Gleichsignal

Gleichsignal is a term used in German-language signal processing to denote a signal that does not vary with time. In its most common interpretation, a Gleichsignal is a direct-current (DC) component or constant baseline contained in a signal, as opposed to a time-varying or alternating signal (Wechselsignal). While not a formal technical standard, the concept is widely used in engineering texts to describe stationary, non-oscillatory content.

Characteristics include constant amplitude or level, and a spectrum dominated by the zero-frequency (0 Hz) component. In practice, a Gleichsignal may represent sensor bias, offset, or a deliberately injected reference. It can arise from a steady source such as a battery, a bias circuit, or the average value of a fluctuating signal when its positive and negative variations cancel out over time.

Applications and implications: DC components must be handled carefully in many systems. Some circuits use DC coupling to preserve the Gleichsignal, while others remove it with high-pass filtering to avoid saturation or distortion. In instrumentation, measuring the DC level helps determine offsets, drifts, and baseline stability. DC restoration circuits may reintroduce a wanted offset to maintain operating ranges in video and analog electronics.

Measurement and challenges: Detecting a Gleichsignal requires DC-coupled instrumentation and stable reference grounds. Real-world signals exhibit drift from temperature, aging, or noise, so the Gleichsignal is rarely perfectly constant. Understanding and controlling the Gleichsignal is essential for accurate calibration, bias management, and long-term reliability of electronic systems.