The computerized radar-tracking ornithological system developed for MRL-5 meteorological radar enables to carry out automatic tracing of bird migration at any time. The algorithm of bird signals identification on the background of other signals is constructed due to the following principles: (1) The radar signal reflected by a bird changes its location in time because of movement. If, even within a short period of time, the bird moves without changing its direction, the coordinates of the radar echo central point form a straight line of continuous tracing as reflected at one angular location of the antenna. (2) This feature can be used for vector calculations (both direction and speed) reflecting movement of the bird flock or of a separate bird. The peculiarity of MRL-5 is that it is equipped with a polarizing device enabling on the 3.2 cm wavelength to change polarization of pulse-to-pulse radiation and, correspondingly, to accept the signal of the same polarization as that of the radiated one, together with its depolarization components. The present report shows that the depolarization degree of the signal as reflected by birds is approximately that of 7÷10 dB. Calculated and experimental data indicate that the MRL-5 radar characteristics at the height of 270 m above the sea level provide identification of a single bird of the albatross size flying 700 m high at the distance of 100 km. Bird like sparrow could be detected at the flight height exceeding 100 m, 15 km (in flock - up to 30 km) away from the radar location. The narrow symmetrical diagram of the antenna direction is 0.5 degrees for λ=3 cm and 1.5 degrees for λ=10 cm. This enables to determine the flight height of a single bird or of a flock within the radar-tracking space with high precision.
展开▼
