analog signal
1. A signal that has a continuous nature rather than a pulsed or discrete nature.
Note: Electrical or physical analogies, such as continuously varying voltages, frequencies, or phases, may be used as analog signals.
2. A nominally continuous electrical signal that varies in some direct correlation with another signal impressed on a transducer.
Note: For example, an analog signal may vary in frequency, phase, or amplitude in response to changes in physical phenomena, such as sound, light, heat, position, or pressure.