Insignal

Insignal is a term used in signal processing and related engineering disciplines to denote the input signal of a system, subsystem, or processing block. It is not a formal standardized term with a universal definition, but an informal label that appears in technical documentation, schematics, and software models to distinguish the driving quantity from the system’s output.

In continuous-time and discrete-time models, the insignal is the quantity that enters a dynamic element. It is frequently represented as u(t) in continuous time or u[n] in discrete time, while the corresponding output is often written as y(t) or y[n]. The insignal can be an electrical voltage or current, an acoustic waveform, a sensor measurement, or any data stream that serves as the input to a processor.

In practice, insignal appears in block diagrams, transfer-function representations, and DSP pipelines. It is a placeholder name for the signal entering a processing block, and it may be named differently in various contexts (for example, input, u, or drive). In software implementations, the insignal is commonly provided as a data array or stream and fed into filters, modulators, or controllers.

Because insignal is not a universally standardized term, its precise meaning depends on context. Readers should refer to the surrounding material to determine what the insignal represents in a given model.

See also: input signal, output signal, transfer function, control theory, block diagram, signal processing, digital signal processing.