Author Topic: High-Frequency Communications (Terahertz Radio)  (Read 3803 times)

Offline sanman

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High-Frequency Communications (Terahertz Radio)
« on: 11/08/2014 12:49 AM »
As part of a DARPA-funded project, Northrop-Grumman has created the world’s fastest solid-state amplifier circuit which can operate at frequencies of 1 Terahertz:

http://www.forbes.com/sites/eliseackerman/2014/11/03/darpas-terahertz-breakthrough-could-help-ease-spectrum-crunch/

http://www.spacedaily.com/reports/DARPA_Circuit_Achieves_Speeds_of_1_Trillion_Cycles_per_Second_Earns_Guinness_World_Record_999.html

What potential advantages might this type of technology offer for space-based communications?
Could something like this help a lunar or Mars rover send back streaming video to the Earth?

It seems like a given that the higher your frequency, the greater data-rate you can support.

I've read that laser-based communication has even higher frequency still, but on the other hand it probably has to be very precisely targeted between sender and receiver. Could terahertz radio span a gap by providing high-frequency, high-data-rate communication without requiring as extremely precise aiming as might be needed for laser communication?

Offline Robotbeat

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Re: High-Frequency Communications (Terahertz Radio)
« Reply #1 on: 11/08/2014 01:08 AM »
Terahertz /also/ needs to be tightly focused. Additionally, clouds and such interfere with it much like with laser light. Terahertz is similar to laser comms in those ways.
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Offline sanman

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Re: High-Frequency Communications (Terahertz Radio)
« Reply #2 on: 11/08/2014 01:22 AM »
Okay, so it may have problems in Earth's atmosphere, but in space, or on the Moon, or Mars, terahertz comms won't face that.

What about radar and sensory applications?

This article from IEEE says that terahertz rays (T-rays) can be used for spectroscopy as well:

http://spectrum.ieee.org/tech-talk/telecom/wireless/darpa-builds-first-terahertz-amplifier

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T-rays, as they’re known, also have the advantage of being able to penetrate many materials without using ionizing radiation, and to identify substances spectroscopically, which makes them suited to finding drugs, explosives, and pathogens.

So could T-rays be used to prospect for minerals, say in the asteroid belt for example?

I'm not sure what need there is for sub-millimeter radar-imaging in space applications. Are there any?

Offline Robotbeat

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Re: High-Frequency Communications (Terahertz Radio)
« Reply #3 on: 11/08/2014 01:56 AM »
Yeah, Terahertz stuff has lots of applications. But for comms, it's analogous to laser comms.
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Online Stormbringer

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Re: High-Frequency Communications (Terahertz Radio)
« Reply #4 on: 11/08/2014 03:57 AM »
Okay, so it may have problems in Earth's atmosphere, but in space, or on the Moon, or Mars, terahertz comms won't face that.

What about radar and sensory applications?

This article from IEEE says that terahertz rays (T-rays) can be used for spectroscopy as well:

http://spectrum.ieee.org/tech-talk/telecom/wireless/darpa-builds-first-terahertz-amplifier

Quote
T-rays, as they’re known, also have the advantage of being able to penetrate many materials without using ionizing radiation, and to identify substances spectroscopically, which makes them suited to finding drugs, explosives, and pathogens.

So could T-rays be used to prospect for minerals, say in the asteroid belt for example?

I'm not sure what need there is for sub-millimeter radar-imaging in space applications. Are there any?

T rays have many remote sensing applications. In fact it's basically the enabling technology for that tricorder everyone always wanted. the biggest basic hurdle to that was T rays were hard to make and if you did make them it required a huge bulky signal generator and receiver. but those hurdles have been overcome. They ( Thz signal generators and receivers) have been miniaturized to the point you could put a huge herd of them in a handheld device.
« Last Edit: 11/08/2014 03:58 AM by Stormbringer »
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Offline Proponent

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Re: High-Frequency Communications (Terahertz Radio)
« Reply #5 on: 11/08/2014 08:15 AM »
Terahertz /also/ needs to be tightly focused.

Why is tight focusing needed?  Is it because only low power levels have thus far been available?
« Last Edit: 11/08/2014 08:26 AM by Proponent »

Offline IRobot

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Re: High-Frequency Communications (Terahertz Radio)
« Reply #6 on: 11/08/2014 04:56 PM »
Some years ago I was involved in a project to evaluate the usage of Terahertz sensors for spectroscopy for automated fungus inspections on corks. At the time, a single spot sensor would cost around 150.000€. Eventually they became cheaper but they are still very expensive and hard to calibrate.
Still, their cost is not a problem for a spacecraft, but their cost for research for a final sensor assemblage is still high.

EDIT: that cost was high because of the specific frequency range within Terahertz.
« Last Edit: 11/08/2014 05:01 PM by IRobot »

Offline cordwainer

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Re: High-Frequency Communications (Terahertz Radio)
« Reply #7 on: 11/09/2014 10:28 PM »
Would a T-Ray receiver/transmitter be more energy efficient than a laser array for communications though?

Offline sghill

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Re: High-Frequency Communications (Terahertz Radio)
« Reply #8 on: 11/10/2014 05:43 PM »
As part of a DARPA-funded project, Northrop-Grumman has created the world’s fastest solid-state amplifier circuit which can operate at frequencies of 1 Terahertz:

http://www.forbes.com/sites/eliseackerman/2014/11/03/darpas-terahertz-breakthrough-could-help-ease-spectrum-crunch/

http://www.spacedaily.com/reports/DARPA_Circuit_Achieves_Speeds_of_1_Trillion_Cycles_per_Second_Earns_Guinness_World_Record_999.html

What potential advantages might this type of technology offer for space-based communications?
Could something like this help a lunar or Mars rover send back streaming video to the Earth?

It seems like a given that the higher your frequency, the greater data-rate you can support.

I've read that laser-based communication has even higher frequency still, but on the other hand it probably has to be very precisely targeted between sender and receiver. Could terahertz radio span a gap by providing high-frequency, high-data-rate communication without requiring as extremely precise aiming as might be needed for laser communication?

Having spent 8 years as a wireless data communications product developer, I'll throw in my $0.02.

I can see why DARPA would be interested in the technology.  It would have advantages over both laser and lower frequency radio communications for certain applications.  Notably, it would have the advantage of carrying more information per second than other radios, but it wouldn't have to be as tightly focused as a laser if the transmit distance is relatively short (say 50 miles).  This would be advantageous for high amounts of information transfer to and from moving objects (like drones or airplanes).  As information transfers gets larger (from drone applications in particular) because sensors and control systems get more complicated or have higher resolutions, this technology need also gets larger.

This radio would be most useful for C3 applications between a command ship or base and a sophisticated air drone that is relaying lots of information back to command while being controlled remotely- perhaps while engaged in combat.

Now, for space-based communications, I don't think there's an application here.  Space is wildly radio noisy, so a laser is preferable if you require high bandwidth communications, and with the distances involved in spaceflight a terahertz radio would have effectively the same narrow beam targeting limitations as a laser but without it's higher bandwidth and small size advantages- in a space application. 

And technological hurdles aside, what are you going to use high bandwidth communications for in space?  You only need the higher bandwidth if you are impatient for your data connection (i.e. you are trying to control something in real-time).  Once you get out past the moon, lasers don't offer much of an advantage other than compact size over existing radios because the latency is so high, and targeting becomes your primary technological hurdle.  Pretty photos can take their time downloading.

See also: http://en.wikipedia.org/wiki/Spectral_efficiency



Terahertz /also/ needs to be tightly focused. Additionally, clouds and such interfere with it much like with laser light. Terahertz is similar to laser comms in those ways.

Yes and no, power and attenuation of the frequency play a major role here.  A good laser comm system can go through miles and miles of clouds and ice fog (I used one for data backhaul from a foggy 1,000 meter peak at a distance of over 30km for years because it was cheaper than running fiber optic up there).  Also, the higher the power, the less backscattering problems a laser has to contend with.  Plus, depending on the color of the laser, water and water vapor might as well be transparent (I've got a friend who spent decades working on an air and space-based blue-green laser "sonar" system that effectively makes the oceans transparent.  It would have (may yet) negated any stealth warfare advantage by submarines).

As far as cloud attenuation goes (the ability of water molecules to absorb the power in the carrier wave) Some radio frequencies go right through clouds (like RADAR), while others get attenuated and transfer their power to the water (like a microwave oven).  2.4 Mhz makes a terrible carrier (which is why its unlicensed spectrum in most countries) while nearby 2.5 and 2.6Mhz are very valuable real estate precisely because they don't attenuate with water.
« Last Edit: 11/10/2014 07:17 PM by sghill »
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Offline Damon Hill

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Re: High-Frequency Communications (Terahertz Radio)
« Reply #9 on: 11/10/2014 05:47 PM »
I'm having a hard time visualizing a terahertz antenna that isn't basically optical, rather than electrically conductive dipoles.  For communications, one might as well go optical.

Online Stormbringer

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Re: High-Frequency Communications (Terahertz Radio)
« Reply #10 on: 11/13/2014 11:00 AM »
room temperature nano scale terahertz generator:

http://www.nanowerk.com/nanotechnology-news/newsid=38006.php

sooooo: tricorder!

EDIT: I am embarrassed. it seems this will not yet work at room temperature. but in the future it probably will.
« Last Edit: 11/13/2014 12:10 PM by Stormbringer »
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Online Stormbringer

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Re: High-Frequency Communications (Terahertz Radio)
« Reply #11 on: 11/21/2014 07:15 PM »
ok. here it is:  http://phys.org/news/2014-11-terahertz-device.html

room temperature thz scanner :)
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Online Stormbringer

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Re: High-Frequency Communications (Terahertz Radio)
« Reply #12 on: 10/23/2017 10:28 AM »
https://www.nextbigfuture.com/2017/10/making-wearable-mri.html

Sooo Tricorder! (again)

So anyway; you could turn your cell phone into an MRI scanner. i mean if they are discussing making them wearable like in a beanie or a glove or bondage gear or something you could totally put it in a cell phone.

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Offline as58

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Re: High-Frequency Communications (Terahertz Radio)
« Reply #13 on: 10/23/2017 06:18 PM »
I wish they didn't call it MRI, because its operating principle is nothing like MRI...

Online Stormbringer

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Re: High-Frequency Communications (Terahertz Radio)
« Reply #14 on: 10/23/2017 06:40 PM »
I wish they didn't call it MRI, because its operating principle is nothing like MRI...
Details, details... :)
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