Research On Transmission Performance With Light Propagating Through Atmosphere And Sea

Spaceborne Laser Submarine Communication, has being an interestedcommunication technology, due to its data transfer rate higher than current communicationmethod, and be helpful for hiding submarine trace during communicating. The research ofSLSC is the important for military application. It includes, the research of atmosphere andseawater, spaceborne lidar manufacture, receiving antenna manufacture, and signalprocessing technology, etc.This dissertation analyses the laser pulse transmission through atmosphere andseawater, and gives some advice for designing spaceborne laser, such as the output power,the beam divergence angle, orbit altitude, pulse repeat rate, the configuration of PPM. Itsmain contributions are as follows.The optical scatterance and attenuation properties of physical constituents inatmosphere/sea optical channel are studied and summarized in the paper.The application of Monte Carlo method in simulating the transport of photons inatmosphere/sea optical channel, and its presumptions, are discussed in detail. Thesediscussed contents involve photon's position after collision happened, moving direction,free distance for photon traveling through scatter medium, stopping judgment, comparisonand choice of scattering phase function.The calculations of spatial spreading effects when light traveling in atmosphere andsea scattering channel, are finished in the paper. The power distributions of laser signal onconditions of different orbit altitude, vary divergence angle of transmitter, sea areachanged, and different under-water target depths are studied in detail. The powerdistributions can be reference for confirming some working parameters of space laser.With the laser communication energy fuction, the propagation attenuation of the lasersunmarine communication is estimated in theory. At the same time, the Monte Carlomethod is introduced for calculating the propagation attenuation following with the lightpulse traveling in atmosphere and seawater channel. These calculation are finished withsome different conditions, including of different orbit altitude, vary divergence angle oftransmitter, sea area changed, and different under-water target depths. The both estimationresults are contrasted.The paper finishes the calculations of multipath temporal spreading effects followingwith photons traveling in the atmosphere and the seawater. The multipath temporal spreading distributions of laser signal on conditions of different orbit altitude, varydivergence angle of transmitter, sea area changed, and different under-water target depthsare discussed. These calculations can give some advices for obtaining the pulse repeat rateof laser and the PPM frame format.Based on these above-mentioned results about temporal spreading and spatialspreading, the limit of current national laser, abroad laser communication satellite whichsucceeded in satellite- satellite communication or satellite - earth platform communication,the dissertation proposes some laser transmitter parameters about output energy, pulserepeat rate, the beam divergence angle, orbit altitude, laser wavelength, and theconfiguration of PPM. At the same time, the data transmitting rate is calculated withcorresponding parameters of laser transmitter and PPM frame.In the end, the paper gives some assumptions about researching the transmitionperformance with the light traveling through atmosphere and seawater channel.