ABSTRACT
Modulation is a technical term for changing. In amplitude modulation, the authors change the power of the transmitted wave in order to carry information. When there is no program, the standard amplitude modulated (AM) transmitter produces a constant "carrier" wave. With modulation this wave is increased or decreased in keeping with the positive and negative voltage in the program source. In the early 1970s, solid state devices had become commonplace enough that they were starting to make inroads into broadcast transmitters, albeit mostly at lower power levels in audio broadcasting, the audio program changes one or more of the four parts of the transmitter in accordance with the audio amplitude. Morse transmission, which is the simplest form of AM as well as the earliest form of digital communication, changes the amplitude between zero and full output, usually by the switch between the power source and the Direct current to radiofrequency conversion stage.
