In relation to time this is a variable, e. g. a voltage or a current, having a parameter (amplitude, frequency, phase angle), allowing concrete information about the value sequence of another physical size. The corresponding parameter is called information parameter.
By means of a tachometer generator e. g. the speed of a mechanical shaft can be measured, this means it can be presented on the amplitude of the generator's output voltage. The amplitude of the output voltage is the information parameter permitting information about the time value sequence as defined by the determined signal definition. According to the available values, temporal availability and number of the information parameters there are different signal types.
For the automation technology
Analog signal,
Binary signal and
Digital signal are important.
