An analog signal is within the signal theory, a shape of a signal with a continuous and uninterrupted curve. An analog signal is described as a smooth function, and can be described, for example, the time course of a continual physical quantity, such as the sound pressure in the form of an analog audio signal therewith. The range of values of an analog signal is referred to as dynamic range.
In electronics, analog signals are usually rarely chosen in the form of an electrical voltage as electric current to represent the physical size. More generally, an analog signal can be understood as a frequency, phase, or from physical quantities such as brightness, temperature, or various mechanical quantities. For example, use a can Barometer deformation as a result of pressure, or at a record analog audio signals can be obtained on height differences of the individual grooves.
Unlike a digital signal comprises an analog signal to a variable and any nice trip and can theoretically infinite number of values in the dynamic range. In real physical quantities, the resolution is limited by disturbances such as noise or distortion. Therefore, once can not be undone added disturbances in an analog signal. When a digital signal interference in the signal can, so that they remain under certain limits, be compensated by thresholding partly due to the quantization.
In electronics implementing an electrical analog signal is in a usable in digital signal processing of the digital signal by analog-to- digital converters (ADC), the reverse direction is carried out by means of digital to analog converters ( DAC).