of digital codes being sent... the signal would look the same if you were sending a repeating binary computer code. just 1's and zeros. You can't see the stick positions unless you can decipher the code in your head.