The information content of analog signal and digital signal shows that the analog signal adopts the amplitude of positive dialing, and the decreasing amplitude is in a continuous state, and the analog waveform will be recorded on the master tape, so the analog signal is a waveform diagram.

Analog signal refers to the information represented by a continuously changing physical quantity, whose amplitude, frequency or phase change continuously at any time. In a time interval, the characteristics representing the information amount are represented as arbitrary numerical signals at any time.