Introduction

Abstract

Our interaction with our natural and artificial environment is based on perception, transmission, storage and processing of signals of different kind. Through the eyes and ears we percieve optical (visual) and acoustical (audible) signals which are transformed into nerve signals to be transmitted, stored and processed in our neural network and brain. In reply, the brain generates other nerve signals which pass through the neural network and put our muscles into operation. In such a way we adapt ourselves to the environment or/and change (control) the environment. In technical information systems (which help us to solve the same tasks of adaptation to or transformation of the environment) we encounter electrical and radio-signals, optical and acoustical signals (including signals outside the boundaries of our perception), mechanical, pneumatic, hydraulic and many other signals.