Caracterizarea statistica a timpului de intarziere intr-un sistem laser terestru de comunicatii

Autor/autori: Radu DRAGOMIR

Rezumat: Perturbatiile atmosferice produc fluctuatii ale intensitatii fasciculului laser in propagare prin canalul terestru de comunicatii. Caracterizarea statistica a micilor fluctuatii apeleaza aproximarea Rytov si utilizeaza media si covarianta functiei de unda. Fluctuatiile intensitatii sunt modelate printr-o distributie lognormala. Sunt analizate covarianta temporala a fluctuatiilor intensitatii, imprastierea timpului de intarziere, fluctuatiile de polarizare, precum si o arhitectura de receptor. Este analizata rata erorilor de bit (BER) pe o schema de decorelare a fluctuatiilor de intensitate

Cuvinte cheie: fluctuatie, intensitate, laser, comunicatii


Abstract: Atmospheric turbulences make the laser beam intensity fluctuates while travelling through the communications channel. The Rytov approximation, the statistical mean, and the statistical covariance are used to describe the weak intensity fluctuations of the laser beam. A lognormal probability density function produces the intensity fluctuations model. The present paper points out to important time delayed diversity issues, such as time covariance of the intensity fluctuations,laser polarization fluctuations, and diversity receiver architecture. The bit error rate (BER) is analyzed in order to characterize the performance of a delayed diversity receiver.

Keywords: fluctuations, intensity, laser, communications.

 

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