Henri Derksen  wrote:
> Hello Jan,
>
>>>>> People are working on THz (Tera Hertz) links too these days.
>>>>> There is no escape :-)
>>> Wow. How long until we get up to infrared?  Let's see, about
>>> 1000 nm at 300 MHz/meter... 300 THz?
>>> *ESCAPE*.../ESCAPE/...ESCAPE....Escape...escape..... .
>>> ...0x1B...^[...
>>> Oh, wait...
>>> ^C...
>>> OK, to hell with it...
>>> kill -9...
>>> NO CARRIER
>
>> Try
>> rm -rf /*
>
>> We are alreay in IR:
>> http://panteltje.com/panteltje/pic/ir_pic/
>> use it to control my cable receiver from the PC to record movies on the
>> PC on time.
>
> Have you ever seen this:
> RONJA (=Reasonable Optical Near Joint Access)
> http://ronja.twibright.com/about.php
> Free translation to Dutch:
> ZODAT (=Zinvolle Optische Dichtbij Aansluit Toegang)
>
> It gives you an IR wireless link to another friend nearby at 10 MBit FD
> EtherNet. I love this 100 % selfmade connections.
> There are full descriptions of how to build and test this.
> Especially the option to keep de glasses free of condensation for instance.
> For resistors in a rectangle setting for heating the glasses from inside.
> But this RONJA is not suitable on inland ships (my other hobby),
> because of all the movements ships always have ;-(.
> Think about up/down, turn left/right, rolling, stamping, gearing etc.
>
> I also have seen discs in a dome that move in the oposit direction the ship
> moves, to get a constant good link to the satelite they follow.
> That is possible both for tv wathing as an internet link via satelites.
> But they ask such high prices for such equipment and contributions ;-(.
> I think the new DigiTenne DVB-T2 is a more cheaper solution.
> In Germany there is already DVB-T2 for television,
> but in the Netherlands they still only use DVB-T1.
> And only NPO1, NPO2, NPO3 and one local tv-transmission are Free to Air.
>
> I have two information packets avaialble for hobbyists in Dutch.
> One is a selfbuild AIS+ECDIS for inland ships with a Raspberry Pi 2B/3B+.
> And the other are 123 schematics for on board ships electricity.
> Here are the links:
> 
> 
> Good luck with it.
> You know, a Raspberry Pi fits on almost every boat ;-).
>
> Nautical Greetings from Henri at the river Rhine in Arnhem.
>
>

I don’t know what aperture the IR link requires, but I’d look at a
voicecoil-actuated mirror for beam stabilization. These are widely used in
drone camera mounts, for example.

And the use of IR-based “Ethernet” is actually not new. Hewlett-Packard
Laboratory had such a system running in a large building in 1982. It was
considered for a product, but never made it out of the lab (there were some
“gotchas”, like security).

--
-michael - NadaNet 3.1 and AppleCrate II:  http://michaeljmahon.com

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