"low-latency links", says the article. I wonder if they consider 500 ms ping to be low, or if they want to replace Geostationary with Low Earth Orbit.
"low-latency links", says the article. I wonder if they consider 500 ms ping to be low, or if they want to replace Geostationary with Low Earth Orbit.
> "low-latency links", says the article. I wonder if they consider 500 ms ping to be low, or if they want to replace Geostationary with Low Earth Orbit.
Directional laser beams are orders of magnitude to jam compared to radio wave. That alone makes it of big interest for military applications, even with 500 ms latency.
There is several known cases where jamming caused the loss of costly military drones.
https://en.wikipedia.org/wiki/Iran%E2%80%93U.S._RQ-170_incid...
Laser comms could prevent that entirely.
> Directional laser beams are orders of magnitude to jam compared to radio wave. That alone makes it of big interest for military applications, even with 500 ms latency.
I am reminded of RFC 1217 - Memo from the Consortium for Slow Commotion Research (CSCR) https://www.rfc-editor.org/rfc/rfc1217
I love that this was ostensibly written by Vint Cerf.
It's listed in his computer science bibliography https://dblp.org/pid/c/VintonGCerf.html and https://en.wikipedia.org/wiki/Vint_Cerf#Author
Though the edit for that authorship to the RFC came much later. https://datatracker.ietf.org/doc/rfc1217/history/
Could these not be jammed by blasting the same wavelength laser at said geostationary satellite?
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.
"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.
It's a geostationary sat. It doesn't move.
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
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).
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.
You will probably need to increase the gain (better lens, photomultipliers) on the receiver photodiode too.
Getting it to work with one end stationary first sounds like a reasonable development plan. LEO adds a lot of complexity, but with huge benefits.
OTOH the number of engineers that focus on throughput over latency is quite staggering.
Leo seems easier to me. Geostationary is really far away. Leo is much, much closer. It's easier to hit a buck thats running right past you than to hit a stationary target across the Atlantic.
Especially if you yourself are on a moving platform
I guess if your goal is just to stream aircraft telemetry and black box like recordings then latency may not be high on the agenda.
Black box data doesn't need that crazy throughput either though. Traditional RF is much easier to get right, and works even when the aircraft starts losing track of where it is and stops being able to track the satellite with its laser
I think it's the opposite? For small telemetry you want it now, but for the big data products there's no hope of "now" and so you settle for soon.
Geostationary is easier to hit than a LEO constellation like Starlink. With an LEO target you need to switch at least every 2-4 minutes, Starlink ground stations can switch multiple times per minute but that's for obstacle avoidance in the air you'd only have to switch when the current target moves out of LOS entirely.
I’ll take 500ms ping for those speeds while temporarily on a plane.
No doubt! I’ve measured literal 5 minute ping times on airplanes. 300,000ms. Where are the buffering the packets!?
My guess is that you're getting retransmissions because of dropped frames, not because there's some huge buffer in the sky.
Indicated airspeed 280kts, ground speed 470kts, FL410, the packets are trying to catch up…
I like "huge buffer in the sky".
That's where I imagine all my deleted data goes.
we're all just riding the ring buffer of samsara, maaan
There’s one huge buffer in the sky!
The huge buffers are at the two endpoints (:->