Radio surveillance spectrum - Goniometry and Localization

Communications have become essential, both in the civilian sphere (the political, economic and social functioning of our society, which is increasingly based on the transmission of information between individuals, economic players, managers and regulatory bodies), and in the military sphere, for the conduct of forces and control of the theater of operations.

Rational and efficient use of the spectrum for civil applications, and verification of the correct application of regulations, has always required signal direction-finding and radiolocation functions for communications transmitters, integrated into spectrum monitoring systems. Direction-finding is therefore mainly linked to the following needs:

• locate interfering transmitters or intruders;

  help diagnose interference situations where necessary;

  more reliable and accurate monitoring of spectrum use, field strength measurements and verification of legitimate transmitters' compliance with local regulations.

In the military field, the need for theater forces to be able to warn and react to possible threats has always called for highly automated direction-finding functions, combined, where appropriate, with functions for identifying intercepted signals [TE 6 893] .

Integrated into tactical devices deployed in theaters, or into the information systems of forces on operations, direction finders are essential sensors for warning and self-protection modes. Direction-finding and radiolocation also make a major contribution to signals intelligence, and are therefore present in many land, sea and airborne sensors and sensor systems.

Advances in digital transmission technologies, the volumes transmitted, the variability of waveforms and radio access protocols have accelerated sharply over the last twenty years, increasing not only the heterogeneity of signals, but also the density of transmitters, the complexity and in-stationarity of propagation environments; and finally, the need for sensitivity, resistance to interference and jamming in direction-finders. In addition, the tacticality, speed and automation of direction-finding systems are crucial to their operational performance.

However, in response to this increase in complexity and the corresponding renewal of operational requirements, direction-finding equipment has also benefited from recent technological...