section_path: Methods
section_name: Methods
paragraph_text: Methods
  
  In a broadcast system, the central high-powered broadcast tower transmits a high-frequency electromagnetic wave to numerous receivers. The high-frequency wave sent by the tower is modulated with a signal containing visual or audio information. The receiver is then tuned so as to pick up the high-frequency wave and a demodulator is used to retrieve the signal containing the visual or audio information. The broadcast signal can be either analog (signal is varied continuously with respect to the information) or digital (information is encoded as a set of discrete values).
  
  Historically, there have been several methods used for broadcasting electronic media audio and video to the general public: