The altimeter function is very simple served “just” to tell the pilot to fly height is exactly. Much more complex as it gets this device and return a given height based on different parameters. Altitude level is based on a certain point where a static pressure is exerted.
One of their specific names is the pressure altimeter established and measured pressures. To summarize this instrument focuses on static pressure point and that point based on a given set height. And then transforms it into a measurement value and no pressure to show it to the pilot.
The altimeter is formed of a series of pieces called aeroidales capsules, which depending on their number greater accuracy is achieved in the functioning of the instrument itself. Is almost completely inside vacuum, to balance the pressure force to be held at sea level, a kind of spring placed inside two parts so that its expansion force open the capsule is placed. Thus two forces are available in one of the spring opposed to the capsule opens out and over the pressure of the atmosphere. With these two forces can determine the height.