Sisendsignaalia

Sisendsignaalia is the signal that is applied to a system, device or process for processing, measurement, or transmission. It is distinguished from the output signal and from signals that exist inside the system. In Estonian technical usage, sisendsignaalia refers to the input signal entering a subsystem; the corresponding output is called väljundsignaal.

In electronics and signal processing, the input signal is usually denoted x(t) in the time domain or X(f) in the frequency domain. Its characteristics include amplitude, frequency content, phase, and any constant offset. The way the signal is supplied matters: source impedance and the device’s input impedance influence loading, distortion, and bandwidth. Signals may be fed through coupling elements (AC or DC), and the level may be adjusted by amplifiers or attenuators.

In a linear time-invariant system, the input and output are related by a transfer function H; the output y(t) equals the convolution x(t) * h(t). This relationship describes how the system shapes or responds to the incoming signal across time or frequency.

Applications span various fields: in audio, the input is a microphone signal; in instrumentation, a sensor signal; in control systems, a reference input; and in communications, the modulated baseband or RF signal.

Practical considerations include noise, distortion, saturation, dynamic range, and anti-aliasing for sampling. Proper impedance matching and signal conditioning ensure faithful reproduction of the input, and the overall system performance is closely tied to the quality of the sisendsignaalia.