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DIY Texting System For Really Underground Radio

timothy posted more than 4 years ago | from the nitpickers-will-come-out-of-their-caves-now dept.

Communications 98

Gulthek writes "Sixteen-year-old Alexander Kendrick has created a device that allows texting and other data transfer from almost 1000 feet underground. The tech could allow rapid emergency communication with the surface and opens the potential for scientific measurements without the need to continually visit (and disturb) the cave environment." There's some kvetching in the NPR story's comments that it's not the first use of cave radios, but that seems to miss the point.

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Pesky child... (0)

Goldberg's Pants (139800) | more than 4 years ago | (#30973892)

Damnable overachievers...

Re:Pesky child... (-1, Flamebait)

Anonymous Coward | more than 4 years ago | (#30974234)

Summary:

Gulthek writes...There's some kvetching in the NPR story's comments...

Kike detected. The Jews own all media.

Re:Pesky child... (0)

Anonymous Coward | more than 4 years ago | (#30978570)

The Jews own all media.

Oh, that's just what the Illuminati wants you to think!

Re:Pesky child... (1)

Proteus Child (535173) | more than 4 years ago | (#30981570)

So, what are you doing? Besides looking down on someone who actually got off their ass and did something cool, I mean.

Living with Mom (1)

nacturation (646836) | more than 4 years ago | (#30973942)

I guess Mom's basement goes really deep underground for this guy. Perfect technology for nerds everywhere! Why risk your pasty white skin getting outdoors to text?

Re:Living with Mom (3, Insightful)

jimbolauski (882977) | more than 4 years ago | (#30976286)

Why risk your pasty white skin getting outdoors to text?

What nerd doesn't have wifi and a wifi enabled phone.

Re:Living with Mom (1)

joeme1 (959209) | more than 4 years ago | (#30978252)

this one :( any donations? This nerd is raising a family and going to school while only working 30 hours a week so he can take a pay cut to become a teacher.

This doesn't just apply to caving I expect. (3, Insightful)

Anonymous Coward | more than 4 years ago | (#30973984)

This doesn't just apply to caving, it should work as well for mining no? Range shouldn't be an issue since if it uses radio then relays should be feasible.

Re:This doesn't just apply to caving I expect. (1)

wizardforce (1005805) | more than 4 years ago | (#30974314)

Also submarine communications. The trouble is that the bandwidth is very very low.

Re:This doesn't just apply to caving I expect. (2, Insightful)

Darkness404 (1287218) | more than 4 years ago | (#30974586)

Even with low bandwidth, a simple message of "Hey, I'm still alive down here, send help" shouldn't be too hard.

Re:This doesn't just apply to caving I expect. (0)

Anonymous Coward | more than 4 years ago | (#30975182)

Please, let us with an internet diploma in efficiency make the efficiency related remarks; how about "alive,help,"... you could've typed that 5 times in the time it took you to write what you wrote. You'd be dead by now!
Or then again... it's quite obvious you were alive so you could just remove that part.. and while we're at it, let's go with "SOS"... and encode in 7bit ascii.

Re:This doesn't just apply to caving I expect. (0)

Anonymous Coward | more than 4 years ago | (#30975654)

Wouldn't just plain CW do it much easier? . . . _ _ _ . . .

Remember the ham radio operators who used CW were faster than the kids texting on the Jay Leno Show?

Or maybe doing it digitally has some special significance. Just seems to introduce a much more complicated setup. As people have been using these frequencies for years, I don't see the advantage of this.

btw, the captcha for this was "transmit" :-)

Re:This doesn't just apply to caving I expect. (1)

MidnighToker (890097) | more than 4 years ago | (#30976932)

CW is fantastic, but RTTY has a couple of advantages that I can see. 1) RTTY has a larger character set than CW, so although slow and bandwith restricted (over low frequency) it would be easier to send "data" over the link. 2) It absolves the user from having to learn anything, which is a requirement for modern society. Rather than having to learn Morse code 'i jus typ in dis box &pres snd lols!' So sadly not easier, as CW requires learning :(

Re:This doesn't just apply to caving I expect. (4, Informative)

ndege (12658) | more than 4 years ago | (#30977832)

I am giving up the mod points from this thread by posting, but thought you might be interested in something else:

Forget both CW and RTTY. Use PSK31 [wikipedia.org] . It uses less RF frequency bandwidth than CW and is a quite common modulation on HF (low frequencies such as 1.838.15 MHz/160meters) right now.

There is also a version that includes error correction: QPSK

Here is a comparison between RTTY and PSK31: http://www.arrl.org/tis/info/HTML/psk31/index.html [arrl.org]

PSK31 uses 16 times less transmit power than a CW station.

The difference between a CW filter of 500 Hz and the bandwidth of PSK31 of 31 Hz (10*log(500/31) db = 12 db) is 12 db, which demonstrates that a CW transmitter must transmit 16 times more power than a PSK31 transmitter to achieve the same signal to noise ratio. Therefore, a PSK31 station can operate at 16 times less power than a CW station.

Cite: http://www.larkfield.org/pdf/psk31.pdf [larkfield.org]

There is also a slower implementation that is less prone to interference; these versions operate at 10 and 5 baud (PSK10 and PSK05, respectively). Seems very slow, but for simple critical communications, there are fast enough.

Here is what PSK31 sounds like: http://en.wikipedia.org/wiki/File:PSK31_sample.ogg [wikipedia.org]

Ran across PSK31 a few months ago and was fascinated by the ingenious insight put forth in the specification.

Just thought you might want to know...

Apples and oranges. (1)

dtmos (447842) | more than 4 years ago | (#30978992)

I think you'll find that CW has a signal bandwidth equal to or less than that of PSK31, when sent at the same data rate. If you doubt the textbooks, this is easy to see for yourself, by having someone send CW while you look at the signal on the waterfall display of your favorite PSK receiving software -- or just tune down to the CW portion of the band and have a look.

People often use filter bandwidths of 500 Hz (or even more) while manually receiving CW, just for ease of tuning, and let their brains do the "channel filtering" to separate individual CW signals present in that bandwidth. Similarly, people often use filter bandwidths of 2.4 kHz when receiving PSK31, just for ease of tuning, then let their computer do the "channel filtering" to separate the individual PSK signals present in that bandwidth.

You're comparing the signal bandwidth of PSK31, with the noise bandwidth of a CW receiver. The two are separate concepts.

Re:Apples and oranges. (1)

ndege (12658) | more than 4 years ago | (#31004296)

Interesting insight! Thanks for pointing that out.

Re:This doesn't just apply to caving I expect. (2, Funny)

goldaryn (834427) | more than 4 years ago | (#30975880)

Even with low bandwidth, a simple message of "Hey, I'm still alive down here, send help" shouldn't be too hard.

That's what she said.

Yes, my "bandwidth" is "low"

Re:This doesn't just apply to caving I expect. (0)

Anonymous Coward | more than 4 years ago | (#30976510)

Yeah, but AT&T will still charge about 10 times what it would cost to just use it to make a phone call.

Re:This doesn't just apply to caving I expect. (2, Interesting)

electrostatic (1185487) | more than 4 years ago | (#30974644)

The Navy shore VLF/LF transmitter facilities transmit a 50 baud submarine command and control broadcast which is the backbone of the submarine broadcast system.

More at http://www.fas.org/man/dod-101/navy/docs/scmp/part07.htm [fas.org]

Re:This doesn't just apply to caving I expect. (3, Interesting)

SaffronMiner (973257) | more than 4 years ago | (#30976242)

No one has yet answered the Coal Mining Location Challenge: http://www.wearablesmartsensors.com/location_challenge.html [wearablesmartsensors.com] The is a much harder problem to solve than most people think, as explained at the link. The first thought is always "Use GPS". GPS does not work underground... etc. Range is an issue because Coal absorbs most radio waves. There are also limitations are power due to Intrinsic Safety Regulations.

Re:This doesn't just apply to caving I expect. (1)

wealthychef (584778) | more than 4 years ago | (#30976446)

Well, if more power is the answer, then change the regulations. Saying "regulations are the limit" seems weird.

Re:This doesn't just apply to caving I expect. (2, Informative)

solafide (845228) | more than 4 years ago | (#30977030)

There's this thing called marcasite. It is often found with coal deposits, and is extremely flammable at temperature/pressure similar to that at the Earth's surface. Guess what a radio wave potentially exciting marcasite because it's overpowered will do --- it'll set the marcasite on fire, and as a result the whole coal bed. It's _intrinsic_ to coal mining, it's like breaking the gravitational laws --- you shouldn't try it.

Re:This doesn't just apply to caving I expect. (1)

wealthychef (584778) | more than 4 years ago | (#30977280)

OK, then the reason for low power is that it's dangerous, not because there is a regulation. I was just saying, the reason given originally for not using more power was "due to regulations."

Re:This doesn't just apply to caving I expect. (0)

Anonymous Coward | more than 4 years ago | (#30978062)

Your problem is that you failed to think hmm maybe its a safety regulation.. let me guess republican?

Re:This doesn't just apply to caving I expect. (1)

Artifakt (700173) | more than 4 years ago | (#30978306)

No, his 'problem' is he recognizes there are good and bad regulations, so saying 'it's because there's a regulation' is relatively meaningless, while explaining the actual root cause is much more meaningful.

Re:This doesn't just apply to caving I expect. (1)

wealthychef (584778) | more than 4 years ago | (#30981398)

Exactly. I don't give a crap if there are 40 regulations. To assume that regulators know what they are doing ignores a lot of evidence to the contrary. OTOH, as AC pointed out, it's good to know why the dumbshits in charge made the rule I'm about to break.

Re:This doesn't just apply to caving I expect. (2, Interesting)

RockDoctor (15477) | more than 4 years ago | (#30979454)

OK, then the reason for low power is that it's dangerous, not because there is a regulation.

This may come as a shock, but some regulations are actually based on chemical reality. In this case, the purpose of "IS" designs of sensors, communication systems, etc, is to restrict the amount of energy in a hazardous area to below the amount that can produce a spark in an explosive hydrogen-air mixture. (I can't remember if it's at LEL or UEL, but WTF - it's still around 20 micro-Joules if I recall correctly). Systems that are designed an installed to IS regulations can be run much more simply than other systems, which we typically called "power" systems. The differences are non-trivial - you need to use single or doubly-armoured cables, solid-walled conduit etc etc. They're a lot more bloody complex to install.

Why would this affect an emergency response system? I hear you ask? Because it is not a good idea to deal with a roof-collapse by turning it into a roof-collapse plus a gas explosion.

You're not the first person to get into confusion about this. The last time I was paying attention, the UK emergency services were being pressurised to use a single, common radio system. A fine and laudable idea, but the fire brigade pointed out that the systems being proposed were not designed to be non-sparking. Un-surprisingly, firefighters did not relish the idea of going into (for example) a gas leak investigation with a radio set that might produce a spark.

Re:This doesn't just apply to caving I expect. (1)

DerekLyons (302214) | more than 4 years ago | (#30978170)

No one has yet answered the Coal Mining Location Challenge: http://www.wearablesmartsensors.com/location_challenge.html [wearablesmartsensors.com]

I doubt anyone has really tried. The 'challenge' is on an obscure website, the 'challenger' cannot clearly be indentified, and the bits about 'pseudo science merely being science a few years ahead of the mainstream' are just weird.

Lights Out (-1, Offtopic)

Eminor (455350) | more than 4 years ago | (#30974016)

Lights Out guerilla radio
turn that shit up

Ultra narrow bandwidth (2, Insightful)

stox (131684) | more than 4 years ago | (#30974074)

Reduce your bit rate to a few bits per second, even fractional bits per second, and you will be amazed at how far you can get a signal with a minimum of power.

Re:Ultra narrow bandwidth (1)

thatskinnyguy (1129515) | more than 4 years ago | (#30974524)

Narrow beamwidth with the same power does that.

Re:Ultra narrow bandwidth (4, Funny)

pclminion (145572) | more than 4 years ago | (#30974646)

By Jove you're right, we'll certainly have no problems aligning the transmitter and receiver through solid rock

Re:Ultra narrow bandwidth (1)

ehrichweiss (706417) | more than 4 years ago | (#30974724)

I guess that they hadn't thought of signal strength meters, homing tones, etc.?

Re:Ultra narrow bandwidth (1)

pclminion (145572) | more than 4 years ago | (#30975536)

By Jove you're right, we certainly have the time for that when involved in an emergency rescue -- why worry about whether his leg will have to be amputated, we need to align these god damned antennas

Re:Ultra narrow bandwidth (0)

Anonymous Coward | more than 4 years ago | (#30976714)

I guess that they hadn't thought of signal strength meters, homing tones, etc.?

Bandwidth |= beamwidth.

The article's more interesting point is buried (4, Insightful)

JoshuaZ (1134087) | more than 4 years ago | (#30974154)

The article also talks about how this could be used by scientists who are investigating or monitoring life in caves and that this could be used to help find useful substances being made by life in the caves. From the article:

But scientists think one of the biggest threats to this emerging source of antibiotics is actually the scientists themselves. In fact, researchers believe the more they visit a cave, the less likely they are to find antibiotics. People contaminate the sensitive cave environment just by being there. Northup thinks that by connecting data recorders to Kendrick's radio, scientists could remotely transmit information about the cave environment. "So a cave radio that allows you to beam data to the surface rather than visiting it in person can be extremely valuable," she says. "It could save the cave."

Frankly, this doesn't seem that likely since to check if something is a useful antibiotic it needs to be tested against actual cultures generally. However, this does have serious potential of helping and of increasing our knowledge base. General medical knowledge and more anti-biotics will likely save far more lives than using the technology just to rescue people who occasionally get trapped in caves.

Re:The article's more interesting point is buried (1)

Genda (560240) | more than 4 years ago | (#30978464)

Actually you could do "bio-assays on a chip", style testing, and simply send back the results of those tests... even pass no-pass tests could be very useful, at which point your robot could take a few dozen well chosen samples back up top for further analysis. Such assays could allow you to do hundreds or even thousands of simple tests, and you could use a relatively small robot (or a robot with great ability to move through small spaces like a snake-bot) so your access to places people can't even go, could prove especially useful. All in all, this is a great development for scientists and communication from underground.

Oh, and just following up on the prior thought, a Snake-bot could also contain the large wire loops necessary to transmit to the surface.

Underground radio in the 60's (5, Interesting)

Jerry (6400) | more than 4 years ago | (#30974168)

I recall reading a story a few years ago about some protesters at Berkely using audio amplifiers to transmit information between their various members and groups. They'd attach the ground lead of the audio output of a 200 watt audio amp to a 10-15' rod pounded into the ground. The positive lead was attached to another, shorter rod, pounded into the ground several feet away. To recieve, they'd switch the wires from the ouput to the input of the audio amp. The claim was that they could send voice as an electrical wave several miles. Don't know how true the story is, but it sounds like it might work.

In central Nebraska, not far from Silver Creek, is a "Survivable Low Frequency Communications System" The wiki writes about it: http://en.wikipedia.org/wiki/Survivable_Low_Frequency_Communications_System/>
"SLFCS single channel, receive only capability is provided at ICBM launch control centers. The single channel operates between 14 kHz and 60 kHz to receive commands from remotely located Combat Operations Center - Transmit/Receive (T/R) sites; this low frequency range is slightly affected by nuclear blasts.". The signal travels along and underneath the ground, i.e., Ground Wave propagation. Because the frequency was close the the 60 Hz power line frequency the two 1 KHz side tones were used to track power line faults.

When I drove by the Sliver Creek antenna and tuned my radio below 550 Khz I could find a hetrodyne signal and listen to the characters being transmitted in 5X5 blocks of characters.

Re:Underground radio in the 60's (1)

John Hasler (414242) | more than 4 years ago | (#30975168)

> The signal travels along and underneath the ground, i.e., Ground Wave > propagation. Ground wave [wikipedia.org] does not travel beneath the ground.

The Boy Mechanic (2, Informative)

westlake (615356) | more than 4 years ago | (#30975380)

The claim was that they could send voice as an electrical wave several miles. Don't know how true the story is, but it sounds like it might work.

Of course it will work.

Morse used earth conduction to bridge the Susquehanna River in 1842-3. CALLING ALL NATIONS -- 1941 [privateline.com]

Kids were taking on projects like this in 1913. How To Make A Wireless Telephone [chestofbooks.com]

Very Low Frequency (VLF) Stations [smeter.net] [2010]
  Ham Radio below 9 kHz [www.qru.de] [2006?]

Sounds familiar (0)

Anonymous Coward | more than 4 years ago | (#30974214)

It sounds a bit like ELF. The problem with really low frequencies is you can't transmit large amounts of data and they require larger antennas. The military's ELF arrays are massive and are only good for launch codes. That's the reason he's talking about text messaging. A smaller antenna like he's holding could take a considerable amount of time to transmit even a paragraph of information. It might be okay for scientific equipment but I doubt it'll be practical for much else. There's nothing earth shattering here, it's been done at least since Tesla's time. The reason it was never pursed is there are practical limits and minimal commercial value in the technology.

Finally (4, Informative)

Junior J. Junior III (192702) | more than 4 years ago | (#30974230)

No more out of range problems while I'm in my mom's basement.

Re:Finally (0)

Anonymous Coward | more than 4 years ago | (#30974866)

If you're 1000 feet underground, then you're probably in your mom's dungeon, not her basement.

What that says about your mom... well, I will leave that to your own imagination

Re:Finally (1)

arndawg (1468629) | more than 4 years ago | (#30979272)

He's in his basement. But in practice it is like he is 1000 feet underground. But only when his mom is home.

Re:Finally (0)

Anonymous Coward | more than 4 years ago | (#30975118)

You mean your evil overlord underground lair, right?

Cave Rescue (3, Informative)

HarleyCanuck (616646) | more than 4 years ago | (#30974270)

"In a 1991 New Mexico cave rescue, it took 170 people four days to save a woman with a broken leg. The rescue team had to lay miles of telephone line in order to stay in touch with the surface." "If they'd had Kendrick's radio, the rescue time may have been cut in half." When we go caving, especially a new one, or a rescue, Who wastes time laying phone wire? Teams are two, each with a different colour string with a wire core for added strength. This way we can follow different pipes simultaneously if its a complex cave. If two can get them out we do. Otherwise one stays one goes back. With all the gear we have who wants to be carrying all this stuff. If it can be made smaller the better. I guess my point is more about the Mexico rescue thing. Cool Idea kid!

Re:Cave Rescue (5, Informative)

Anonymous Coward | more than 4 years ago | (#30974650)

I do cave rescue, so I have some insights.

The first problem is that unless encrypted, radio communications are not secure. We don't necessarily want the press snooping in on radio chatter, which might include things like if the patient has died- then it shows up on the TV news before the family finds out in a less public fashion. That's not very popular with rescuers.

The second problem is that communications aren't always 100% in this fashion; based on the cave radio work that I've been part of, it can be pretty sketchy. We're doing the same things as Alexander- and he's doing great work, no argument- but it's not exactly new stuff. Hard-wire communications aren't always 100%, either, but they tend to be more reliable. Maybe radio will exceed that someday.

The Emily Mobely rescue would probably have taken about 100 hours with radio, same as it did with hard-wire communications. She was in a bad spot when she broke her leg, and Lech is a technically challenging cave- long hauls without a lot of space to work, that kind of thing. Because of Emily, people who have been injured in Lech have "self-rescued." Only a severe, debilitating accident that immobilized a patient would be cause for such a large, intensive rescue as hers.

Re:Cave Rescue (1)

FiloEleven (602040) | more than 4 years ago | (#30985280)

You've been in Lechuguilla Cave? That's fantastic and I'm jealous!

For those who don't know, a lot of the footage from Planet Earth: Caves was shot there. Here's a clip [youtube.com] . It is, I think, the deepest known cave in the US and has some completely unique rock formations. Unlike most limestone caves, this one was carved from the bottom up by sulfuric acid. Due to the delicacy of the cave environment, the Planet Earth crew is probably the last film crew to be allowed access. They did a great job of showing off the variety of formations found there.

I have loved caves since I was a kid, but I've only been to two that aren't show caves--there's not a whole lot of 'em in southeastern PA. The one I frequent, located in Pequea Valley, has a few decent-sized rooms and an unexplored (and tight!) cleft that I've wanted to go further down, but I need to find someone else as skinny as I am to join me.

Re:Cave Rescue/Emily (0)

Anonymous Coward | more than 4 years ago | (#30976378)

Ah, Emily, a real nice gal.

Several of my Caving friends were involved in her "rescue".

My sweety and I gave her a party at our house on the one year anniversary of her rescue [people.com] .

I had been exploring the Fubar Passage in nearly the same spot in Lech where the rock peeled away from the wall and almost crunched her (breaking her leg) [youtube.com] on an expedition six months before, I had a narrow escape with a BIG rock peeling from the wall there as well.

Sooo (0)

Anonymous Coward | more than 4 years ago | (#30974284)

who wants to start the first underground filesharing railroad

What am I missing here? (2, Informative)

westlake (615356) | more than 4 years ago | (#30974556)

Developed by Los Alamos National Laboratory, the Through-The-Earth Communication system proved capable of sending two-way, very-low-frequency (VLF) voice signals from the surface of the mine to depths exceeding 300 feet at the experimental mine operated by the National Institute for Occupational Safety and Health (NIOSH).

The Through-The-Earth Communication system was developed for the U.S. Department of Energy at Los Alamos National Laboratory's Superconductivity Technology Center with a development team led by David Reagor. The technology has also earned a prestigious R&D 100 Award from R&D magazine.

The system uses VLF electromagnetic radiation in the range of 3 to 30 kilohertz (kHz) and digital audio compression to transmit wireless voice and data signals through the earth. Materials that block higher radio frequency (RF) signals, such as rock, concrete, metal, and high-density ore bodies, do not restrict its signal

Incorporating Sprint/Nextel i325 mobile phones, supported by Raytheon's JPS Communications ACU 1000 cross-band repeaters, the Through-The-Earth Communication system demonstrated its capabilities in the Lake Lynn Mine, which is composed of several long tunnels used for mine safety experiments. The mine consists of nonflammable limestone with a tunnel height of about 10 feet and an overburden of up to 370 feet. Test Of Through-The-Earth Communication System Exceeds Expectations [wirelessne...online.com] [August 2007]

VLF appeals to radio hobbyists because of its exotic associations with both natural science and submarine warfare. To get started all you really need is a PC and a home-made antenna. Radio Waves Below 22 Hz [www.vlf.it]

Re:What am I missing here? (0)

Anonymous Coward | more than 4 years ago | (#30974626)

Yep, played with it some myself back in the 90's. It's fun but the antennas are the Achilles's heal (also power requirements, somewhat) and this kid's design has the same issue.

Re:What am I missing here? (0)

Anonymous Coward | more than 4 years ago | (#30992678)

add to this http://www.minesite.com.au/coal_mines_ped_systemc

I've sat half way down Aquamole Aven (4, Interesting)

alanw (1822) | more than 4 years ago | (#30974622)

for half an hour with a transmitter waiting for my friends on the surface to radio-locate the position on the surface vertically above me.

The transmitter fits in a 6 inch diameter tube - you'd never get an antenna like the one in the photo down a Yorkshire cave. The one used on the surface is much bigger, though.

The next project is to produce a cheap transmitter that a cave diver can carry into an aven and leave (they don't want to have to hang around), in the hope that once located a dig can be done from the surface directly above.

Here's a links to a UK cave radio web site
http://caves.org.uk/radio/ [caves.org.uk]

Re:I've sat half way down Aquamole Aven (1)

Herriott101 (1142499) | more than 4 years ago | (#30975086)

I agree, it seems way too big and unwieldy to go caving with. Especially for UK and Alpine caving. Something like the System Nicola cave radio would be better. It's small, lightweight and fits into a small peli case, making it perfect for caving and cave diving. Although, I'm not sure if they're in production yet. Here's the only site I could find with information on it (although it does get a bit technical as it's aimed for DIY hobbyists): http://naylorgr.perso.cegetel.net/cave_radio/ [cegetel.net]

Re:I've sat half way down Aquamole Aven (1)

adrianturner (1734410) | more than 4 years ago | (#30976512)

The System Nicola Mk 2 has been in operation for a good many years in the south of France, and now the designer, Graham Naylor, is pressing on with a completely digital version, the Mk3. UK Cave Rescue Teams have been using the Heyphone [bcra.org.uk] since 2001. In 2004, Beat Heeb designed [bcra.org.uk] a mobile phone sized device for sending and receiving text messages underground. Both the Nicola Mk 2 and the "mobile texter" have ranges of ~1000m, I can't remember what the operating range of the Heyphone is.

Re:I've sat half way down Aquamole Aven (1)

Dare nMc (468959) | more than 4 years ago | (#30977340)

you'd never get an antenna like the one in the photo down a Yorkshire cave.

FYI the antenna as transported was several short sections of PVC and a roll of wire. I have a hard time imaging a cave that is navigable by people that couldn't somehow shove say 1 meter sections of PVC into. If your saying the caves never expands to a size greater than a 2m diameter cube, then I agree they couldn't set it up.

Re:I've sat half way down Aquamole Aven (1)

alanw (1822) | more than 4 years ago | (#30978108)

Whilst there are places which open up, the part of the cave we wanted to locate was a lot less than 2m wide and high.

Re:I've sat half way down Aquamole Aven (0)

Anonymous Coward | more than 4 years ago | (#30978404)

that a cave diver can carry into an aven

Not even google knows what an "aven" is. The dictionary, wikipedia, google, etc.
WTF is an aven?

Re:I've sat half way down Aquamole Aven (1)

alanw (1822) | more than 4 years ago | (#30984198)

http://www.speleogenesis.info/glossary/glossary_by_letter.php?Authors=a [speleogenesis.info]

1. A hole in the roof of a cave passage that may be either a rather large blind roof pocket or a tributary inlet shaft into the cave system. A feature described as an aven when seen from below may equally be described as shaft when seen from above, and the naming of such a feature commonly depends purely upon the direction of exploration.

Aquamole Aven, as its name suggests, was discovered by cave divers who then
climbed upwards until they could join up with a surface dig .

As I mentioned, one of the uses of cave radio is to locate the point vertically above on the surface.

The etymology of "aven" (1)

silverspell (1556765) | more than 4 years ago | (#30984414)

I was curious too, so:

"Aven" is a French loanword, though it doesn't show up in my little French dictionary, or in the Oxford English Dictionary for that matter. But I found a French-language online dictionary that basically says it's a natural well ("puits") found in limestone. Apparently it's a loanword in French as well, taken from the Rouergat (?) dialect of the Occitan language.

I glanced at a few English-language caving publications which translate "aven" as "big cavern", "cathedral", "sinkhole", "shaft", or "abyss". (That last one seems a little suspect, since there's already a French word for "abyss", abîme.)

Confusingly, a lot of these words have water-related cognates. "Aven" apparently also means "river" in Breton, and in English a "puit" can be a well or a stream.

(Disclaimer: IANA linguist.)

Why was it so warm? (0)

Anonymous Coward | more than 4 years ago | (#30974624)

Anyone else notice that the guy said it was 68 degrees 1000 feet underground? With that much open air to the surface, it's not surprising he could get a radio transmission through.

Re:Why was it so warm? (1)

Big Bob the Finder (714285) | more than 4 years ago | (#30975604)

The temperature in caves (which are typically a few hundred feet deep) is close to the temperature of land, averaged over many years. In the northeast, caves are 50-55F, while in the southwest they are typically in the 60s and 70s. The part that Alexander was in is a very deep part of the cave; it's not a matter of "open air to the surface" that the temperature is that warm. It's simply how the cave is in southeastern New Mexico, where it gets frickin' hot in the summer, but never very cold in the winter.

From where he was, it's not possible that the cave served as a waveguide for the RF. And as best as I know, there's no metal in that part of the caves- electrical lines or metal handrails, as there are in the tourist parts of the cave- that would allow the transfer of RF energy.

so this is the bin laden comm system? (1)

Joe The Dragon (967727) | more than 4 years ago | (#30974718)

so this is the bin laden comm system?

Then what is the point? (5, Insightful)

SuperBanana (662181) | more than 4 years ago | (#30974758)

Well, what is the point, then?

VLF systems have been in use for decades to communicate with the US Submarine fleet, not because of interference, but because it passes through just about everything and has a very, very wide propagation. Unfortunately, the power levels are so high that people wonder/suspect it's causing nature / health problems for nearby residents.

I mean for fucks' sakes, this stuff was in use by the German navy during WW2- 70 years ago. All this kid did was apply the obvious, and apparently, it's so obvious, someone thought of it 40 years ago. More info:

http://en.wikipedia.org/wiki/Very_low_frequency

Also, the kid didn't implement any sort of retransmission or error correction. That makes it pretty useless for both emergencies (imagine: "person has 3 hours to live" instead of "30 hours") and scientific data collection. It's also pretty standard these days.

Re:Then what is the point? (0)

Anonymous Coward | more than 4 years ago | (#30975070)

Also, the kid didn't implement any sort of retransmission or error correction. That makes it pretty useless for both emergencies (imagine: "person has 3 hours to live" instead of "30 hours") and scientific data collection. It's also pretty standard these days.

Great idea. Waste a lot of time on gee-gaws that could be added in later before you even see if the basic idea works.

Remember when Ford retooled all his factories to build flying cars? Oh wait...

Re:Then what is the point? (1)

gandhi_2 (1108023) | more than 4 years ago | (#30975724)

the kid didn't implement any sort of retransmission or error correction

No kidding, if only there was some sort of layered protocol scheme whereby some facilities could be implemented at various other layers.

Re:Then what is the point? (1)

SaffronMiner (973257) | more than 4 years ago | (#30976336)

I mean for fucks' sakes, this stuff was in use by the German navy during WW2- 70 years ago. All this kid did was apply the obvious, and apparently, it's so obvious, someone thought of it 40 years ago.

This stuff was used in World War One:

http://www.rexresearch.com/rogers/1rogers.htm [rexresearch.com]

James H. ROGERS

Underground & Underwater Radio

( Static-free Reception & Transmission Underwater & Underground )

Re:Then what is the point? (0)

Anonymous Coward | more than 4 years ago | (#31001394)

(imagine: "person has 3 hours to live" instead of "30 hours")

Yeah, I'm sure no one would think of repeating anything critical like numbers.

Perspective of an actual caver-geek (5, Informative)

Like2Byte (542992) | more than 4 years ago | (#30975068)

First. I applaud this guy for making such a neat device. Listening to the story break on NPR this morning was rather captivating. The reporter made the device sound relatively small - something able to fit easily within a single cave-bag after disassembly. After seeing the antenna array, though, I thought my eyes would pop out of my head. There is no *way* a group of cavers are going to carry this contraption around *as it is*. It is certainly a prototype and the device certainly has merit but, for the sake of the device and the caver(s) carrying it, it is hoped (at least by me) that it becomes a lot smaller and still able to transmit/receive with the surface counterpart.

You see, a device as large as the one in the pictures on the webpage would be unwieldy in many, if not most, caves in the US as most US caves are not walking passage. In its current form it would suffer a lot of abuse and probably become submerged in water, covered in cave mud, bumped, sat on, kinked, bent, folded, dropped, hoisted, scraped and buffeted from a normal days wear and tear. If the antenna wire itself became broken trouble would certainly ensue. So, I don't see the current form of cave rescue going away any time soon. (The cave-trip leader has a designated person that did NOT go on the cave trip to call by a certain time. If the trip leader has not called that person by that time a cave rescue is supposed to be carried out.)

Don't get me wrong - this is a very cave-worthy pursuit and many a caver would feel better about having this technology along for the trip - as long as the equipment could withstand the journey. Otherwise, it's just more dead weight.

Second. For the story itself - caving is not 'relatively safe.' It's more along the lines of relatively dangerous. Why? Anyone entering a cave with the attitude of 'relatively safe' is bound to get hurt. Very recently there have been people who went out for a day of caving and came back sans one member. See this story [cbs5.com]

I didn't know this guy but it seems arrogance killed him. Hate me for it if you have to but he went into a passage where 2 other people had to be rescued from years earlier. It's shameful that the cave owners/grotto overseeing the cave didn't have the foresight or fortitude to prevent future tragedies by closing that passage or making the cavers sign a form detailing that particular passage as off-limits. He died a slow death as hypothermia set in while he was upside down in a passage. He was supposed to be experienced. I heard about his story while he was still alive and I prayed that he could hold on long enough for a solution to extricate him could be found. I'm heartbroken and angry for his needless death.

Thirdly. One part of the radio broadcast that this story didn't relay is a story of the famous (or is it infamous) rescue of Emily Davis Mobley from Lechuguilla Cave very near Carlsbad, New Mexico. I think the broadcast mentioned that this (the Lechuguilla cave rescue) was the reason why he invented this device. (I remind you to see the above paragraph on caving being relatively safe. Still think so?)

You Tube of the rescue: http://www.youtube.com/watch?v=J7I7bXcSWK8 [youtube.com]
Wikipedia Entry: http://en.wikipedia.org/wiki/Cave_rescue [wikipedia.org]

Fourth. If you want to know more about caving visit Emily's website: http://www.speleobooks.com/ [speleobooks.com]

Finally: If you still don't believe me that caving is dangerous just you try cave diving. Near 100% fatality rate where 'accidents' have occurred. The rule of thumb is is something goes wrong while cave diving - you have two minutes to live.

Here's the official website for caving accidents in the Americas - http://www.caves.org/pub/aca/ [caves.org]

FYI, There's NO FN WAY you'd get me to cave dive.

Re:Perspective of an actual caver-geek (1)

drinkypoo (153816) | more than 4 years ago | (#30977006)

I'm heartbroken and angry for his needless death.

Angry I can understand; what an inconvenience for the rest of you! But heartbroken? This guy is a Darwin award nominee at best.

so what you're saying is (1)

circletimessquare (444983) | more than 4 years ago | (#30978834)

caving is relatively safe

(sorry, couldn't resist)

my dad was an avid spelunker before i was born. thank god/darwin he kept the relative danger to a minimum, or i wouldn't be here

Re:Perspective of an actual caver-geek (1)

jc79 (1683494) | more than 4 years ago | (#30981568)

I didn't know this guy but it seems arrogance killed him. Hate me for it if you have to but he went into a passage where 2 other people had to be rescued from years earlier. It's shameful that the cave owners/grotto overseeing the cave didn't have the foresight or fortitude to prevent future tragedies by closing that passage or making the cavers sign a form detailing that particular passage as off-limits

I'm a professional outdoor activities instructor, and I've had friends who've died while participating recreationally in the sports they love. It's an accepted part of what we do. Surely it's up to an individual to assess the risks themselves and make judgements on what they consider acceptable. Why should the cave owners be considered responsible for someone's safety? "Volenti non fit injuria" - ie if you know the risks and do it anyway, you've only yourself to blame when you get hurt..

I'm not a caver,. but I assume in the US, information about particular caves is disseminated through the community on much the same way as in the UK (guidebooks, internet etc). It should be easy enough to find out before entering a cave if a certain passage is dangerous or not. It shouldn't be up to the cave owners to require everyone to sign a form or modify the cave to prevent people choosing to go that way.

Re:Perspective of an actual caver-geek (1)

Like2Byte (542992) | more than 4 years ago | (#30985020)

You know. That's a good perspective and one I take at whatever I do.

This entire discussion pertains to 'wild caves' - not commercial caves.

Caves in the US are largely kept 'under wraps' - cavers don't discuss caves with non-cavers for fear of someone attempting to spelunk while not having a clue as to what they are doing. How it works in most grottos in the US is that the new caver comes to a few meetings so the group can gauge whether or not the new guy (or gal) is simply someone looking for thrills or to steal artifacts/cave formations from the cave - a federal offence in the US. Most cavers are fairly responsible cave stewards.

The problem arises when individuals go into caves clueless and wonder why they're injured, stuck, hurt or lost. People have gotten lost in caves and have actually successfully sued the land owner even though the land owner directly forbid or was unaware that people were entering a cave on his property. These are the same people who ignored the 'no trespassing' signs posted all over the property.

Information pertaining to a particular cave is not disseminated throughout the local community. I'm not sure on just how much of the UK is made up of soluble rock so caves can be formed but the US is so broad that entire states don't have a single cave to their name. Therefore, caves are not in the collective forefront of communities minds. Maybe in the TAG area of the US (Tennessee, Alabama, Georgia) they do as the TAG area has loads of caves. Maybe there are communities are more enlightened as it pertains to cave locations but I seriously doubt it. There are a handful of cave locations that do have public information pertaining to the cave - to gain entrance to those caves the person must contact the grotto currently stewarding that cave. Caves like this are usually set up on a rotational schedule so no one grotto gets burnt out stewarding that particular cave.

Here's one: http://www.necaveconservancy.org/preserves/clarksville_preserve.php [necaveconservancy.org]
See the pool of water on this page? At the bottom most edge (from our 2d perspective) of this pool of water someone drowned - his SCUBA gear prevented him from getting to the surface a mere six feet below. All the while his buddies waited above.

While information pertaining to some caves does indeed exist on the Internet, most information is not widely known. Most grottos within a karst region keep the location of caves held tightly to their chest for reasons I've explained above. Even if cave maps were readily available, reading real cave maps is not a trivial task. By the time some spelunker (not a caver) got into a situation it'd be far too late for a map to be of any use for them anyway. Spelunkers, IMNSHO, are the kind of people who don't give a rats ass about anyone else's safety or don't think of their own safety until they're in a situation.

That's why cavers have a saying about spelunkers: "Cavers rescue spelunkers."

Cavers in the US also try to maintain a high degree of conduct WRT cave owners - we want to be able to go back. We keep a dialog open with the cave owner and abide by his/her wishes as to cave-entry requirements for his/her cave. (ie: camping overnight prohibited or not). A lot of times, the choice of whether to allow cavers (or anyone, for that matter) to enter their cave is solely up to the land owner. One of the driving factors of his/her allowance to let cavers in is based upon how well he trusts the legalese on the cave entrance form most cavers must sign in order to gain entry.

And that's the way it is. Very few cave owners approve their caves for entrance without the consent form being signed by every member of the caving party.

After having said all that, I'd be very surprised if any caver sued a land owner for getting hurt in the cave they were exploring. however, if little 10 year old Johnny and friends come along and get stuck in the cave how sure are you that your home owners insurance is going to cover your butt?

Re:Perspective of an actual caver-geek (1)

jc79 (1683494) | more than 4 years ago | (#31009108)

Thanks, that's really interesting.

In Scotland, the legislation allowing for access to open land (which includes caves) specifically absolves the landowner of liability in the case of a person coming to harm by a natural hazard - otherwise every mountain and cliff would have to have warning signs along it.

I'm pretty sure the law in England and Wales has similar provisions, although access to land is not a right as it is in Scotland. It seems daft to make the landowner responsible for persons outwith their control.

Re:Perspective of an actual caver-geek (1)

RockDoctor (15477) | more than 4 years ago | (#30994330)

Very recently there have been people who went out for a day of caving and came back sans one member. See this story[http://cbs5.com/national/utah.cave.dealth.2.1337554.html]

Hmmm, interesting. Another "Neil Moss" event. "Film," as the jargon-file entry goes, "at eleven." There are a number of "Neil Moss" concrete lumps scattered through the caves of Britain and I would safely assume Europe too. That America has them too is no surprise. One of my fellow cave-diving trainees made the mistake of bringing some suspicious bones out of the cave once ... to be told by the local police : "Put them back where you found them, son. We know who they are, and the family don't need yet another batch of paperwork and another partial funeral." [Names and locations deliberately omitted. Well known in the sport.]

FYI, There's NO FN WAY you'd get me to cave dive.

Hmmm, typical stage 2 response :

  1. You're a newbie ; you don't know what cave diving is, and it doesn't arouse strong emotion.
  2. You're a reasonably experienced caver ; you've seen the roof disappear into the sump ; you've done some free diving ; you've lain on your back in that crawl and noticed the grass stems stuck to the roof. "No effin way!", as you say.
  3. You're an experienced caver ; the darkness beckons ; you are afraid, very afraid.
  4. You settle the gag in your mouth and let the water close over your head. The fear is still there, but it's just one more thing to be managed along with air, buoyancy, temperature, survey and line, ...

Being a little more precise, I think that you're hearing the darkness beckon, and you're about to go from stage 2 to stage 3. Or you're trying to square your public claims of "hardness" with your fear of the darkness. Don't worry ; fear is rational ; no-one who matters will think the less of you for declining the opportunity (apart possibly from yourself). What people won't thank you for would be not getting proper training if you decide to start to bubble, as you sound enough a member of the caving fraternity to get the contacts you need.
If I see you down a cave somewhere, enjoy.

That reminds me - I've got to get rid of my bottles. (Out of test and very old, so not worth shipping.)

Re:Perspective of an actual caver-geek (1)

Like2Byte (542992) | more than 4 years ago | (#31021664)

Being a little more precise, I think that you're hearing the darkness beckon, and you're about to go from stage 2 to stage 3. Or you're trying to square your public claims of "hardness" with your fear of the darkness. Don't worry ; fear is rational ; no-one who matters will think the less of you for declining the opportunity (apart possibly from yourself). What people won't thank you for would be not getting proper training if you decide to start to bubble, as you sound enough a member of the caving fraternity to get the contacts you need.

LOL. That's funny and brings up an interesting point about my ancient history - I almost drowned when I was ~2 years old by running into the ocean at Black Sands Beach in Hawaii. I still to this day remember the entire event in black and white memory. I remember every bubble swirling around my eyes and the swishing of the water in my ears. Apparently, I told my mother I'd stay out of the water. I lied. I went straight for it!! Almost drowned because of it.

My brother says I'm afraid of water. Actually, I'd rather swim under it holding my breath where I feel in control. I am fearful of the surface as I could sink at any time. Odd, isn't it. Maybe you are correct and subconsciously I am craving the training. Truth be told, I would like to learn to SCUBA.

It's just the video I've seen of cave divers pushing their tanks through a squeeze makes me shiver.

If I see you down a cave somewhere, enjoy.

Indeed!

Re:Perspective of an actual caver-geek (1)

RockDoctor (15477) | more than 4 years ago | (#31030640)

It's just the video I've seen of cave divers pushing their tanks through a squeeze makes me shiver.

You don't do it on every dive. Not even every second dive, unless you're particularly masochistic [GRIN].
But analyse : why do you find such scenes particularly disturbing? If you were doing the same manoeuvres with the same bottles (OK, yes they do add up to a small bomb ; but you've carried and set charges before, haven't you?) in the air, would that freak you? Of course not (that, by the way, is the reason that the British way of cave diving is to take cavers and teach them to dive, not to take divers and teach them to cave ; the cavers are less likely to freak over the diving than the divers are over the caving).
So, is the water what freaks you? but you're not going to get away from your bottles, are you? You're going to keep a *very* firm grip on them - a "death grip", you could say.
You are not going to over-stress yourself, because you know what that's going to do to your air consumption. You are not going to let your fears of the darkness and the water and the million tons of rock between you and air ruin your dive.
If the time and air consumption is going wrong for the dive, you are going to turn round when you get to thirds.
You are not going to be upset over one of your gags blocking - you've done a changeover between air systems in the last 5 minutes, haven't you? So you know that one system was working a breath ago, and the other system 5 minutes ago. That's why you do changeovers.
How on earth are you going to get lost down there - you've kept a good firm grip on your lifeline (note - it's a lifeline, not a guideline ; the name reflects just how good a grip you keep on it). And besides, you've maintained a note of your survey as you've gone in on the dive, so even if the line has parted behind you, you've carried your notes with you.
What else could go wrong? Light failure? Well, come on, you're a caver - you got bored with re-building your lamp in total darkness years ago. Which is why you're diving on triple or quintuple lamps (I met some Ukrainian divers once down Ireby Fell Main Drain - interesting kit, a torch mounted to the inside of each forearm instead of using the UK traditional 3-up of head lamps).
Two independent air systems ; three (or more) independent lighting systems. Multiple independent navigation systems. There's only one "single point of failure", and that's inside your head.
Which is why it's an interesting sport.

If I've convinced you to try it, don't.

I nearly drowned as a kid too. Didn't learn to swim until I was about 12. Before I started caving I'd had enough of the "OhShitOhShitOhShitThisTimeI'mReallyGonnaDie" moments rock climbing and ice climbing and suffering hypothermia and hitch-hiking the length of the country at 14 and getting lost in strange cities and I'd killed a guy through my own incompetence and getting arrested for political activities. The inside of my own head held no terrors for me.

Re:Perspective of an actual caver-geek (1)

Like2Byte (542992) | more than 4 years ago | (#31035042)

Interesting perspectives. Thank you for that.

Big Deal. (0)

Anonymous Coward | more than 4 years ago | (#30975140)

It sounds like he is using packet on HF. It is unfortunate that the article mentioned HF as being used for FM broadcast (that would be VHF). Amateur radio operators have been doing stuff like for a very long time. Big deal.

Morse Code (1)

greenlead (841089) | more than 4 years ago | (#30975174)

Carrier Wave (Morse code) would be way more useful than packet for rescue work. The only issue is that the splunkers would need to learn it. CW is a simple on/off sequence. It travels far, and is understandable even with a noisy signal.

Re:Morse Code (1)

ndege (12658) | more than 4 years ago | (#30977926)

Carrier Wave (Morse code) would be way more useful than packet for rescue work. The only issue is that the splunkers would need to learn it. CW is a simple on/off sequence. It travels far, and is understandable even with a noisy signal.

You might consider reading a bit about PSK31 packet [wikipedia.org] as it is much lower bandwidth than CW. The clear advantage of CW is that you can use a "transmitter" that doesn't require electronics. ie: a rock banging against another rock.

I posted a comment with more detail on PSK31 earlier see here: http://tech.slashdot.org/comments.pl?sid=1531648&cid=30977832 [slashdot.org]

a higher bandwidth lower tech approach (1)

belmolis (702863) | more than 4 years ago | (#30975890)

It looks like there's a need for an approach along the lines of RFC 2549 [faqs.org] , but using chiropteran [wikipedia.org] rather than avian carriers. Assuming that they can be trained, the bandwidth will be higher and the weight and volume to be carried by both cavers and rescuers considerably less.

Just run a damn cable ... (3, Insightful)

BitZtream (692029) | more than 4 years ago | (#30975960)

Seriously.

If you're leaving a sensor in a cave or mine to gather data, its going to be there a while. Take a spool of wire with you on the way in and just hard wire the thing for data and power.

Wireless is rarely the right way to do things, especially stationary things.

Re:Just run a damn cable ... (1)

fotbr (855184) | more than 4 years ago | (#30976764)

As long as the cable survives a mine fire, or a mine collapse, then running a cable is fine. If you can't guarantee the cable's survival, then wireless is probably the way to go.

Nothing new here (1)

DerekLyons (302214) | more than 4 years ago | (#30976096)

Alexander didn't "invent" anything. It's been known for decades that VLF waves will penetrate where other, higher, frequencies won't.
 
But VLF doesn't get used much in the real world because of it's low bandwidth, high power requirements, and the size and fragility of the antennas required.

Re:Nothing new here (1)

iamhassi (659463) | more than 4 years ago | (#30976738)

That's what I was thinking. They've been doing wireless communication for almost as long as submarines has existed. I'm sure 1940's sciencists are rolling in their graves right now.

The problem I heard with underground is that VLF required a very long cable. From what I heard submarines would let out a cable hundreds, sometimes thousands of yards long to commuicate. Maybe just 1,000 ft underground wouldn't need hundreds of yards but I'm sure it still needs a few dozen, far too much to carry down with you in a cave. His invention might work but it's not a practical solution which is why no one has bothered to "invent" this before

Re:Nothing new here (1)

fluffy99 (870997) | more than 4 years ago | (#30978098)

The receiving antennas are not nearly that big for subs (maybe you're confusing them with the towed acoustic arrays?). In fact the receiving antenna for surface ships is generally under 10-meters in diameter. Its the transmitting antenna that has to be enormous.

It appears this is basically using VLF using very directional antenna both in the mine and topside. Hence the reason for a large antenna that has to be assembled. This is also the major downfall as you need to accurately aim and locate both antenna.

Ground Communications (0)

Anonymous Coward | more than 4 years ago | (#30976770)

Never mind that Hams used PSK31 (eg Digital coms) and Audio frequencies to communicate 30 km via Ground Currents some ten years ago...

This is pretty routine stuff...

Mole phone? (0)

Anonymous Coward | more than 4 years ago | (#30976884)

Don't we already have a system that does exactly this called mole phone, sending text on VLF from deep underground is nothing new.

Great Tech, shame the antenna's so big (1)

physburn (1095481) | more than 4 years ago | (#30977120)

Each of end of the antenna is a 6 foot wides, geodesics sphere. The caver has to put it together to be able to comminucate with the surface. I guess its not that easy sending signals though solid rock, without a big antenna. Maybe they could make it smaller with a neutrino beam?

---

Ham Radio [feeddistiller.com] Feed @ Feed Distiller [feeddistiller.com]

Re:Great Tech, shame the antenna's so big (0)

Anonymous Coward | more than 4 years ago | (#30978480)

Good luck miniaturizing your fusion machine to make a neutrino generator!

Re:Great Tech, shame the antenna's so big (1)

braindrainbahrain (874202) | more than 4 years ago | (#30980672)

Methinks that antenna looks like the fabled Octoloop [www.vlf.it] (look about 3/4 down the page). Granted, it provides some useful antenna gain, but another disadvantage (in addition to its' large size), is that it has a very narrow beamwidth. This would restrict reception on the surface to a very specific location which would be hard to determine in a rescue situation if the rescueres don't know where the transmitter is located.

None-the-less, there is probably some niche applications for this (fault monitoring?) and I wish the inventor student the best of luck.

Re:Great Tech, shame the antenna's so big (1)

braindrainbahrain (874202) | more than 4 years ago | (#30982334)

Let me correct myself. The Octoloop has a very narrow _null_ (not beamwidth). In a recue situation, the rescuers on the surface could use the antenna's null to direction-find the transmitter.

DIY Texting System For Really Underground Radio (1)

viralMeme (1461143) | more than 4 years ago | (#30979580)

> There's some kvetching in the NPR story's comments that it's not the first use of cave radios, but that seems to miss the point ..

It is a valid point - not the first ues. It does demonstrate skill for a sixteen-year-old to be ables to design and construpt the device. An amalgam of VLF radio and a digital device. Communication underground has always been a problem. Leaky lines [ieee.org] are one such solution, either active or passive.

Saw this kid at ISEF '09 (0)

Anonymous Coward | more than 4 years ago | (#31001524)

It's really cool that a news article finally came out about this kid. Some crazy science went into making this. Very cool.

darryl (0)

Anonymous Coward | more than 4 years ago | (#31006438)

this technology has been around and in common use, well for just about as long as radio has been around, LF communications for miners is allready in common use. So nothing new here.

The trouble is with very low frequiency communications is at low frequencies the wavelength is very long, therefore you have to have very large antennas that are very low in efficiency.

When in the military, I used to maintain a 250Kw LF transmitter, (around 44Khz) for submarine communications, the antenna was housed (mounted) on 3 x 800 foot towers, and that was only for the capactive 'top hat' for increased radiation efficiency. But
to do low frequency comms, you need high power, large antennas, and low bandwidth. And low information rates.

So it's nothing new, it's been done and for a very long time.

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