[NLRS] FYI: Optical QSO

Tue Apr 15 12:20:33 EDT 2025

 Regarding finding longer line-of-sight paths here in the plains of Minnesota, a few ideas.

   - Kiester, EN33EN03.  Southwest of Albert Lea, so not too far away.  Being in southern MN trees are less of a problem then corn.  The Kiester location is essentially tree free in almost all directions and has 12 to 20+ mile horizons.
   - Monticello EN35CG, the Montiview Mountain Bike Course.  Not to far away from Mpls.  Views from west through north thru northeast in the 12 to 15 miles range.  More trees up this way may make finding the other end more difficult.
   - Darwin, EN25tc.  Darwin Winter Park Area.  Bad news is that its about a 1/4 mile hike from the parking lot, but nice views in most directions.  Would need to lug all your stuff up the hill, but not bad.   There are some 18 mile LOS.  Trees are fewer.  Be a fun spot to do a QRP Hilltop operation from.
   - EN25VJ72IG south of St. Augusta.  Some views to the east around 16 miles
   - Summit, SD.  EN15lj.  Wilmont Welcome Center.  Some 25 to maybe 30+ LOS paths.  Trees are less of a problem unless there a farmstead wind break.

73, JonW0ZQ

    On Tuesday, April 15, 2025 at 10:10:11 AM CDT, Rob Jahnke <rcjahnke at gmail.com> wrote:   

 It's great to see some interest in optical communications again.Warren (WF0T) and I (Rob - K0XL) made a presentation about our Optical experiments at Aurora 2019. Warren made the same presentation at CSVHFS in July and at MUD in MUD in October of 2019..The presentations are available at https://sites.google.com/view/k0xl . Just scroll down past the more recent presentations.
One thing that might be of interest is the modulator which runs on an Arduino ATTiny85. It features an iambic keyer function for CW as well as an audio modulator for voice/music. It also has a beacon mode where the power is stepped down in -3dB steps for signal strength measurements. The schematic and code is available in the appendix section.
I think Warren has exceeded 10 miles (16km) for a QSO. The biggest problem we have in MN/WI is finding long line of site paths. At the end of the presentation, we outlined the possibility of testing a 50 km  (32mi) path from Duluth to a Wisconsin Park along the south shore. We also had some ideas about testing "Over the Horizon" paths considering the refraction of light in the atmosphere.
Maybe there will be enough interest to resume some of this activity :-)
See you all at Aurora 2025 June 7th.Rob - K0XL .

On Tue, Apr 15, 2025 at 12:10 AM Glen Overby <gpoverby at gmail.com> wrote:

They're using a receiver design by VE2UG, which is based on the one by KA7OEI and K0XL.  Transmit is a PWM generator they bought on Amazon.
I'm collecting parts for a system.
73, 
Glen
On Mon, Apr 14, 2025 at 11:14 AM Jon Platt via NLRS <nlrs at mailman.qth.net> wrote:

Some of us through the years have played with optical contacts.  Here is a link to W1VLFs YouTube video discussing and showing his 940 Nm 14 mile QSO.  The QSB and seeing the half power reduction testing is interesting.https://youtu.be/OXYJw9PyHd8
73, JonW0ZQ

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