FIELD: physics, navigation.
SUBSTANCE: invention relates to radar systems which are part of systems for active protection of the Earth from approaching natural and manmade objects. The apparatus includes a ground-based radar station with four receiving antennae and one transmitting antenna, two phase detectors, four information display units, a shift register and an asteroid velocity computing unit. The transmitting unit, which is mounted at the centre of a circle, emits a sawtooth chirp signal. Signals reflected by an asteroid are received by the receiving antennae arranged uniformly along the circle. Motion parameters of the asteroid are determined from detection times and frequencies of difference signals received and generated in the receiving antennae using said radar means.
EFFECT: wider range of radar systems for active protection of the Earth.
