Abstract: In an observation device according to the invention, it is possible to coordinate a multiplicity of functions with the device by using and exchanging optical modules. By means of existing optical components in the observation device, transmitted and/or received beams of the modules can be reflected in and/or reflected out. For example, field glasses, binoculars and measuring glassed can be equipped according to the invention with modules. The modules can be produced for special purposes, can be carried in particular as convenient units and can be inserted into the device and removed therefrom an can be exchanged. An optical module may be, for example, in the form of a camera, graphic display or IR laser. The modular multifunctional observation device according to the invention can be designed as a compact and light device by using optical components already present in the “basic system.

Abstract: For an observer equipped with a first azimuth data source responsive to a magnetic field to deliver first azimuth data, such as a compass, and with a second azimuth data source delivering second azimuth data and which is independent of magnetic fields, such as a gyroscope. The azimuth is determined by: analyzing the first and second azimuth data to determine whether a magnetic disturbance is present, and determining azimuth selectively on the basis of: the first azimuth data, the second azimuth data, or a combination of the first and second azimuth data, as a function of the result of the comparing step. In an embodiment, the choices of azimuth data source and events such as magnetic disturbances, sensor updates, types of trajectory deduced, are stored as a history sequence over successive time windows, by analogy with a DNA sequence, and is exploited for optimizing azimuth or navigation results.