A signal while being transmitted has to go through different stages. First it is generated. After that its presence is sensed using different sensing devices. Next step is to 'condition' the signal. If the signal is weak, its amplified, and if it has noice a filter is used to remove the noise. A conditioned signal is now ready to be transmitted to the next stage. But the component on the next stage may not accept the signal as it is. The signal is converted to Analog or Digital format and then sent to the computation stage. The computation stage then evaluates the value of the signal and decides what must be done. It may give out a control signal to the output device to perform a necessary action. The output device may just be a display unit or it could be a mechanical component of the system that performs a physical action in response to the control signal received from the computation stage.