[Laser] led txr

[John Randall]

Hi Mike , thanks for the tip. Will be playing around a bit and see whats what. 
Just added a 555 ic tone gen to the setup. My setup is very basic and can be 
seen on my website under /misc/lasers.

http://m0els.5gigs.net/index.html

I was thinking of using bicycle white reflectors glued together. Would they work 
?

73
John





________________________________
From: Mike <mikecouture at bellsouth.net>
To: Free Space LASER Communications <laser at mailman.qth.net>
Sent: Fri, 5 November, 2010 5:11:50
Subject: Re: [Laser] led txr

John,



Good luck aligning the mirror. You might try a 'retro' reflector. You can be
off quite a bit and still receive a return. Basically it's 3 mirrors at 90
deg angles, think of the corner of a room, i.e. 3 sides.



Mike C.

(FL w. sandbar)



  _____  

From: laser-bounces at mailman.qth.net [mailto:laser-bounces at mailman.qth.net]
On Behalf Of John Randall
Sent: Thursday, November 04, 2010 3:04 PM
To: Free Space LASER Communications
Subject: Re: [Laser] led txr



Hi Stuart, Still feeling my way around laser comms and baseband usuage. I
have
yet to try it over any considerable distance, other than across the front
room....hi. There is a field nearby which has a bit of space, so might go an
play there one evening. I would have to use a mirror on the opposite end to
get
the beam back to the detector. Should be fun trying to set it up.
Nice one on the distance you achieved. I also found the aussie laser
reflector,
so that will make more interesting reading.hi

73
John



________________________________
From: I <stuart.wisher at talktalk.net>
To: laser at mailman.qth.net
Sent: Thu, 4 November, 2010 15:17:14
Subject: [Laser] led txr


John,



we use lenses (100mm glass, or A4 size fresnel) to focus the beam here, so
the
lensed products may be more intense, but not effectively brighter when
focussed.
Our signals, FM or SSB go out on a 25kHz or so sub-carrier, so we need a
high
speed detector. I am still amazed an ldr works at all. A laser might be fine
at
short range, but you try aiming it at distance, I have done it at 15km,
nearly,
but not quite impossible. Even aiming the led is difficult with its
effective
one tenth of a degree beamwidth (calculated and confirmed by measurement).


By the way, we were out again last night and successfully completed a 65km
contact between me, G8CYW and G8KPD/G8PNN. Signals were still end-stopping
on FM
and SSB. We could even continue when the signal disappeared to the naked eye
when mist formed, we held the link for about an hour.


Stuart, G8CYW
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