The rock phone probably uses the ELF bandwidth used by the US Navy for the past 50 years. I'm sure the technology is classified or proprietary or both. With a tuned antenna, enough power, and the right geology these transmitters are global.
_____ From: Brian Vauter [mailto:bvau...@gmail.com] Sent: Friday, July 02, 2010 4:02 PM To: texascavers Subject: Re: [Texascavers] Re: Ultra Electronics "Rockphone" I had also noticed their lack of any real data on the phone's range through rock. There's a link to a publication called the Government Security News that has an article on the Rock Phones. In the article, they also don't mention how far the voice signals can penetrate. An interesting aside, however, is that they also state that US Special Forces paid them $5.7 million for a special detonating device (MI-RAMS) which can transmit a signal through 150 to 500 meters "of any material (soil, rock, etc.) to remotely detonate explosives. A vehicle-mounted system can apparently transmit up to 1,500 meters. I assume that the signal to make "boom" is easier to send than the signal to say "boom." Here's the link to the article: http://www.gsnmagazine.com/article/20744/ <http://www.gsnmagazine.com/article/20744/%E2%80%98rock_phones%E2%80%99_coul d_help_us_forces_pursue_osama_bi> 'rock_phones'_could_help_us_forces_pursue_osama_bi -brian On Fri, Jul 2, 2010 at 2:51 PM, Mark Minton <mmin...@caver.net> wrote: It seems rather suspicious that they do not give a useful operating range for this Rock Phone, even in the pdf of additional information (which in fact has no specifications). I wonder how much rock it can penetrate. Mark Minton
