METHOD OF THE HIGH ACCURACY RESOLVING RANGE/VELOCITY UNCERTAINTY FOR THE LASER SCANNER WITH LINEAR FM

摘要

The laser scanning system on basis of CO_(2) laser with continuous radiation with 10.6 (mu)m wavelength situated onboard of aircraft is considered. The system is intended for remote sensing of surface ahead of aircraft. Simultaneously distance image of observed scene has to be formed and vehicle own velocity has to be measured. The system operates in a mode of azimuthal one-line scanning across a trajectory of flight. For distance measurement linear-frequency modulation with pulse compression is used. Pulse compression is produced with dispersive acoustic delay line. Mathematical expressions are known that permit to resolve distance/speed uncertainty in this case. These expressions need two sensing of each element of a surface. However in reality scanning is carried out continuously, so two neighbor sensings is made on different elements of surface. Suggested method permit to increase noticeably the accuracy of vehicle own velocity measurement while permitting to measure distance to each element of surface in case of continuous scanning. For this purpose the fact is used, that value of the carrier own velocity is slowly varying function. So, averaging and extrapolation of the information is made line by line to increase accuracy of vehicle own velocity measurement. For each sensing, distance is calculated based on the extrapolated velocity value.