8 Jan 2024
2012 optical experiments
28 Aug 2023
Optical Experiments
With very low power and simple, homemade, gear I could detect my beacon on a PC way over the horizon. In Australia, the "over-the-horizon" (NLOS) distance record is way over 100km. With my own very modest gear, I can well believe this.
My tests were done on cloudless nights, suggesting the propagation was scattering off atmospheric dust. There was no sign of the light from the TX in the sky at all. This is definitely where everyone, licenced or not, may experiment. It would be good to find out how far we could achieve non line of site (NLOS) in the UK. Incidentally LEDs are generally considered better than lasers due to scintillation (look it up!).
My own beacon and optical gear were made in the back of the garage. If I was fit, I would be experimenting now.
My optical gear used LEDs bought off eBay. Far more powerful ones are available. I used 100mm lenses used in magnifying glasses bought at Poundland. Better equipped stations used Fresnel lenses. My tripod was hopeless. With better LEDs, lenses and tripods, ranges could be increased a great deal. Even with my system ranges could be considerably greater than the nearly 9km I managed.
See https://sites.google.com/view/g3xbm4/home/optical-nanowaves/over-the-horizon.
31 Jul 2023
Optical communications - over the horizon
When fitter, I really enjoyed experimenting with this. Actually, I don't think this needs a licence at all, but it is real experimentation. Anyone can do this without costing much.
All my gear and much of my test gear was homemade and very inexpensive. It is real "back of the garage" stuff. All my gear was homemade in the back of the garage. The only special test gear was a very weakly lit LED. If you have a multi-meter and scope, you really don't need much else. In my view optical communications is easier than microwaves as the test equipment is easy.
I was quite surprised how easy it was to copy an optical signal "over the horizon".
See https://sites.google.com/view/g3xbm4/home/optical-nanowaves/over-the-horizon .
24 Apr 2023
Plans for Monday
My 481 THz test software and lead are my priority. When I did the optical tests way back more than 10 years ago PCs had separate mic and headphone jacks. All my PCs now have combined jacks!
So, I have to interface my optical RX and the PC in a new way. With soldering skills very hard these days, this requires some thought. Years ago I would just have bought a new jack socket (with mic input) and just changed the plug! I think years ago I just used a lead with standard 3.5mm plugs at each end.
I may put the 10m WSPR beacon on too.
UPDATE 1038z: 10m WSPR beacon is ON and my audio setup (interface from 481 THz RX to the PC) is working with Spectran. At G1KQH's suggestion I used a USB sound card I already had and it worked first time. Thanks for the suggestion Steve.
UPDATE 1144z: No 10m WSPR spots of my 500mW beacon. I suspect things are very disturbed. I checked all was well on another RX.
UPDATE 1515z: 4 stations have spotted me today so far on 10m WSPR. My 481 THz TX beacon and RX work with QRSS and Spectran.
14 Mar 2023
481THz optical beacon tests
This popped up as a Facebook memory yesterday. It is some years since I last did optical tests over the horizon. In the near future, I want to re-assemble my optical gear and do some local tests before attempting some NLOS tests with Bernie G4HJW who is over the horizon about 9km away.
6 Mar 2023
Upcoming optical tests on 481 THz
It is years since I did optical experiments. My current plan is to do some local tests with QRSS bouncing off buildings. If these are successful, I want to try an "over the horizon" test with G4HJW.
My first task will be to install Spectran 2 software as this will be needed to decode QRSS and to check the signal margins.
4 Feb 2023
8 Jan 2023
481 THz "over the horizon" communications
See https://sites.google.com/view/g3xbm4/home/optical-nanowaves/over-the-horizon for some ideas.
In many ways optical communications are easier than microwaves as all the gear (test gear and working kit) may be homemade at low cost.
The photo shows my first tentative steps in daylight along a road. Little did I realise what fun was to follow!
13 Nov 2022
Optical experiments
My optical tests were great fun. They all happened before my 2013 stroke. I can recommend optical experiments to anyone, as all the gear for use and testing was homemade easily in the back of the garage (literally).
If that darn stroke had no got in the way, I should probably still be doing optical tests today!
6 Oct 2022
Optical communications 2012
10 years ago I got 3 phlatlights from the USA with the intention of doing more "over the horizon" (NLOS) optical tests at 481 THz. Then my stroke got in the way. There are 3 in the drawer unused.
8 Mar 2022
Lightbeam communication
This was much easier than I thought.
Although my "thing" is NLOS (non line of sight) over the horizon digital comms, I have tried line of sight speech communications. People have managed much further than I have.
One of the beauties is the gear is all homemade. Even the test gear was homemade and simple.
See https://sites.google.com/view/g3xbm4/home/optical-nanowaves/line-of-sight .
12 Feb 2022
Optical experiments
In view of my earlier post, it is probably a good idea to point you to my pages on optical communications. I have not been able to do much in recent years because of my stroke, but there is nothing stopping others!
This is an area where the gear is easy, results can far exceed expectations and anyone can join in. As far as I know, no licence is needed.
All the gear uses low cost parts and can be assembled and tested in the back of the garage. Even test gear can be very simple and low cost. This really is great fun.
Some like to experiment with speech over very long distances. My "thing" was over the horizon. I was totally surprised that even when there was no sign at all of a signal, it could clearly be seen on a PC. The distance records for "over the horizon" are amazing. I think these used "cloud bounce", where signals are reflected off the base of clouds. In my case there were no clouds, so this was by refection off dust in the air I think.
See https://sites.google.com/view/g3xbm4/home/optical-nanowaves/over-the-horizon .
8 Jan 2022
Early 481THz experiments
28 Nov 2021
Optical communication webpage
In the past, I got lots of information from Clint KA7EOI's Optical Pages, that have many links. One of the most sensitive receivers by K3KCP was linked to from Clint's optical pages.
See https://sites.google.com/view/g3xbm4/home/optical-nanowaves/over-the-horizon .
13 Oct 2021
481THz test
OK, these are tiny steps. Yesterday I did a test reflecting my optical beacon from the kitchen, off the museum roof, to the RX in the lounge. I would guess the total path was only about 0.2km. The reflected signal was extremely strong, so I might try receiving the reflected signal at my son's house further away.
Unlike many years ago I am extremely giddy now. At one point the TX crashed to the floor. Luckily, nothing was broken.
I am just too wobbly for field work, but I want to do what I can. Receiving 10wpm CW at my son's house would be a great achievement for me nowadays.
7 Oct 2021
Phlatlights
Then I had my stroke and I was just too wobbly for field work. They are still in the shack drawer! It would be great to use these as I am sure much further non line-of-sight would be possible.
18 Sept 2021
Internet over free-space optical - NOT amateur radio
The BBC has an interesting piece about the use of free space optical communications to bridge the River Congo in Africa where optical fibre is impractical. This gives very high (not perfect) reliability and, in this case, is destined to carry internet traffic. Of course, this would not be suitable for places where fog is common, such as the bay area of San Francisco.
5 Sept 2021
Optical 481THz line of sight
It is some years since I seriously worked on optical communications. My main "thing" was over the horizon, so called non-line-of-sight (NLOS) beaconing. I was surprised that with very simple, homemade gear I could get well over the horizon, with no clouds to help. If my poor health had not got in the way, I am sure far greater ranges would have been possible. The record (in Australia I think) is an incredible distance.
I only had one speech contact over 11km line of sight and that was with G4HJW. All my gear was made in the back of the garage and it was very simple. The optics used low cost PVC drain pipes and the lenses were made from magnifying glasses obtained from a local Poundland store. The electrical gear was very simple and low cost. It was not worth making PCBs. Test gear is very simple. Optical experiments are low cost and fun.
My main G3XBM website has much more on my gear and experiments including NLOS tests.
See https://sites.google.com/view/g3xbm4/home/optical-nanowaves/line-of-sight .
19 Jun 2021
"Over the horizon" optical experiments
One of the things I enjoyed was experimenting with weak signal optical signalling over the horizon. My own tests used QRSS (slow CW) received on a PC . There was absolutely no sign of the optical signal in the sky, yet there was a clear trace visible on the PC.
Had I been well, these experiments would have continued and far greater ranges would have been possible.
See https://sites.google.com/view/g3xbm4/home/optical-nanowaves/over-the-horizon .
12 Feb 2021
2021 481THz tests
So, today I dug out my optical beacon TX and RX and tried some tests across the house. Although I could find the RX, my TX beacon took some finding! This is mains powered. I eventually found it in a cupboard and did some tests.
Tonight after dark, I shall try bouncing the signal off the windmill.
The last test I tried was in early 2014, but I was too wobbly.
Small steps.
UPDATE 2200z: I tried "windmill bounce" and "tree bounce" on CW at 10 wpm but it was too easy! Signals were very strong. One thing is clear: I am much more wobbly than I was 7-8 years ago. I'd like to try much greater obstructed paths with QRSS, but wonder if I am up to it these days.