[Laser] RE:Glenn Thomas

Mon Aug 21 19:49:05 EDT 2006

The only requirements is that it can operate at a bit rate of 10Gbits/sec 
and is available 24/7. No constraints on cost or location. It is to 
communicate from the earth to the moon. Safety isn't really any issue either 
because i can always account for it in my feasibility study e.g it is not a 
good idea because this design is unsafe.

>From: laser-request at mailman.qth.net
>Reply-To: laser at mailman.qth.net
>To: laser at mailman.qth.net
>Subject: Laser Digest, Vol 26, Issue 9
>Date: Sun, 20 Aug 2006 04:01:15 -0400 (EDT)
>
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>Today's Topics:
>
>    1. Re: Earth moon communications (Glenn Thomas)
>    2. Re: Earth moon communications (John Weaver)
>    3. Re: MFSK for Light? (F1AVYopto at aol.com)
>
>
>----------------------------------------------------------------------
>
>Message: 1
>Date: Sat, 19 Aug 2006 07:18:10 -0700
>From: Glenn Thomas <glennt at charter.net>
>Subject: Re: [Laser] Earth moon communications
>To: Free Space LASER Communications <laser at mailman.qth.net>
>Message-ID: <7.0.1.0.2.20060819070430.033d4e88 at charter.net>
>Content-Type: text/plain; charset="us-ascii"; format=flowed
>
>Iona -
>
>Can you tell us a bit more about your system requirements? For
>example, how much bandwidth is it supposed to provide? How reliable
>is it supposed to be? Is it supposed to communicate between earth and
>moon or communicate between two places on earth by bouncing a laser
>off the moon? Any cost constraints? Any constraints on where the
>communications stations can be located? Safety constraints on the laser 
>itself?
>
>A few months (February/March) ago here was a fairly extensive thread
>on here about bouncing lasers off the moon or possibly off the Apollo
>laser reflectors. You might take a look at it.
>
>Good luck.
>
>73 de Glenn Thomas
>
>At 11:51 PM 8/18/2006, you wrote:
> >Hello,
> >I was wondering if anyone would be able to give me some advice on
> >long distance laser communications. I have an assignment to design a
> >earth moon laser communications system and only really know a tiny
> >bit about lasers. any information would be much appreciated.
> >
> >Thank you!
> >
> >_________________________________________________________________
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>------------------------------
>
>Message: 2
>Date: Sat, 19 Aug 2006 07:52:35 -0700 (PDT)
>From: John Weaver <kg6one at kg6one.org>
>Subject: Re: [Laser] Earth moon communications
>To: Free Space LASER Communications <laser at mailman.qth.net>
>Message-ID: <20060819073346.V92807 at carbon.ehzed.com>
>Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed
>
>I am not an expert. I don't even play one on the internet. This is based
>on things I've seen others write in response to this question.
>
>Laser EME requires *alot* of power, good recievers and good software.
>For most people this is a "give up" condition, but there are dedicated
>Hams and high power laser enthusiasts who are making it work.
>
>http://www.k3pgp.org/laser.htm
>http://members.misty.com/don/laserfaq.htm
>
>Ack! You are asking about EM communications. The info in those links
>should get you started.
>
>On Sat, 19 Aug 2006, Iona Stenhouse wrote:
>
> > Hello,
> > I was wondering if anyone would be able to give me some advice on long
> > distance laser communications. I have an assignment to design a earth 
>moon
> > laser communications system and only really know a tiny bit about 
>lasers. any
> > information would be much appreciated.
> >
> > Thank you!
> >
> > _________________________________________________________________
> > realestate.com.au: the biggest address in property
> > http://ninemsn.realestate.com.au
> >
> > _______________________________________________
> > Laser mailing list
> > Laser at mailman.qth.net
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>
>
>------------------------------
>
>Message: 3
>Date: Sat, 19 Aug 2006 15:42:12 EDT
>From: F1AVYopto at aol.com
>Subject: Re: [Laser] MFSK for Light?
>To: laser at mailman.qth.net
>Message-ID: <556.5840ff5.3218c394 at aol.com>
>Content-Type: text/plain; charset="UTF-8"
>
>Dans un e-mail datÃ© du 19/08/2006 05:58:01 Paris, Madrid (heure d'Ã©tÃ©),
>TWOSIG at aol.com a Ã©crit :
>
>"I am wondering about your experience with laser  comm and JASON.  Was  the
>light modulated with sine waves, that  is, linearly?  Or were the  
>frequency
>tones
>square waves, that is,  turning the laser fully on or off?"
>
>James
>JASON from I2PHD works with  IFK. (Incremental frequency keying)
>Three consecutive audio tones give two  frequency offsets that code one
>character.
>It is a very powerful program able  to extract a -40 dB under noise signal 
>in
>a 2500 Hz global audio bandwidth.  (slow mode).
>We used the JASON V099 program to communicate by night over 40  km by
>bouncing light off a hillside near Lyon in  France.
>(http://us.share.geocities.com/f1avy/NLOS_LASER_EXPERIMENTS2.pdf)
>At  normal speed only 2 to 3 characters are sent each minuteâ€¦
>This program is  well adapted for very low level laser echoes on a fix 
>target
>or for a very far  large area beacon (ex. columns of LEDs).
>We use a 75 Hz central frequencies  to escape the strong spurious from 
>public
>lights (in Europe 50 Hz 100Hz 300 Hz  are the strongest lines) and to keep
>the best sensitivity point on the slow PGP  RXs.
>Our lasers are basically powered by constant current generators near  their
>maximum output optical power.
>The constant current generator supply is  modulated by a chopper.
>This chopper is driven by the PC sound card output  (sin wave).
>With a 500 mV peak to peak PC output, the current generators give  perfect
>square waves on the laser diode.
>With a lower audio level and a  reduced current, our chopper becomes a 
>linear
>modulator that can pass audio  voice or multi-tunes modulations.
>In this last case the current generator works as safety current  limitor.
>For a square wave, the fundamental term is amplitude equivalent to  the one
>gives by a linear driver in sine wave so JASON works perfectly  well.
>For a powerful laser the driver and the chopper schematic can be found  in 
>:
>http://pageperso.aol.fr/F1AVYopto/CLOUDBOUNCEUK2.pdf
>Yves
>F1AVY
>
>
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>End of Laser Digest, Vol 26, Issue 9
>************************************

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