[tiagod]

Please correct me if I'm wrong, but I guess if you aim well enough, there could be a very long, narrow, non-reflective cylinder in front of the receiver that would block all light that is not coming exactly from the direction of the target satellite.

[scottLobster]

"If you aim well enough" is doing a ton of work there. Precise real-time optical tracking of a satellite from a moving platform is an extremely difficult problem. Even if the satellite itself is geostationary, it would also have to rotate to keep the "cylinder" pointed in the right direction to maintain signal.

I suppose you could make a "cylinder" or "cone" broad enough that, if the threat was static, could blot-out attempted jamming from only certain regions while staying open facing toward friendly zones.

[cyberax]

It's a geostationary sat. It doesn't move.

[scottLobster]

No, but the airplane it would be talking to does. Hard enough when your transceiver is wide open, if you narrow your FOV to a thin cone in order to block jamming signals, the GEO now has to physically track the airplane somehow.

Either the whole satellite rotates or the transciever is on a mount that can rotate

[vlovich123]

Unless you plan on having 1 satellite per airplane, something tells me it's harder to constrain the FOV than you might suggest. There's also the small problem of the energy, complexity, & weight of having motorized parts on the satellite (or fine-grained attitude control for the satellite itself to track the craft).

[scottLobster]

Agreed, my point is it's a lot harder than tiagod made it sound.

It also doesn't account for some kind of mobile jammer making it inside the cone, particularly if it's staring at an adversarial nation where secure comms would be needed the most, but the adversary would have freedom of movement.

[Onavo]

You will probably need to increase the gain (better lens, photomultipliers) on the receiver photodiode too.

[trashb]

your assuming the target satellite doesn't reflect?