Over the horizon on 481THz (optical)

Before my 2013 stroke I enjoyed experimenting at optical frequencies and was amazed that I could decode my QRSS CW well over the horizon with no clouds in the sky. Sadly, my stroke put an end to this. The circuit diagram shows the beacon I used. As you can see it is simple.

See https://sites.google.com/view/g3xbm4/home/optical-nanowaves/over-the-horizon .

2012 optical experiments

Way back in 2012 I was doing optical work at 481 THz. 

The photo shows some initial tests along the road at the old QTH. 

Later, some tests were done "over the horizon" non line-of-sight. I was astounded by the results.

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 .

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 .

Early 481THz experiments

This photo popped up as a Facebook memory today. 

It shows my early trials trying to receive my 481THz optical CW beacon in daylight along the road. As I recall, signals were very strong. Much much further was achieved later including over the horizon (NLOS). 

I guess this was 2012? The gear still exists and still works. It has not been used much since before my stroke.

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 .

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.

Phlatlights

In 2012, I bought several of these from the USA. My intention was to use these very powerful LEDs in my experiments with 481THz light communications over the horizon having had great success with QRSS over the horizon with far less powerful LEDs. 

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.

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 .

Nanowaves

As you will have seen, after a very long break, I took my first tentative steps back into optical communications yesterday. 

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.

See https://sites.google.com/site/g3xbmqrp3/optical

2021 481THz tests

It is about 7 years since I last tried anything on 481THz (red light). 

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.

481THz optical beacon

 

One of my Facebook memories today was this photo of my 481THz optical beacon. This was made in 2012 I think. 

I still have it and hope to use it again. It uses a K1EL keyer to produce either CW or QRSS. My first test is likely to be some sort of reflection test, possibly off trees.

It seems I like to experiment at the extreme ends of the spectrum, HI.  Either VLF (sub 9kHz) or optical comms (481THz)!

Optical Communications

It is many years since I tried any optical communications, because of my poor health:  I have been too giddy for field work.  

Hopefully, the next few weeks will allow me to do some local tests from home.

See https://sites.google.com/site/g3xbmqrp3/optical

Light wave communication

Yesterday I mentioned that some years ago I bought some Flatlights (very high power LEDs) to allow me to get further over the horizon with light beam communication. Even with quite low powered LEDs I was able to achieve quite decent ranges non-line-of-sight. 

Optical communications is accessible to all and is ideal for homebrewing. All my gear was homemade and all software was free. Also, only very simple test gear is needed. As I recall a multimeter and a bearly lit LED in a dark room is about all you need. This is much simpler than microwaves. 

There is so much to be learned about optical communications. My "thing" was detecting weak signals over the horizon using PC software. What amazed me was there was no sign of the light in the sky, yet the signals were perfectly detectable on the PC as long as the RX was aimed in the right direction. I am sure much further would have been possible.

See https://sites.google.com/site/g3xbmqrp3/optical

481THz experiments

Many years ago before my 2013 stroke I bought some Flatlights (very bright LEDs) from the USA to enable me to get further with my optical experiments over the horizon. Even with quite low power LEDs I had got way over the horizon. 

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.

Optical communications

Optical RX

Until my stroke in 2013, one of my joys was building and testing optical communications gear. Although I had a successful line-of site speech contact, my "thing" was weak signal communication over the horizon.

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

481THz speech communications

Long before my 2013 stroke, one of my favourite things was optical 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

481THz RX

Whilst looking through some old Google photos, I came across this one of my 481THz (optical) receiver. It was used in my "over the horizon" tests. It was also used in a line-of sight optical speech QSO over 11km with G4HJW.

I still have it and should try using it again.

Good optical comms site

On my own main website is some information (now very dated!) about my own experiments with optical communications at 481THz (red light). I was mainly interested in over the horizon, weak signal modes.

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

Optical DXing

Since my 2013 stroke I have not felt fit enough to do field work. I really miss my 481THz over the horizon NLOS (non line of sight) optical work.

Testing the optical kit

The results back in 2013 suggested much further would have been possible NLOS. All the gear was home made and the experiments were fun. Sadly I am just too wobbly these days.

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