Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-mg02.r1000.mx.aol.com (Internet Inbound) with ESMTP id 4FA3B380000AA; Sun, 9 Oct 2011 08:00:43 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1RCs2l-00068E-Ts for rs_out_1@blacksheep.org; Sun, 09 Oct 2011 12:59:47 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1RCs2l-000685-4n for rsgb_lf_group@blacksheep.org; Sun, 09 Oct 2011 12:59:47 +0100 Received: from mout6.freenet.de ([195.4.92.96]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1RCs2j-0006mr-Ry for rsgb_lf_group@blacksheep.org; Sun, 09 Oct 2011 12:59:47 +0100 Received: from [195.4.92.141] (helo=mjail1.freenet.de) by mout6.freenet.de with esmtpa (ID dl4yhf@freenet.de) (port 25) (Exim 4.76 #5) id 1RCs2i-00029o-Fb for rsgb_lf_group@blacksheep.org; Sun, 09 Oct 2011 13:59:44 +0200 Received: from localhost ([::1]:49833 helo=mjail1.freenet.de) by mjail1.freenet.de with esmtpa (ID dl4yhf@freenet.de) (Exim 4.76 #1) id 1RCs2i-0004ZZ-9f for rsgb_lf_group@blacksheep.org; Sun, 09 Oct 2011 13:59:44 +0200 Received: from [195.4.92.22] (port=49926 helo=12.mx.freenet.de) by mjail1.freenet.de with esmtpa (ID dl4yhf@freenet.de) (Exim 4.76 #1) id 1RCs08-0003Oy-2V for rsgb_lf_group@blacksheep.org; Sun, 09 Oct 2011 13:57:04 +0200 Received: from blfd-5d8213c6.pool.mediaways.net ([93.130.19.198]:2468 helo=[192.168.178.21]) by 12.mx.freenet.de with esmtpsa (ID dl4yhf@freenet.de) (TLSv1:CAMELLIA256-SHA:256) (port 465) (Exim 4.76 #1) id 1RCs07-0003xn-NY for rsgb_lf_group@blacksheep.org; Sun, 09 Oct 2011 13:57:04 +0200 Message-ID: <4E918C0E.30401@freenet.de> Date: Sun, 09 Oct 2011 13:57:02 +0200 From: wolf_dl4yhf User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:7.0.1) Gecko/20110929 Thunderbird/7.0.1 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <4E91694C.8060900@orange.fr> <4E9169AD.8090609@wanadoo.fr> In-Reply-To: <4E9169AD.8090609@wanadoo.fr> X-Spam-Score: 1.6 (+) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001,HTML_TAG_EXIST_TBODY=0.126,RATWARE_GECKO_BUILD=1.426 Subject: Re: Fwd: Re: LF: Laser link... Content-Type: multipart/alternative; boundary="------------060503060806050703040706" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.6 required=5.0 tests=HTML_20_30,HTML_MESSAGE, HTML_TAG_EXISTS_TBODY autolearn=no version=2.63 X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false x-aol-global-disposition: G X-AOL-SCOLL-SCORE: 0:2:447812544:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d60ca4e918ceb2419 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none This is a multi-part message in MIME format. --------------060503060806050703040706 Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 8bit Hi all, just my few cents.. if you frequency-modulate the LF (or VLF) signal with a reasonable square-wave carrier, there are no problems with linearity. Any reasonable CMOS VCO will suffice. Similar for the receiver. Absolutely no need to 'go digital', when the supplied power is limited. Cheers, Wolf . (who tried something similar with a red 'Luxeon' LED some time ago, but the system wasn't reliable lacking affordable narrow-band optical filters for the receiver) Am 09.10.2011 11:30, schrieb Jean-L. RAULT: > > > > > > > > > > > > > > I wonder if an analog laser link has enough linearity to carry your LF > signals (bad lienarity ==> noise and intermod effects) > A digital laser link would be better, but would increase the complexity > of the project :o) > > Jean-Louis F6AGR > > > > > > Le 08/10/2011 19:26, Stefan Schäfer a écrit : > > Thanks Dex and Scott, > > > > Enough stuff to study now. The seconds page seems more useful for me. > > Ok about that OT. > > > > 73, Stefan > > > > Am 08.10.2011 21:09, schrieb Scott Tilley: > >> Hi Stefan > >> > >> http://www.k3pgp.org/laser.htm > >> > >> I use his detector and modulator circuits for my system. > >> > >> 73 Scott > >> > >> > >> > >> > >> On 10/8/2011 10:09 AM, Stefan Schäfer wrote: > >>> LF, > >>> > >>> Just thought about trying a LF RX in the forest and feed the signal > >>> via a laser link to the building here. There is a good direct view > >>> to several suitable places, a good 1000m distant from the city. A > >>> simple laser diode, driven at 15 to 20 mA should work fine for some > >>> hours when having a solar panel that charges during the day. You > >>> know these small lamps for the garden with a solar panel, switching > >>> on automatically when it gets dark... > >>> Just seen HA6PC at OE3GHB-grabber but nothing here or at DF6NM (yes > >>> Mal, i know, you've all worked them in the past...). > >>> Pure AM is probably not the best choice, rather FM. > >>> Does someone of you has useful experiance of such a laser system or > >>> even a ready to use circuit or some hints about a compact IC that > >>> does the job? > >>> > >>> No warnings about the danger of laser light please. > >>> > >>> 73, Stefan/DK7FC > >>> > >>> PS: Sri for beeing a bit OT > >>> > >>> > >> > > > > > --------------060503060806050703040706 Content-Type: text/html; charset=ISO-8859-15 Content-Transfer-Encoding: 8bit Hi all,

just my few cents..

if you frequency-modulate the LF (or VLF) signal with a reasonable square-wave carrier, there are no problems with linearity. Any reasonable CMOS VCO will suffice. Similar for the receiver. Absolutely no need to 'go digital', when the supplied power is limited.

Cheers,
    Wolf .

(who tried something similar with a red 'Luxeon' LED some time ago, but the system wasn't reliable lacking affordable narrow-band optical filters for the receiver)

Am 09.10.2011 11:30, schrieb Jean-L. RAULT: 












I wonder if an analog laser link has enough linearity to carry your LF 
signals (bad lienarity ==> noise and intermod effects)
A digital laser link would be better, but would increase the complexity 
of the project :o)

Jean-Louis F6AGR





Le 08/10/2011 19:26, Stefan Schäfer a écrit :
> Thanks Dex and Scott,
>
> Enough stuff to study now. The seconds page seems more useful for me.
> Ok about that OT.
>
> 73, Stefan
>
> Am 08.10.2011 21:09, schrieb Scott Tilley:
>> Hi Stefan
>>
>> http://www.k3pgp.org/laser.htm
>>
>> I use his detector and modulator circuits for my system.
>>
>> 73 Scott
>>
>>
>>
>>
>> On 10/8/2011 10:09 AM, Stefan Schäfer wrote:
>>> LF,
>>>
>>> Just thought about trying a LF RX in the forest and feed the signal 
>>> via a laser link to the building here. There is a good direct view 
>>> to several suitable places, a good 1000m distant from the city. A 
>>> simple laser diode, driven at 15 to 20 mA should work fine for some 
>>> hours when having a solar panel that charges during the day. You 
>>> know these small lamps for the garden with a solar panel, switching 
>>> on automatically when it gets dark...
>>> Just seen HA6PC at OE3GHB-grabber but nothing here or at DF6NM (yes 
>>> Mal, i know, you've all worked them in the past...).
>>> Pure AM is probably not the best choice, rather FM.
>>> Does someone of you has useful experiance of such a laser system or 
>>> even a ready to use circuit or some hints about a compact IC that 
>>> does the job?
>>>
>>> No warnings about the danger of laser light please.
>>>
>>> 73, Stefan/DK7FC
>>>
>>> PS: Sri for beeing a bit OT
>>>
>>>
>>
>
>

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