New 30THz video


Barry Chambers
 

Hi Folks

Bob, G4APV, and I are grateful to Peter, G3PHO, for putting together a video of our activities on 30THz over the past two months. It can be viewed here

30THz Further Adventures May June 2021 - YouTube

I hope you find it of interest.

73
Barry, G8AGN


militaryoperator
 

Hi Folks
Bob, G4APV, and I are grateful to Peter, G3PHO, for putting together a video of our activities on 30THz over the past two months. It can be viewed here
I hope you find it of interest.
73
Barry, G8AGN

I'm not getting it. Is it an actual "signal"? or just a version of a light/heat source being received  by a photocell. 
I must have missed the first days class. 
The Germans in WW2 had a voice comms unit using light. Lichtsprechgerät 80/80
Ben 


Glyn M0XGT
 

 
They’re using something like a Melexis MLX90614 thermopile detector in the long infra-red, a bit like the sort of thing you get in passive IR door openers and alarms, etc., and because the IR window is 5 to 14 um, where atmospheric absorption is low, it corresponds to at radio around 30 to 40 THz. 
 
It looks like fun, but it's just sending wideband thermal noise from an uncorrelated heat source, or sun heliograph, and detecting ON/OFF keying in the thermopile to claim 30 THz distance world records. But using a FLIR IR camera attachment on an iphone would likely work much better and also over a much longer distance. 
 
Gly M0XGT
 
 


militaryoperator
 


They’re using something like a Melexis MLX90614 thermopile detector in the long infra-red, a bit like the sort of thing you get in passive IR door openers and alarms, etc., and because the IR window is 5 to 14 um, where atmospheric absorption is low, it corresponds to at radio around 30 to 40 THz. 
 
It looks like fun, but it's just sending wideband thermal noise from an uncorrelated heat source, or sun heliograph, and detecting ON/OFF keying in the thermopile to claim 30 THz distance world records. But using a FLIR IR camera attachment on an iphone would likely work much better and also over a much longer distance. 
 
Gly M0XGT


Thanks Gly. There's a nice trick I found out using the tv remotes to check its battery. My digital camera can see the infrared led (I guess) but obviously not by eye. 

I wonder how far I could see the remote from?  I'll try it tomorrow, hi. 

Ben


Barry Chambers
 


They’re using something like a Melexis MLX90614 thermopile detector in the long infra-red, a bit like the sort of thing you get in passive IR door openers and alarms, etc., and because the IR window is 5 to 14 um, where atmospheric absorption is low, it corresponds to at radio around 30 to 40 THz.
 
It looks like fun, but it's just sending wideband thermal noise from an uncorrelated heat source, or sun heliograph, and detecting ON/OFF keying in the thermopile to claim 30 THz distance world records. But using a FLIR IR camera attachment on an iphone would likely work much better and also over a much longer distance.
 
Gly M0XGT

Gly,

I would be interested to hear how you get on with your FLIR approach. The fact that the FLIR sensor has many pixels to produce an image is of no advantage since you cannot combine the outputs of each pixel to produce a better S/N. Also, I suspect that the area of each FLIR pixel sensor is smaller than that of the single element Melexis sensor and so will not produce as much received signal power. Finally, my sensor is using the power received from a collecting area which is much bigger  than the lens of a FLIR camera attachment. Admittedly the surface of my 45cm receiving dish is by no means perfect at 30THz; neverthess the gain is still extremely large.



Thanks Gly. There's a nice trick I found out using the tv remotes to check its battery. My digital camera can see the infrared led (I guess) but obviously not by eye. 

I wonder how far I could see the remote from?  I'll try it tomorrow, hi. 

Ben

Ben,

Your TV remote will operate at around 850 - 950nm which corresponds to a frequency around 340THz. About ten years ago G0EWN, G0RPH  and I had contacts at these frequencies over distances  greater than 100km using high power LED emitters and inexpensive silicon detector diodes. 850nm works well but the atmosphere is becoming opaque at 900nm.

73

Barry, G8AGN




militaryoperator
 

Ben,
Your TV remote will operate at around 850 - 950nm which corresponds to a frequency around 340THz. About ten years ago G0EWN, G0RPH  and I had contacts at these frequencies over distances  greater than 100km using high power LED emitters and inexpensive silicon detector diodes. 850nm works well but the atmosphere is becoming opaque at 900nm.
73
Barry, G8AGN

Wow, thats amazing, 60 Mile with an led. Must have been a line of sight, mountain top to mountain top?

Ben


Neil Smith G4DBN
 

On 28/06/2021 09:07, militaryoperator via groups.io wrote:
Wow, thats amazing, 60 Mile with an led. Must have been a line of sight, mountain top to mountain top?


Hi Ben, the really nifty work with optical comms is cloudbounce and near line of sight using atmospheric dust as a scattering medium. Cloudbounce using an array of 60 or so lenses at the transmit end was used to get 288 km across the Tasman Strait by VK7MO and his chums.  https://www.amateurradio.com/tag/cloudbounce/

I have some foot-square Fresnel lenses and very high-power red LEDs, and there are quite a few ops with red-light gear. Red-sensitive Silicon Photomultipliers are available now which match the sort of focus spot size of a Fresnel lens.

For proper power on 30 THz, there are sub-£100 watercooled CO2 laser tubes of course, but you need a fairly fancy beam expander so you don't just cut a hole through the optics. Also, the kit is about as portable as an AR88.

There are stern limits on the use of optical lasers and high intensity LED beams as a result of idiots targeting aircraft pilots, with increasingly tight controls near to airports, and I guess even 10.64 micrometre radiation from those laser tubes would be subject to the same controls despite not being a risk to pilots.

The UKNanowaves IO group is the place to gather. Much like the sub9kHz and LF groups, you'll recognise some microwave op callsigns in there.

Neil G4DBN




militaryoperator
 

Hi Ben, the really nifty work with optical comms is cloudbounce and near line of sight using atmospheric dust as a scattering medium. Cloudbounce using an array of 60 or so lenses at the transmit end was used to get 288 km across the Tasman Strait by VK7MO and his chums.  https://www.amateurradio.com/tag/cloudbounce/
I have some foot-square Fresnel lenses and very high-power red LEDs, and there are quite a few ops with red-light gear. Red-sensitive Silicon Photomultipliers are available now which match the sort of focus spot size of a Fresnel lens.
For proper power on 30 THz, there are sub-£100 watercooled CO2 laser tubes of course, but you need a fairly fancy beam expander so you don't just cut a hole through the optics. Also, the kit is about as portable as an AR88.
There are stern limits on the use of optical lasers and high intensity LED beams as a result of idiots targeting aircraft pilots, with increasingly tight controls near to airports, and I guess even 10.64 micrometre radiation from those laser tubes would be subject to the same controls despite not being a risk to pilots.
The UKNanowaves IO group is the place to gather. Much like the sub9kHz and LF groups, you'll recognise some microwave op callsigns in there.
Neil G4DBN



OMG Neil, no, I have enough to think on now without getting a toe in there, hi.

About to start my Dremel special 9Cm filter constuction, hi. 

Ben


Barry Chambers
 

Ben

yes, we were working hilltop to hill top at 850nm.

Neil is correct about 30THz sources. Without deep pockets and appropriate safety precautions, the only other amateur source of 30THz radiation for DX is a source of heat, i.e. a heated metal plate or the Sun or even the Sun's radiation reflected or emitted off the Moon. I have made several heated plate emitters but there is a limit as to how hot and how big these can be made to give you a high EIRP at 30THz and also to be able to modulate the radiation, hence my interest now in using 30THz radiation from the Sun. For amateurs, there is also no advantage in trying to use a narrowband 30THz source since the readily available sensors are wideband - 1000s of GHz wide! So it makes sense to use a wideband IR source such as a heated object so as to fill the receive sensor bandwidth with signal power rather than just noise. Also, since the Melexis sensors exhibit best sensitivity with a slow response time - typically 1/2 sec, you cannot use normal speed CW. The other factor to consider is that every object emits IR radiation and this sets a limit to how well you can "see" a 30THz source when it is surrounded by other objects which themselves have been heated by the Sun, i.e. the QRM is a big problem!

Experimenting with 30THz requires a whole new way of thinking which is why it is fascinating. It still uses electromagnetic waves, so it's still "radio" but not as you know it!

73 Barry, G8AGN



On 28/06/2021 09:50, Neil Smith G4DBN wrote:
On 28/06/2021 09:07, militaryoperator via groups.io wrote:
Wow, thats amazing, 60 Mile with an led. Must have been a line of sight, mountain top to mountain top?


Hi Ben, the really nifty work with optical comms is cloudbounce and near line of sight using atmospheric dust as a scattering medium. Cloudbounce using an array of 60 or so lenses at the transmit end was used to get 288 km across the Tasman Strait by VK7MO and his chums.  https://www.amateurradio.com/tag/cloudbounce/

I have some foot-square Fresnel lenses and very high-power red LEDs, and there are quite a few ops with red-light gear. Red-sensitive Silicon Photomultipliers are available now which match the sort of focus spot size of a Fresnel lens.

For proper power on 30 THz, there are sub-£100 watercooled CO2 laser tubes of course, but you need a fairly fancy beam expander so you don't just cut a hole through the optics. Also, the kit is about as portable as an AR88.

There are stern limits on the use of optical lasers and high intensity LED beams as a result of idiots targeting aircraft pilots, with increasingly tight controls near to airports, and I guess even 10.64 micrometre radiation from those laser tubes would be subject to the same controls despite not being a risk to pilots.

The UKNanowaves IO group is the place to gather. Much like the sub9kHz and LF groups, you'll recognise some microwave op callsigns in there.

Neil G4DBN



-- 
73
Barry, G8AGN


Andy G4JNT
 

Sitting outside a deli in Winchester early on Saturday morning, I was being pleasantly warmed by the IR radiators - like patio heaters I guess -  they have installed for the benefit of their outdoor-seated guests.
The heaters look like over-powered dull light bulbs and are probably in the 500 - 1000W region.   They would be keyable for QRSS with  a faster response than your heated plate




On Mon, 28 Jun 2021 at 11:40, Barry Chambers <b.chambers@...> wrote:

Ben

yes, we were working hilltop to hill top at 850nm.

Neil is correct about 30THz sources. Without deep pockets and appropriate safety precautions, the only other amateur source of 30THz radiation for DX is a source of heat, i.e. a heated metal plate or the Sun or even the Sun's radiation reflected or emitted off the Moon. I have made several heated plate emitters but there is a limit as to how hot and how big these can be made to give you a high EIRP at 30THz and also to be able to modulate the radiation, hence my interest now in using 30THz radiation from the Sun. For amateurs, there is also no advantage in trying to use a narrowband 30THz source since the readily available sensors are wideband - 1000s of GHz wide! So it makes sense to use a wideband IR source such as a heated object so as to fill the receive sensor bandwidth with signal power rather than just noise. Also, since the Melexis sensors exhibit best sensitivity with a slow response time - typically 1/2 sec, you cannot use normal speed CW. The other factor to consider is that every object emits IR radiation and this sets a limit to how well you can "see" a 30THz source when it is surrounded by other objects which themselves have been heated by the Sun, i.e. the QRM is a big problem!

Experimenting with 30THz requires a whole new way of thinking which is why it is fascinating. It still uses electromagnetic waves, so it's still "radio" but not as you know it!

73 Barry, G8AGN



On 28/06/2021 09:50, Neil Smith G4DBN wrote:
On 28/06/2021 09:07, militaryoperator via groups.io wrote:
Wow, thats amazing, 60 Mile with an led. Must have been a line of sight, mountain top to mountain top?


Hi Ben, the really nifty work with optical comms is cloudbounce and near line of sight using atmospheric dust as a scattering medium. Cloudbounce using an array of 60 or so lenses at the transmit end was used to get 288 km across the Tasman Strait by VK7MO and his chums.  https://www.amateurradio.com/tag/cloudbounce/

I have some foot-square Fresnel lenses and very high-power red LEDs, and there are quite a few ops with red-light gear. Red-sensitive Silicon Photomultipliers are available now which match the sort of focus spot size of a Fresnel lens.

For proper power on 30 THz, there are sub-£100 watercooled CO2 laser tubes of course, but you need a fairly fancy beam expander so you don't just cut a hole through the optics. Also, the kit is about as portable as an AR88.

There are stern limits on the use of optical lasers and high intensity LED beams as a result of idiots targeting aircraft pilots, with increasingly tight controls near to airports, and I guess even 10.64 micrometre radiation from those laser tubes would be subject to the same controls despite not being a risk to pilots.

The UKNanowaves IO group is the place to gather. Much like the sub9kHz and LF groups, you'll recognise some microwave op callsigns in there.

Neil G4DBN



-- 
73
Barry, G8AGN


militaryoperator
 

Experimenting with 30THz requires a whole new way of thinking which is why it is fascinating. It still uses electromagnetic waves, so it's still "radio" but not as you know it!
73 Barry, G8AGN


Rather than rotate the hot plate why not have flaps in front, like a big Navy Signal light. You could then send CW a bit easier?.

US_Navy.jpg


Barry Chambers
 

Yes, this should work but I have yet to think of an easy way to make one which doesn't have too much "aperture" blockage in the "on" position.




On 28/06/2021 12:17, militaryoperator via groups.io wrote:
Experimenting with 30THz requires a whole new way of thinking which is why it is fascinating. It still uses electromagnetic waves, so it's still "radio" but not as you know it!
73 Barry, G8AGN


Rather than rotate the hot plate why not have flaps in front, like a big Navy Signal light. You could then send CW a bit easier?.

-- 
73
Barry, G8AGN


Barry Chambers
 

Hi Andy

a picture of the heater would be useful. I would guess that there might still be a problem with the thermal inertia of the bulb envelope?

Barry



On 28/06/2021 11:50, Andy G4JNT wrote:
Sitting outside a deli in Winchester early on Saturday morning, I was being pleasantly warmed by the IR radiators - like patio heaters I guess -  they have installed for the benefit of their outdoor-seated guests.
The heaters look like over-powered dull light bulbs and are probably in the 500 - 1000W region.   They would be keyable for QRSS with  a faster response than your heated plate




On Mon, 28 Jun 2021 at 11:40, Barry Chambers <b.chambers@...> wrote:

Ben

yes, we were working hilltop to hill top at 850nm.

Neil is correct about 30THz sources. Without deep pockets and appropriate safety precautions, the only other amateur source of 30THz radiation for DX is a source of heat, i.e. a heated metal plate or the Sun or even the Sun's radiation reflected or emitted off the Moon. I have made several heated plate emitters but there is a limit as to how hot and how big these can be made to give you a high EIRP at 30THz and also to be able to modulate the radiation, hence my interest now in using 30THz radiation from the Sun. For amateurs, there is also no advantage in trying to use a narrowband 30THz source since the readily available sensors are wideband - 1000s of GHz wide! So it makes sense to use a wideband IR source such as a heated object so as to fill the receive sensor bandwidth with signal power rather than just noise. Also, since the Melexis sensors exhibit best sensitivity with a slow response time - typically 1/2 sec, you cannot use normal speed CW. The other factor to consider is that every object emits IR radiation and this sets a limit to how well you can "see" a 30THz source when it is surrounded by other objects which themselves have been heated by the Sun, i.e. the QRM is a big problem!

Experimenting with 30THz requires a whole new way of thinking which is why it is fascinating. It still uses electromagnetic waves, so it's still "radio" but not as you know it!

73 Barry, G8AGN



On 28/06/2021 09:50, Neil Smith G4DBN wrote:
On 28/06/2021 09:07, militaryoperator via groups.io wrote:
Wow, thats amazing, 60 Mile with an led. Must have been a line of sight, mountain top to mountain top?


Hi Ben, the really nifty work with optical comms is cloudbounce and near line of sight using atmospheric dust as a scattering medium. Cloudbounce using an array of 60 or so lenses at the transmit end was used to get 288 km across the Tasman Strait by VK7MO and his chums.  https://www.amateurradio.com/tag/cloudbounce/

I have some foot-square Fresnel lenses and very high-power red LEDs, and there are quite a few ops with red-light gear. Red-sensitive Silicon Photomultipliers are available now which match the sort of focus spot size of a Fresnel lens.

For proper power on 30 THz, there are sub-£100 watercooled CO2 laser tubes of course, but you need a fairly fancy beam expander so you don't just cut a hole through the optics. Also, the kit is about as portable as an AR88.

There are stern limits on the use of optical lasers and high intensity LED beams as a result of idiots targeting aircraft pilots, with increasingly tight controls near to airports, and I guess even 10.64 micrometre radiation from those laser tubes would be subject to the same controls despite not being a risk to pilots.

The UKNanowaves IO group is the place to gather. Much like the sub9kHz and LF groups, you'll recognise some microwave op callsigns in there.

Neil G4DBN



-- 
73
Barry, G8AGN
-- 
73
Barry, G8AGN