[Laser] New San Diego optical beacon

[M0EME Paul Tomlinson]

I'm interested reading this... a while ago I made a pcb with 230 very!!! 
bright white leds, I used white because I got them cheap from ebay! I 
planned to use it as a beacon from my house and shine it straight up sending 
slow Morse modulated at about 400Hz, then drive away to some high spots 
around and see if I could pick it up....
I also made a 4" receiver and preamp using the K3PGP design and a TBA820 op 
amp into the phones and laptop.
Up till now I never did get round to doing this, but if anyone else has 
tried this i would love to hear and spur me on to get it done for myself.
Thanks Paul Tomlinson M0EME


----- Original Message ----- 
From: "Kerry Banke" <kbanke at qualcomm.com>
To: "Free Space LASER Communications" <laser at mailman.qth.net>
Sent: Monday, January 22, 2007 4:29 PM
Subject: [Laser] New San Diego optical beacon


>
> Art - Thanks for asking as your timing was perfect:)    Over the  weekend 
> we installed a new 180 degree optical beacon which is a surplus  red FAA 
> radio tower beacon we happened to obtain and made functional.  The 
> original unit was a 360 degree beacon with about 300 LEDs but we have 
> split it in two as the location only needs to service 180 deg.  Right now 
> the beacon draws 17 Volts at 4 amps and is producing a 450 Hz crystal 
> controlled tone (50% duty cycle square wave). We made a screen capture and 
> .wave file recording at 8 miles  using my 4" optical receiver and Spectrum 
> Lab. Spectrum lab shows the signal as about 50 dB above the noise in a 1 
> Hz BW.    I'll be happy to send it to anyone interested.  The 
> scintillation was about 50% which is not bad compared to some previous 
> attempts with a single high output LED beacon. Some of it I'm sure is the 
> time of year but also probably the fact that the beacon now is not quite 
> such a point source. The LEDs are spread over a 12" high area which should 
> help scintillation.  We're working on the next step which will probably 
> include adding MP3 player capability for a beacon message ( maybe PSK31, 
> Jason,  other?) and also a linear optical repeater.  Stay tuned.
>  - Kerry N6IZW  with the Sand Diego Microwave Group -
>
> At 02:46 PM 1/19/2007, you wrote:
>>Hey Kerry, how 'bout an update on your LED dx activity there? I know you 
>>did some 20 mile qso's with LED's.
>>
>>Any more new adventures?
>>
>>Art
>
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