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Showing posts with label Light Beam Telephony. Show all posts
Showing posts with label Light Beam Telephony. Show all posts

Thursday, May 16, 2024

A Light-beam QSO in Hollandia, Christmas 1944


This old QST article caught my eye, largely because my father was also in Hollandia on that  Christmas day in 1944.  He was in the Navy hospital there, recovering from wounds received in the battle of Leyte gulf (in the Philippines).   Hollandia, also known at Humbolt Bay, is now Jayapura, Indonesia. The picture above shows the harbor in 1944.  Rod Newkirk W9BRD went on to write QST's inspirtional "How's DX?" column for many years. 
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From S/Sgt. R. H. Newkirk, W9BRD, "Christmas, 1944" QST, January 1946, pages 25 and 102.

Christmas, 1944


In a wartime world the singular and exclusive camaraderie that exists in the hobby of amateur radio results in so many unexpected and coincidental meetings between good friends, who have previously never seen each other, as to make such happenstance fairly commonplace. But I boast a tale in which time, place and circumstance combined to cause a similar occurrence to be most extraordinary.

The Liberty ship El Segundo Ruiz Belvis lay at anchor in the murky waters of Humbolt Bay, New Guinea, on a tepid tropical night in '44. In the absence of the moon, the Dipper and the Southern Cross scintillated bewitchingly. On the shore, the lights of the army base of Hollandia burned steadily in contrast to the varipowered signal blinkers which intermittently pieced the opaque darkness throughout the harbor. The latter were visual communication between ships and shore plus an admixture of ship-to-ship chatter, official and otherwise. There was an underlying tense tinge to the atmosphere and the stillness was broken only by the sharp staccato of the Belvis' blinker shutters as the signalman transacted port business with the powerful land station.

This was rendezvous. Our Liberty, with scores of army personnel aboard, had here become a unit in the formation of a huge convoy. Crammed into holds, on hatches and into every available nook and cranny of the steel deck, we were Leyte-bound. Stifled, sweaty and hungry on our two meals per day, we wore out deck after deck of pinochle cards and read every available piece of literature over and over again. It was almost a month since we had left Sansapor, scene of our last operation. We were exuberant in the knowledge that we were soon to leave New Guinea.

Christmas was but a few days away and we had had no mail for weeks. Men leaned languidly on the rail and thought of home while others dreamed of the same in their cramped quarters. The circumstances certainly made this Yuletide one to be long remembered. Nevertheless, all that would feature this day for us would be a possible piece of priceless turkey added to the usual dehydrated viands. Just another dragging equatorial day to be piled atop hundreds of others like it.

It was ten o'clock. I was wide awake; only my eyes were tired. Presently, I found myself detachedly reading the blinkers which poked their focused fingers indiscriminately about the bay. My quarters, in the cab of a 399, were on the port rail amidships and afforded a good view across the water. I became absorbed in various bits of chatter between nearby vessels. It struck me that QRM was quite heavy tonight—a sort of an optical 80 meters. I saw one of the lights sign off with a "73." This was interesting as among the host of merchant marine signalmen, hams are spread pretty thinly. I seized my M-1 torch and focused an insipid beam in the direction of that ship. I sent CQ CQ CQ K. A ham call sign is a cumbersome thing to handle with a blinker. Furthermore, I had no faith in the DX powers of my 3-volt flashlight bulb. I was therefore elated when a bright interrogatory sign beamed forth, aimed obviously in my direction. Contact! True, it was outside the hambands, but band divisions in the microwave region are indefinite anyway.

I was still dubious as to whether my man was an amateur. Rather than complicate matters immediately, at this speed of 8 words per minute, I began in the language of the layman: HELLO PAL WHERE YOU FROM? K. Back in an agreeably rhythmic style came: R TULSA OKLA NAME IS HAL K. The given name and place struck a subconscious inner chord vaguely. Next, I blinked: GE HAL IM ROD FROM CHGO K. There was a pause. He reoriented his beam to compensate for tidal drift and then startled me with: W9BRD DE W5EGA K.

The night quickly took on an exhilarant aspect as we lapsed into ham vernacular, spiced with many Morse slaps on the back. Hal Frank was no other than an old c.w. crony of mine. We had heckled each other on 80, 40 and 20 a countless number of times in the prewar days. In memory I was hearing again that beautiful swing and T9X sledge-hammer signal off his three-element rotary. We discovered mutual ham friends and we exchanged much welcome information and recounted bygone days. He was quite amazed to learn that I was behind a mere GI flashlight (with low batteries at that). The QSO continued far into the night—the next and the next.

We seemed destined to rot in our anchorage. The convoy movement was postponed from day to day. However, this Christmas season took on a much different aspect for me as arrangements were made and, at 0900 Christmas Day, my friend, Wilbur Kuure, W9YNY, and I debarked unsteadily down the ladder and made our way across an undulating swell to the Liberty ship Chittenden. There, we met Lt. Hal Frank, W5EGA, personally, for the first time. We all agreed that it was quite a small and bizarre world that December 25th.

Verbal reminiscences cluttered the air within W5EGA's exceedingly neat cabin for several hours. Shelves in his quarters were lined with excellent reading material including many late QSTs. Compared to our situation aboard the Belvis, Kuure and I thought this a bit of heaven.

We were thoroughly acquainted by the time we appeared in the officers' mess. As the cuisine took shape before us and disappeared into our eager gullets, my army pal and I felt somewhat sorry for our less fortunate buddies on the home ship. But such is life. We had, in nautical terms, a "Little Roundhouse," consisting of a generous helping of everything on the menu. We swept our plates clean to Hal's amusement. I remember, most distinctly, the dessert of apple pie and ice cream.

Nightfall found Kuure and me "back to earth" on the Belvis after a most delightful Christmas Day. According to plan, we blinked a "goodnight and thank you" to W5EGA through the twilight. That was our last QSO of that series. Not long after that we weighed anchor and headed for our next stop on the long road back home. Our holiday was over, a new year had begun and there was still a war to be won.


From S/Sgt. R. H. Newkirk, W9BRD, "Christmas, 1944" QST, January 1946, pages 25 and 102.

Saturday, September 1, 2018

Lasers. Big Scary Lasers. And a guy with THE KNACK



Here is another young fellow who shows all the signs of having "The Knack." I think his findings would be very useful for those involved in light beam communication. 

Sunday, March 13, 2016

Another Lightwave Communication Knack Story from the UK





Hi Bill,

I've been following your podcast since you started and enjoy every episode. I've been licensed here in Scotland since 1970 as GM8EUG.

I thought you/others might be interested in how I got into radio/electronics and how I feel I may have the 'Knack'. 

The above reference reminded me of some experiments I carried out in 1967 as a schoolboy. There were no ready sources of parts locally for me.. I lived  in a rural area so the nearest electronics parts shop was 50 miles away so it was all done by letter and mail order.

My first audio link was driven by a tube broadcast receiver with a 3 volt torch bulb connected instead of the loudspeaker. (I hadn't heard of impedance matching!)  This flickered nicely on speech/music peaks. The bulb was positioned at the focal point of a parabolic car headlamp reflector from a scrap car.  I now had a beam of light with audio on it.
Next step was the receive side...I didnt have access to a photo cell but had a Cadmium Sulphide photo resistor. Connecting a pair of low impedance headphone in series with this cell and a 1.5 volt battery gave me recognisable audio when the cell was in the beam...no amplifier needed!

Next step was greater range...this was achieved with a 6 inch shaving mirror to focus the beam onto the photo resistor. This gave me the length of the street (100 yards when it was dark outside )with the flickering beam shone out of my schoolboy bedroom window resulting in puzzled  looks from passers by.

Next problem was the frequency response.. all bass and no treble. Some research indicated that the photo resistor had a slow response so that was part of the problem but I had a hunch... How fast does a filament bulb react to audio? Biasing the bulb with a 1.5 volt cell so that it glowed  dimly with no audio improved the audio response greatly.

So what got me into radio...my father was a Chief Radio Officer in the Merchant Navy during WWII and my schoolboy bedtime reading (the only technical stuff I could find ) was his textbook ...the 1939 edition of the Admiralty Handbook of Wireless Telegraphy. Capacitors  were called condensers and they were measured in 'jars'!

That was the start of a career. I've now moved through testing international telephone exchanges, installing 2 way radio for the whole of Scotland for British Rail (paid for my hobby!) and finally 32 years in IBM writing manufacturing test software from the original IBM PC to Thinkpads.
Now retired I am active on WSPR and am writing Android apps to keep my brain in gear.

I just can't leave this stuff alone!

Hope this of interest/amusement.

73s

Neil Roberson GM8EUG




Friday, March 4, 2016

That Time We Were Re-Transmitted on 487 THz On a Red Light over Salt Lake City....


Some of you may remember this from back in 2012:

http://soldersmoke.blogspot.com/2012/09/soldersmoke-in-red-light-zone.html

Fast forward to November of last year. By this time I'd forgotten about the Utah light beams.  Ron Jones, K7RJ, was kind enough to send me a wonder-filled bag of electronic parts.   I have been slowly sorting them.  All kinds of great stuff is in there, but I noticed a lot of stuff that you don't normally find in ham shacks -- lots of optical stuff, lots of LEDs and photo transistors, little transistors with lenses on the top.  Cool stuff all, but not the kind of parts you'd use for a 40 meter CW rig.  What the heck was Ron building?  I wrote and asked.  Here is his reply. 


I’m like you, Bill, I’m a jack of all trades and master of none. I dabble in this and that. I always have a hand full of half finished projects on the bench.

 The optical stuff probably fell on the floor when Clint (KA7OEI) and I were experimenting with “through the air light communication” a few years back. Clint in the real guru in that particular project. We made optical contacts over what we think is a world record – 173 miles! That meant packing in optical gear to the top of remote Utah mountains, but what a great time we had!  We used a high power LED – NOT a laser. Lasers really suck for super long range communications. They are great for wide band across a parking lot, but not for voice communication over tens of miles (in our cast 173 miles) over the  air. We did over 100 miles with a laser pointer – can you believe that? A $3.00 laser that you torture your dog with… 100 miles!  But, that is a different topic. If you do say anything about the optical stuff, be sure to mention Clint, he really engineered the optical communication project.

By far, most important thing that we did with optical communication was on one of our short tests (only about 50 miles) when we broadcast one of the Solder Smoke episodes for anyone who cared to “look in” on our red beacon.  I think Clint sent you a picture from his side of the path a few years ago.
 
If there are any parts in that pile of junk that you are particularly interested in, I may be able to find more data and/or circuit ideas I had. But, honestly, a lot of that is stuff that is as strange and wonderful to me as it is to you. Fun as heck to look at, but needs to be put in the “YAFP” pile (Yet another .. project). 
 
Thanks for doing the podcast. It is always an inspiration for me to keep my soldering hot. 
 
73
Ron K7RJ 

Very cool.  So Ron had been at the other end of Clint's Red Light beam, the light beam that was carrying a SolderSmoke podcast across Salt Lake City.   And it appears that some of the parts involved in that amazing project have ended up in my junk box.  The Radio Gods like this sort of thing and may have been at work here.   Thanks Ron. 

Sunday, December 20, 2015

SolderSmoke Podcast #183 Pete's B'day, Simple-Ceivers, Binaural Bliss, 160 or Bust, GOOD BEHAVIOR, MAILBAG

Bill's Frankenstein R2 receives 7 MHz signal and generates I and Q outputs

SolderSmoke Podcast #183 is available. And it is GOOD!

http://soldersmoke.com/soldersmoke183.mp3

20 December 2015

-- Foxes in the Backyard
-- Pete completes another orbit
-- Simple-ceiver Success!
-- Frankenstein Receiver: IT IS ALIVE!  AND BINAURAL!!!
-- 160 Meter AM OR BUST!
-- Fun on 40 AM -- Lots of Multi Elmac AF-67s!  Who knew!
-- The Amateur's Code, and violations thereof.
-- Negative Frequencies? I don't think so.
-- Capacitor Offer from our Secret Benefactor: EXPANDED ELIGIBILITY
-- Projects for 2016: Pete goes Raspberry Pi, Bill goes DX-100
Mailbag:
-- Croation Creation
-- Salvadoran 2B
-- N3FJZ's Homebrew QSL
-- WA7HRG's LBS-ZIA-Simple-Ceiver Mashup Rig
-- KC0IZR turning VCRs into Mighty Mites in NOVA
-- AB1YK Starting with DC RX, going BITX
-- G8GNR puts Mighty Mite on AM!
-- G3ZPF Modulates THE SUN (Amazing)
-- VK3YE's Simple Superhet
-- Grayson in Turkey drools over KG7TR's Octalmania
-- N7REP reaches for the Zantac because of Arduinos and Surface Mount
       

Sunday, November 29, 2015

More on Light Beam Telephony


Hi Bill,

Reading about the Photophone and modulating the Sun experiments by G3ZPF reminded me of my own schooldays when as a final year physics project I think in 1970, I and another pupil built a light modulated telephone based on a design published in Practical Wireless of June 1970 by J. Thornton Lawrence. For the optical system it used a pair of spherical mirrors from old projection televisions. The detector was the expensive (for a school kid) OCP71 photo transistor, though we did also try ordinary less expensive OC71 transistors with the black paint scraped off with less success.
As David G3ZPF noted the problem with filament bulbs was the thermal inertia, and as I found it was also possible for the filament to mechanically resonate in the wooden box and start to howl. As we had never heard of, nor could have afforded an LED, we tried a Neon bulb run from an HT battery and modulated with a transformer in series with it. I recall coupling up a broadcast radio as the audio source playing "My Sweet Lord" by George Harrison and receiving it at the other end of the physics corridor very loud and clear on the audio amplifier on our light telephone receiver, much to the consternation and annoyance of the other teachers in the adjacent classrooms.

I found my black and white photo of the light telephone gear, complete with carbon telephone microphone that we used. It did work a fairly good distance in daylight outside across the school playground, not just the couple of feet shown. Also attached are photos of the original magazine cover and index, but regrettably not the article itself.

This was all before I got my ham ticket, but I already was a SWL and had been exposed to a wonderful ham, Tom GM3OWI (Oh Wild Indians) who visited the school and demonstrated all sorts of neat stuff like lighting a bulb from the output of a transmitter, and also voice modulating a klystron 3cm transmitter that the school had for doing electromagnetic radiation experiments, like polarisation, reflection etc.

Come to think of it, we got to play with a lot of stuff at school in those days which would never be allowed now, mercury, radioactive sources, alpha, beta and gamma, X-Ray and UV.  The museum in Edinburgh also had a science area with similar stuff you could play with, and get great shocks from the Van der Graff generator if you put your hand on the glass cabinet and touched the adjacent metal radiator!

Happy days!

73 David Anderson GM4JJJ

Saturday, November 28, 2015

Photophone! Modulating the Sun by G3ZPF (and Alexander Graham Bell, and Mr. A.C. Brown of London)


Yesterday David G3ZPF sent us another very interesting e-mail, this one about some very creative sunlight communication experimenting that he and his brother did many years ago.  It appears to me that David -- on his own -- came up with a version of Alexander Graham Bell's Photophone (pictured above). 

Wikipedia says that Bell's invention was the first ever wireless telephony device.   Bell credited Mr. A.C. Brown of London for the first demonstration of speech transmission by light (in 1878).  

Here is the Wikipedia article: https://en.wikipedia.org/wiki/Photophone 

I think young David's placement of the small mirror on the cone of the AF amplifier's loudspeaker was brilliant! 


Hello again Bill,

Just (literally) finished the book and a couple of surprises awaited me in the final chapters

SSDRA = $200 on Ebay
My flabber has never been so ghasted....and I have a lot of flabber. I will treat my copy with even more reverence now. Srtangely I hadn't heard about EMRFD so I'll need to look into that

Modulating light
Your story about using a laser pen in a receiver reminded me of my method of modulating light which I've never seen anyone else mention.

In the mid 60's my brother had an electronics constructor set for his birthday. After the initial fascination I probably played with it more than him. I remember reading about modulated light transmitters and (because this was before I was anywhere near getting a licence) I decided to build one. My brother was sufficiently curious to help.

We started with the receiver. I purchased an OCP71 and managed to find an old 12" headlight reflector from somewhere. The cork from a wine bottle fitted nicely into the hole at the centre, and the cork was easily drilled out to accommodate the photo-transistor.

My brother constructed the "high gain audio amplifier" project from his constructor kit and we put two legs of the photo transistor across the mic input. We were rewarded by a buzzing sound so loud our parents yelled at us from the other room. It took us a few seconds to realise we were 'receiving' the 50Hz signal off the ceiling light (the house lights were on). Waving the headlight reflector around confirmed this. I still recall the excitement we felt at our 'discovery'.

So far, so ordinary, but the TX side is where I wandered off into the outfield. Normally people modulated an incandescent bulb but this required a many watts of audio power & the 'inertia' of the filament could be a problem.

I cannot remember what prompted me to do this, but next day I pulled the speaker grill off my tiny little medium wave transistor radio and glued a small mirror (from my mothers old 'compact') to the cone of the loudspeaker.

Then we went outside into a field near our house. My brother went to the far end and I set up the lil radio on a camping stool. Moving it around until the sunlight reflected off the mirror hit the headlight reflector about 200 yards away.

Then I turned on the radio. Instantly my brother started jumping up and down excitedly. It worked. My 200mW AF amp was modulating the *SUN* !

All those guys on 160m with their 10w of AM...pah. I had GIGAwatts of power under my control :-)

Looking from the receive end it was possible to see the light from the mirror flickering & I guess the movement of the speaker cone did not move the mirror exactly in the plane of the reflected beam. The 'wobble' fooled the phototransistor into seeing an amplitude modulated beam.

The beauty of this was that only a tiny audio amp was needed. This made me wonder about such a system being used in undeveloped countries (ones with more sunshine) as a comms system, with batteries recharged by the sun.

For the UK I thought about using a slide projector to provide the illumination, instead of the sun. Again a very low power audio amp was all that was needed, and there were no 'inertia' issues to worry about it.

But I was soon to suffer a setback. A few days later the headlamp reflector, sitting on a desk in my bedroom, managed to find itself in a position to focus the suns rays onto the cork holding the photo-transistor. Cooking the transistor & setting fire to the cork. Luckily my mother smelt the burning cork before any collateral damage was caused but I had a face-chewing when I came home from school.

I'd long since forgotten about all this until reading the later chapters of your book.

regards

David G3ZPF










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