Abstract: A system for protecting sensitive zones includes detection bases disposed in such a way that each base performs the monitoring of a part of the limit of the protected zone. To each base n is allocated a frequency channel of width B? centered on a frequency Fn. Each base comprises a plurality of UHF radars emitting pulses of spectral width B, with a high repetition frequency Fr. Each radar processes a fraction b0 of the global Doppler band b1 concerned. The emission frequencies of the various radars constituting one and the same base are defined in such a way that the gap between the emission frequency Fi of a radar of the base and the frequency Fn is less than the repetition frequency Fr and that the gap between the emission frequencies Fi and Fj of two radars of one and the same base is greater than (b1+b0)/2.

Abstract: The present invention relates to a method enabling precise determination of the elevation of a projectile following a ballistic trajectory by use of a conventional Doppler surveillance radar. The method includes calculating first the estimate {circumflex over (?)}? of the value of the radial component ?? of the acceleration of the projectile from the quantities {dot over (d)} and {umlaut over (d)}, respectively representing the first derivative and the second derivative with respect to time of the Doppler velocity d of the projectile, then calculating the estimate {circumflex over (V)} of the speed V of the projectile from d, {dot over (d)} and {circumflex over (?)}?, and finally calculating the estimate Ê of its angle of elevation E from d and {circumflex over (V)}. The method according to the invention may apply to the protection of sensitive areas against the firing of ballistic projectiles.

Abstract: A system for protecting sensitive zones includes detection bases disposed in such a way that each base performs the monitoring of a part of the limit of the protected zone. To each base n is allocated a frequency channel of width B? centred on a frequency Fn. Each base comprises a plurality of UHF radars emitting pulses of spectral width B, with a high repetition frequency Fr. Each radar processes a fraction b0 of the global Doppler band b1 concerned. The emission frequencies of the various radars constituting one and the same base are defined in such a way that the gap between the emission frequency Fi of a radar of the base and the frequency Fn is less than the repetition frequency Fr and that the gap between the emission frequencies Fi and Fj of two radars of one and the same base is greater than (b1+b0)/2.