Signalin

Signalin is a term used in electronics and signal processing to denote the input signal to a system or component. It may refer to a single physical source or to a set of inbound signals, such as a multichannel sensor array. The term is often used in diagrams and documentation to label the portion of the signal chain that originates outside the device under test.

In time domain, signalin is described by its waveform, amplitude, phase, and sampling rate when digitized. In the frequency domain, it has a spectrum that can be analyzed via transfer functions and filters. Signalin can be affected by noise, distortion, impedance, and cross-coupling, which engineers account for in design.

Applications: In control systems, signalin is the input to a controller or plant; in communications, it represents the incoming transmitted data prior to modulation and demodulation; in instrumentation, it includes sensor outputs that drive measurement systems.

Measurement and conditioning: Signalin is often conditioned through amplification, filtering, impedance matching, and analog-to-digital conversion to produce a usable digital or processed result. Signal integrity considerations focus on maintaining fidelity from signalin to the processed output.

Examples: a microphone output feeding an audio processor; a temperature sensor sending a voltage to a microcontroller; a photodiode signal entering a transimpedance amplifier.

See also: input signal, signal path, transfer function, signal integrity.