Informationssignal

An Informationssignal, or information signal, is a signal that conveys information, representing a message, data, or sensory measurements. In engineering practice it is distinguished from signals that do not carry meaningful content, such as synchronization or control signals, and from pure noise. Information signals can be analog or digital and may be transmitted in baseband or modulated to a higher frequency for transmission over a channel.

The information content of a signal is often analyzed statistically. In information theory, measures such as entropy and mutual information quantify the average amount of information carried per sample and the maximum reliable data rate under given channel conditions (channel capacity). Practically, signals are described as stochastic processes and may be characterized by their power spectrum, bandwidth, and sampling rate. The distinction between information signal and other signal components helps in evaluating efficiency and reliability of communications.

In communications systems the information signal is processed through a chain that includes source coding (compression), channel coding (error correction), modulation, transmission through a physical channel, demodulation, and decoding. Noise and distortion perturb the signal, so robust coding and adequate bandwidth are essential to recover the original information. The term also encompasses the concept that the signal carries content beyond its physical waveform, i.e., the message.

Examples include a voice waveform on a telephone line, a digital file transmitted over a network, or sensor readings from an Internet of Things device. In signal processing, the information signal is the component of interest that is extracted, analyzed, or reconstructed from measured data.