3D Laser Imaging Reconstruction of Scenes Using New Photometric Gaussian Beam Range Equation

In this article the problem of three-dimensional （3-D） reconstruction of scenes from terrestrial laser rangefinder data is processed, we present the simulations results of radiometric range function of the laser range finder imaging system for better optimization of maximum range detection with a given SNR （Signal-to-noise ratio）. The study proposes a new reformulation of the radiometric Gaussian beam range equation on the basis of the photodetector active area. The adjustment of the optical and geometrical characteristics of the laser range finder so defined can be used to minimize the signal span to avoid the saturation of the detector cell and improve the ranging measurements （accuracy and range） for a 3D imaging application.

Research on Asymmetric Fault Location of Wind Farm Collection System Based on Compressed Sensing

Aiming at the problem that most of the cables in the power collection systemof offshore wind farms are buried deep in the seabed,whichmakes it difficult to detect faults,this paper proposes a two-step fault location method based on compressed sensing and ranging equation.The first step is to determine the fault zone through compressed sensing,and improve the datameasurement,dictionary design and algorithmreconstruction:Firstly,the phase-locked loop trigonometric functionmethod is used to suppress the spike phenomenon when extracting the fault voltage,so that the extracted voltage valuewillnot have a large error due to the voltage fluctuation.Secondly,theλ-NIM dictionary is designed by using the node impedancematrix and the fault location coefficient to further reduce the influence of pseudo-fault points.Finally,the CoSaMP algorithmis improved with the generalized Jaccard coefficient to improve the reconstruction accuracy.The second step is to use the ranging equation to accurately locate the asymmetric fault of the wind farm collection system on the basis of determining the fault interval.The simulation results show that the proposedmethod ismore accurate than the compressedsensingmethod andimpedancemethod in fault section location and fault location accuracy,the relative error is reduced from 0.75%to 0.4%,and has a certain anti-noise ability.

Stealth performance evaluation of helicopter against airborne early warning radar considering trimming control

Airborne pulse Doppler radar is a key threat to the military helicopter,and assessing the stealth performance of helicopter against airborne early warning radar is helpful to the helicopter’s stealth design and operational planning.In this paper,the Shooting and Bouncing Ray(SBR)and Uniform Theory of Diffraction(UTD)based high-frequency algorithms are used to calculate the Radar Cross Section(RCS)of helicopter,and the radar range equations are used to evaluate the stealth performance.In order to account for the effects of rotor flapping motions during actual flight,the aerodynamics model of whole helicopter is established and the attitudes and controls of helicopter at different flight states are trimmed and input into the RCS calculation module.The effects of helicopter flight speed,flying direction and operational environment on radar stealth performance are studied in focus.It is demonstrated by the results that the trimming control does have a great influence of more than 5 dB on the RCS of helicopter,and the introduction of the trim calculation brings the helicopter’s returns calculation closer to the reality.Variations in flight speed lead to the changes in the stealth performance of helicopter against Early Warning Aircraft(EWA),and the helicopter flight speed can be planned according to the operational requirements to minimize exposure distance or exposure time.Variations in flying direction mainly affect the detection properties of helicopter returns,and flying in the same direction with EWA usually gives the helicopter better low-observability than flying head-on.Variations in operational environment mainly affect the radar detection performance and the sensitivity of the detection performance to external factors;the same amount of change in some external factor causes a different amount of change in the helicopter’s detectability in different environments.