signalemitter

Signal emitter (signalemitter) is a general term for a source that generates a signal, used in both hardware and software contexts. A signal emitter can be a physical device that outputs an electrical, optical, or acoustic signal, or a software component that dispatches events to listeners. Emitted signals may be analog or digital and are commonly described by attributes such as amplitude, frequency, waveform, or event type and payload. The term emphasizes the active role of producing a signal rather than merely transmitting or processing it.

In electronics, common signal emitters include oscillators, function or signal generators, transmitters, microphones, LEDs, and radar or sonar beacons. They convert energy from a power source into a time-varying output. Important characteristics include waveform fidelity, spectral content, output impedance, and compatibility with the load. In some contexts, the standalone term emitter relates to transistor terminology where the emitter is a terminal that injects carriers, but this usage is distinct from a standalone signal source.

In software engineering, a signal emitter is an object or component that fires signals or events to registered listeners. This pattern underpins event-driven programming and is realized in various forms such as Qt's signals and slots, Node.js's EventEmitter, or Python event systems. Key concerns include decoupling between emitter and listeners, thread safety, and lifecycle management to avoid memory leaks.

Use cases include user interfaces, data acquisition, simulations, testing, and inter-process communication. When designing a signal emitter, practitioners specify the signal schema, decide between synchronous or asynchronous emission, and consider performance and reliability requirements.