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DIY Texting System For Really Underground Radio
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.
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.
Running with Linux for over 20 years!
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.
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.
Please help metamoderate.
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
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
Wikipedia Entry: http://en.wikipedia.org/wiki/Cave_rescue
Fourth. If you want to know more about caving visit Emily's website: http://www.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/
FYI, There's NO FN WAY you'd get me to cave dive.