[Laser] RTTY over light, anyone tried it?

[Garnier Yves]

Paolo,
The simplest is to use PC to PC optical links with sound cards and squared output signals to drive your LED.
You can use many TX RX protocols.
With rather strong signals you can use all the PSK31 programs.
With NLOS and very weak signals use JT65A from K1JT or the I2PHD JASON programs.
73 Yves F1AVY  

Paolo Cravero <pcravero at as2594.net> a écrit : Hi.
I'm slowly coming up with an optical transceiver, with the help of an 
astronomer for the mechanical part.

So far I have built an MCW transmitter and an OPT202 receiver. The TX is a 
10mm red LED, and soon the RX will have a nice telescope mount so that first 
"beaconed" outdoor tests can take place. No-lens tests took part indoor on 12m 
paths, both LOS and NLOS.

But since the astronomer doesn't know Morse code, and is not a licensed HAM, I 
am looking for a simpler way to establish two-way communications. A keyboard 
to keyboard mode would keep the system simple and let non-HAMs enjoy that part 
of the spectrum.

The old fashioned RTTY came to my mind (two tones, FSK), so before I start 
building stuff, here I ask: are there any records of optical RTTY 
communication attempts?

There was a PSK31 discussion few months ago, but in the archives Google didn't 
find any mention to RTTY/FSK.

I am thinking of the usual XTAL > divider chain with a MUX to generate the 
(A)FSK from a serial/parallel port binary output. Or should I better take the 
soundcard output, square it (op-amp in comparator mode) and drive the light 
source?

Thank in advance for any input/pointer.
Paolo IK1ZYW

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Yves F1AVY
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