CENTROID ANGLE OF ARRIVAL TEMPORAL POWER SPECTRUM FOR SPHERICAL WAVE PROGATION THROUGH THE TURBULENT ATMOSPHERE BETWEEN TWO MOVING VEHICLES

The centroid angle of arrival temporal power spectrum for spherical wave propagation through the turbulent atmosphere with both source and receiver moving and wind blowing across the propagation path is derived. Two optical systems are considered. In the first system, the receiver does not have to track the source, and the received beam spot may fall off the optical axis. The time dependent wave equation is solved using the fixed coordinate system. In the second system, the receiver has to track the source, and the received beam spot always falls on the optical axis. The time dependent wave equation is solved using the rotating coordinate system. The Taylor hypothesis which is valid in this rotating coordinate system is also derived. Also, the source and receiver are allowed to move in the arbitrary direction with constant velocity. In both systems the phase is found to consist of a deterministic component due to Doppler shift and a random component due to refractive index fluctuation. The low frequency part of the power spectrum increases with frequency following a power law and is dominated by aperture diffraction. The high frequency part of the power spectrum decreases with frequency with no fixed slope and is dominated by refractive index fluctuation. The peak of the power spectrum is determined by the outer scale value.