Analysis of level crossing scintillation statistics for 0.83 μm propagation on 4.1 km path across central London

The level crossing statistics for the measured amplitude scintillations of a 0.83 μm laser beam propagating across a 4.1 km path in central London are analysed in terms of the normalised irradiance of the received signal in dB. The level crossing probability density function, the number of times a level was crossed and the mean time duration of events are calculated for different turbulent conditions. The results are similar to ITU predictions for microwave frequencies. This study can help in the evaluation of the performance of a digital free space optical communication link