2013/9/26 Eugen Leitl

It's really hard to jam the sky, especially in VIS range.

"Huh. Guys, what's that on our radio scanner? Someone calls us?" Hard to jam, easy to trace. Even regular Dutch police forces have triangulation tactics to find pirate radio stations. This is where I'm more enthusiastic about near-optical connections. A laser, invisible spectrum ofc, and a small black surface (iow:detector) are all it takes. It will still be visible (at night) with special hardware. Street lanterns (depending on the type) might make them invisible at night too. Bandwidth is wonderful, and there's plenty of spectrum to duplicate bandwidth too. Quite like fiber, except for the ideal transmission. And that highlights the problems. You have to keep the laser pointed, that means not diffracted by thermic differences or blocked by dust and other particles (like, you know, leaves). This might be less trouble than it'd seem at first, and even better it can be automated by a lens system. A just graduated ship's lieutenant laughed at me for suggesting laser communication as the future. "No spying, very high speed, very wide bandwidth!" and he effectively answered "Line of sight, irreliable, no need for speed and just use satellite". A yagi pointed skywards should be hidable inside the house, so I guess he's somewhat right.

On Thu, Sep 26, 2013 at 09:20:43AM +0200, Lodewijk andré de la porte wrote:

2013/9/26 Eugen Leitl

...

It's really hard to jam the sky, especially in VIS range.

"Huh. Guys, what's that on our radio scanner? Someone calls us?"

They want to pick up a parabolic dish, a LoS laser or a phased array tracking a point source overhead, all sending at maybe 5-10 W power? Sure, if your sky is thick with mapping drones. Sounds like a fifth world problem.

Hard to jam, easy to trace. Even regular Dutch police forces have triangulation tactics to find pirate radio stations.

Isotropic radiators with high power are easy to spot. Dynamic tight beams need at least a passing point of alignment to get a position fix on the ground station. NSA sigint used that microwave LoS interception, but this wouldn't scale for millions of users and very brief low-power bursts during random alignment events.

This is where I'm more enthusiastic about near-optical connections. A laser, invisible spectrum ofc, and a small black surface (iow:detector) are all it takes. It will still be visible (at night) with special hardware. Street lanterns (depending on the type) might make them invisible at night too. Bandwidth is wonderful, and there's plenty of spectrum to duplicate bandwidth too. Quite like fiber, except for the ideal transmission.

Or maybe you just buy http://www.ubnt.com/airfiber or the lower-grade gear for LoS.

And that highlights the problems. You have to keep the laser pointed, that means not diffracted by thermic differences or blocked by dust and other particles (like, you know, leaves). This might be less trouble than it'd seem at first, and even better it can be automated by a lens system.

A just graduated ship's lieutenant laughed at me for suggesting laser communication as the future. "No spying, very high speed, very wide bandwidth!" and he effectively answered "Line of sight, irreliable, no need for speed and just use satellite".

A yagi pointed skywards should be hidable inside the house, so I guess he's somewhat right.

Phased arrays which are flat or half domes are compact and don't look like anything from air. If you're clever, you can integrate these into a PV panel.

On Wed, Sep 25, 2013 at 11:51 PM, Eugen Leitl wrote:

... I'm optimizing against people who walk up, and dismantle your wireless mesh, or down the Internet in your country.

down the Internet; the mesh lives on. down the mesh? hope you've got capacity for a truck roll to tens of millions!

... It's really hard to jam the sky, especially in VIS range.

not true. :/

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 09/26/2013 04:15 AM, coderman wrote:

mesh is much more robust in every aspect... presuming you can scale (there's always a catch...)

There are ways to make it more scalable but I don't think perfectly so. The question is, are 21st century people more willing to use a "send it and it'll get there" method ala the Net as it is now, or a "post it and we'll get it there if we have to teach carrier pigeons to use a tarot deck and a vuvuzula, though it might take a while" method (in other words, FidoNET-like). The latter gets the job done but whether or not people are willing to be patient in light of that kind of latency is a different question entirely. For what it's worth, Byzantium's working on a store-and-forward-like architecture (mobile clients to sort-of stationary mesh nodes with semi-persistent storage) for all of its apps (not just the microblog - thanks again, Richo!). As for the forward bit, we're working on a sufficiently generic implementation of the latter technique (which could use everything from amateur radio (as problematic as that might be) to sneakernet) to eventually synchronize all reachable nodes' content. Ways and means. - -- The Doctor [412/724/301/703] [ZS] Developer, Project Byzantium: http://project-byzantium.org/ PGP: 0x807B17C1 / 7960 1CDC 85C9 0B63 8D9F DD89 3BD8 FF2B 807B 17C1 WWW: https://drwho.virtadpt.net/ "The building was on fire, and it wasn't my fault." --Harry Dresden -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.20 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iEYEARECAAYFAlJJ2L8ACgkQO9j/K4B7F8HI4ACfSi+c4DIz8EvLGchfHSd9oBky KUUAnioGhI7zy9ZTobLnS4WOCxTl/4i9 =r2M9 -----END PGP SIGNATURE-----