[Laser] daytime optical contacts

[Stuart]

Tim,
Some interesting ideas in your post.


Taking them from the top, I think the thing to do with a laser would be to use a beam expander out to 
at least 100mm diameter, then it would simply work in reverse on receive. I have been


 told by someone over here that laser diodes will work on receive. I have a 200mW laser with a variable


 focus lens which I can open out to fully illuminate my 150mm telescope primary mirror, making it 


effectively a 150mm beam expander. I simply remove the eyepiece and replace it with the laser suitably


 adjusted. With this I can project a tight beam with very little diffraction over miles of countryside here.


 If the laser can be made to work on receive it would make a good receiver also.



To use a single optic with separate devices would entail a beam splitter, which is getting complicated and places 
limitations on the efficiency of the set-up.



We do have a concentration of operators and stations here in the north of England, Eight active separate stations 
within 100 miles or so of my station. I have worked six different stations in the past months over various paths, some of them 
on two or three different wavebands, 630nm, 850nm and 940nm.



Currently, further south, there is a lot of interest in NLOS working, moves are being made to set up beacons
using weak signal modes to help with development, so your dream of a NLOS net may come true at some 
point here. One station has shown me a 50W  panel of blue LEDs intended for scatter work.



I am glad you got the point regarding the simplex made rather than multiplex. It is much less complex
and gives the receiver the chance to optimise reception and hence transmission.



At this stage tonight it looks as if the 46km 850nm NIR attempt is on for tomorrow, we aim to start right on local 
noon, and not use visual aids if possible.

Stuart