We're all doomed!
So if I want to jam this signal I would need a 12V battery, a relay, an car ignition coil and two nails for a spark gap.
As for navigation, when playing Doom I think the technique is to run down the tunnels killing everything that moves, then have a look around!
You'd need the mother of all car batteries to match the energy. Or perhaps one laptop battery going boom.
Will the energy from the magma surrounding my volcano based lair affect this?
Just asking, that's all.
Phase 1: Develop system for triangulating position based on lightning strikes. So soldiers wandering around in tunnels can find bad guys.
Phase 2: Develop super-villain system to generate lightning strikes at will anywhere on Earth. Ability to do this rather negating the need to send mere mortals down into tunnels.
Alternatively you could limit your wars to places with lots of lightning strikes, like the southern US, while avoiding desert countries which are not known for their rainy weather.
Phase 3: Profit
There's some more information and a cool online VLF radio at NASA:
I would have thought a highly accurate inertial navigation system (based on accelerometers and gyroscopes), perhaps coupled with some wearable "boot sensors" to more accurately track distance and a digital compass would provide much more accurate, dependable position fixes in 3 axes essentially via dead reckoning.
Certainly distance could be very easily tracked - unlike submarines, ships and aircraft using dead reckoning, the medium (water, air etc) isn't moving due to currents, so there's less drift to account for.
Perhaps a camera sensor that works like a giant optical mouse could track distance travelled like an electronic trundle wheel...
Ever seen sub gyros after a depth charge nearby?
The problem with this type of dead reconing systems is that the shock from even a small explosion like a grenade in a neighbouring tunnel can upset the sensors badly enough for them to become useless.
But but but...
There are plenty of supposedly highly-accurate 3D maps of extensive natural cave systems, including those caves that are underwater. So underground navigation has obviously already been sorted by the spelunking crowd. And the underwater detail means that they can't be spending endless hours fiddling with waterproof theodolites.
I think that Mr. Creswick has it nailed.
@ but but but
yes, there are highly accurate cave surveys but they take a LOT of work to produce and are usually made by measuring line of sight distance dip and direction between base stations, then running it through some cave survey software. Most caves in the UK are mapped pretty roughly, as long as the height of vertical pitches is accurate so rope requirements are known they don't need to be particularly detailed.
Would you like to volunteer to be first down an Iranian bunker armed with a compass and a measuring tape?
Thank God they invented the ...
Paris, crying, 'cause she knows all good things eventually "PUTTER OUT".
&...I'd add the Icon "of me taking my coat off", as I'm about to join her in the hot tub.
Cool. Now I'll know where all my lasers are. Shame that no one has come up with smaller 10kw laser units, the current fridge sized ones keep drowning my sharks.
Maybe you've mistaken lovable cetaceans or pinnipeds for evil squaliforms, and stuck your laser to a dolphin or seal, but the idea that sharks are so primitive that they drown if they stop swimming is mostly a myth (as seen from large numbers of sharks sleeping at seabottom, like nurse sharks and wobbegongs etc).
Hasn't this been solved already?
(Takes out well thumbed copy of "Greek Myths and Legends")
Yup, here we go. You nail a bit of string to the door as you go into the tunnel complex. You unwind the string as you go. Then, once you've destroyed the superweapon / nuclear reactor / mutant jihadi monkey army / enormous bull-headed monster*, you can find your way out again by following the string.
*Delete as appropriate.
Sharks don't drown underwater they have gills. Also sharks are very sensitive to electricity - they can sense the nerve impulses of other creatures in the water so attaching 10KW electrical items would fry them. Sorry you can't have frickin lasers.