8 Jan 2024
2012 optical experiments
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
20 Oct 2021
481THz line of sight
For the uninitiated, 481THz is red light.
My main interest in lightbeam communication was over the horizon beaconing (NLOS), but I did have one speech QSO line-of-sight over about 11km. As mentioned before, all my optical gear was homemade in the back of the garage. Most of the test gear was also homemade. In fact, optical gear is easier than microwaves and there are plenty of sources of ideas on the internet. My own page may trigger some ideas. The circuit above was used in the speech QSO.
See https://sites.google.com/view/g3xbm4/home/optical-nanowaves/line-of-sight .
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.
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 .
13 Feb 2021
Nanowaves
Before my stroke, I enjoyed going out in the field to see how far I could cover, especially over the horizon using QRSS (very slow CW) with PC decoders.
Much greater distances would have been possible, then my health got in the way. 😕
All the gear was home made. This was one of the attractions: all the gear was simple, including the test gear.
This is a field of experimentation open to everyone. You may find some ideas on my main website.
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.
29 Jan 2021
481THz optical beacon
One of my Facebook memories today was this photo of my 481THz optical beacon. This was made in 2012 I think.
It seems I like to experiment at the extreme ends of the spectrum, HI. Either VLF (sub 9kHz) or optical comms (481THz)!
16 Dec 2020
Optical Communications
Hopefully, the next few weeks will allow me to do some local tests from home.
7 Oct 2020
Light wave communication
6 Oct 2020
481THz experiments
Both my RX and optics could have been improved, so I was expecting much greater ranges. Then I had my stroke and I was unable to continue. To this day the Flatlights remain in the drawer unused.
5 Aug 2020
Optical communications
Optical RX |
Even without any visible signals in the sky I was able to detect my beacon from home on 481THz (red optical) way over the horizon, even though it was firing through double glazing. Had I been able to carry on, there were so many things I wanted to try including higher powerLEDs, further distances and a better tripod.
Sadly, these days I am too wobbly to do this portable work. As all the gear can be built and tested in the "back of a garage" with simple test gear, this could appeal to those interested in serious, but low cost, experimentation. Over the horizon optical work could do with attention.
See https://sites.google.com/site/g3xbmqrp3/optical
6 Apr 2020
481THz speech communications
Although my keenest interest was weak signal "over the horizon" signals, so called non line of sight (NLOS), I had one QSO with speech over a path of about 11km with G4HJW using the kit shown in the photo. Sadly my stroke put an end to my optical experiments.
See https://sites.google.com/site/g3xbmqrp3/optical
20 Nov 2019
15 Aug 2019
Good optical comms site
I was quite amazed to clearly detect my optical beacon over the horizon when nothing was visible in the sky. There were no clouds so I assume this was clear air scattering off dust particles. This was using QRSS3 and a PC to "see" the signal. My own experiments stopped shortly after my 2013 stroke. I did try one experiment out portable since, but I was too clumsy. I have not tried anything portable since 2014.
All the gear needed is quite simple to make and all the test gear needed easy to fabricate. I made a very weak signal source using a very very dim LED to test the receivers. This was mounted near the ceiling of a darkened room. With a good RX this should be received OK. If you cannot detect modulation on a very dim LED your RX is not good enough.
I still have all my optical kit. If anyone local wants to borrow it to carry on the experiments, I'd be very happy. They must be local as I will want the gear back.
Another good resource is http://www.modulatedlight.org/optical_comms/optical_index.html
30 May 2018
Optical DXing
Testing the optical kit |
It would be good to try infra-red frequencies. What amazed me was the total lack of a visible signal, yet perfect decode using QRSS3 on the PC on a very non line of sight path over the horizon.
See https://sites.google.com/site/g3xbmqrp3/optical
See also https://sites.google.com/site/g3xbmqrp3/optical/481thz-nlos
20 Apr 2018
Optical kit
All the optical kit was homemade and easy to assemble and test in the back of the garage with very basic test gear. Even the software used was free. Over the horizon testing with optical kit was challenging and great fun. Results amazed me.
See https://sites.google.com/site/g3xbmqrp3/optical