[Laser] Fresnel LED TX - test over 94km

[Jim Moss]

Robo & Rado,
Very interesting!
What method did you you use for alignment?
Visual or signal?
How wide was your measured beam width?

Jim
N9JIM





----- Original Message ----
From: "Vlacilik, Radovan" <Radovan.Vlacilik at siemens.com>
To: Free Space LASER Communications <laser at mailman.qth.net>
Sent: Fri, September 10, 2010 6:37:43 AM
Subject: [Laser] Fresnel LED TX - test over 94km


Hi all,

We (Robo OM1LD and I) tested the prototype of the Optical transmitter
with LED. The test was only one way TX on the hill and RX 94km far
apart. The path was similar with our last one.


TX - Velka Javorina, 965m ASL, Loc JN88UU
- LED Luminus SST90 drived at 5 Amps DC
- 50% Duty cycle from NE555 (near one that I have in Test LED TX
- optical arrangement was LED - Shallow mirror, Condenser Lens (short
FL), Cheap fresnel lens
- divergence about 100mRad (2m spot diameter in 20m)
- it is only prototype, so there fore it has open design, and it is
quality wood concept ;-)


RX - Near Samorin, Loc JN88QA
- oboR RX design with 72mm lens


We tried to compare the prototype Fresnel LED TX with Test Led TX and
Halogen beacon. The visibility was only 50km. Therefore the Test LED TX
was not seen in Samorin. Fresnel LED TX was seen weakly, but without
problems. The halogen beacon was weaker than Fresnel LED TX.
Unfortunately, Mr. Murphy was with us again - we do not have any audio
recorded because the MP3 recorder did not work.

The prototype confirmed that this is the way. So we ordered the better
fresnels from Anchor Optics ;-)

Some photoes you can find here:
http://om2zz.blogspot.com/



We have to do more developing and more tests.


Robo OM1LD and Rado OM2ZZ
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