Calculating Power Loss in FSO: A Study of Free Space Optics

[juan1]

Homework Statement

Well, I´m doing a project about FSO (Free Space Optics), it deal with optical communication but without fiber, only by air. Then, I have already studied the transmitter (gaussian source), the channel and I know I need a photodetector APD for the receiver but my questions is: how can I study how much power there is on the receiver?
I also know power on the receiver is the difference between power on the transmitter and loss on the way. Nevertheless in the receiver a bit of power is lost because of the aceptation cone.
So how can I calculate this energy loss??

Thank you for help me.

Homework Equations

The Attempt at a Solution

 

[NateD]

The power at the receiver can be calculated using the following equation: P_rec = P_tx - L_tx + L_rx - L_cone where P_rec is the power at the receiver, P_tx is the power at the transmitter, L_tx is the transmission loss, L_rx is the reception loss and L_cone is the loss due to the acceptance cone. You can calculate the transmission loss using the Friis Transmission Equation: L_tx = (4πd)^2G_txG_rx/λ^2 where d is the distance between the transmitter and receiver, G_tx is the antenna gain of the transmitter, G_rx is the antenna gain of the receiver and λ is the wavelength of the signal. You can calculate the reception loss using the Friis Reception Equation: L_rx = (4πd)^2G_txG_rx/λ^2 where d is the distance between the transmitter and receiver, G_tx is the antenna gain of the transmitter, G_rx is the antenna gain of the receiver and λ is the wavelength of the signal. Finally, you can calculate the loss due to the acceptance cone by calculating the power in the cone and then subtracting it from the total power: L_cone = P_total - P_cone where P_total is the power outside the cone and P_cone is the power inside the cone.