> To put it another way, if there was a war so bad, the US reinstituted the draft, would these tools still be relevant?
The drafted people would all go to factories and boatyards to build thousands of new submarines. Each submarine would likely have no people on board, and be fully remote control.
The age old problem of "you can't hide while sending and receiving data, so you can't make a drone sub" has been solved by using below-noise-floor gold codes, so without the coding key, nobody can even tell a transmission is going on.
I'm a cryptographer, so I'm inherently curious about secret communication. It just so happens that I'm also very curious about radios, satellite communications, etc.
Do you have a link that provides more information on these "below-noise-floor gold codes"? I tried googling, but I haven't found much technical information that I trust is entirely truthful or relevant.
The principle is that if your ally has a receive antenna with a gain of X, and you use a modulation scheme with a coding gain of Y, and you transmit strong enough that your signal can be received by your ally with a snr margin of Z, then as long as your enemy doesn't have a receive antenna with gain > X+Y-Z, they can't detect your signal from the noise.
Since Y can be increased arbitaraly (at the cost of channel data capacity), it's always possible to transmit some information to your ally without your enemy seeing a transmission, it might just be a few bits per second, but theres a lot you can do with a few bits per second in warfare.
One needs to make sure that the above holds true for all possible frequency windows and time windows, so no carrier waves or high power sync pulses!
I believe the implementation is much harder than the theory - just one crystal oscillator or PLL anywhere in your radio hardware will leak some of that frequency into the output, and since the bandwidth of a crystal oscillator is super low (obviously an ideal oscillator has zero bandwidth), even a tiny leak is detectable by an enemy.
No doubt that's what the end of the war would look like. But war is, generally speaking, a kind of work on the field. That kind of work isn't currently done by robots.
I have read the comms channels underwater are low to very low bit rate. If true, a remote controlled sub seems unrealistic.
Also a remote control sub would be continually sending data back which surely is tantamount to continually yelling "I'm here! I'm here!", so I don't really buy the RC sub theory yet. (edit: I don't buy your suggestion that it's possible to hide that. You just need to emit too much power and you can't hide that).
Correct, you can’t remote control a submerged submarine, you get maybe a few characters per minute rate of transmission. There are a few ELF stations throughout the world, the US, Russia and India all having some.
Some more info: https://en.wikipedia.org/wiki/Extremely_low_frequency which has my favorite quote. “ ... few nations have built naval ELF transmitters to communicate with their submarines while submerged. China has recently constructed the world's largest ELF facility roughly the size of New York City in order to communicate with its submarine forces without having them to surface. ...”
The antenna needed for these transmissions requires a lot of land.
That's not true. I was working on a system to do (not on subs, but the techniques are applicable) that a few years ago. With a big enough array, anything is possible, see the entire field of radio-astronomy. This includes sparse arrays, as long as you have good enough time sync to do coherent integration.
The drafted people would all go to factories and boatyards to build thousands of new submarines. Each submarine would likely have no people on board, and be fully remote control.
The age old problem of "you can't hide while sending and receiving data, so you can't make a drone sub" has been solved by using below-noise-floor gold codes, so without the coding key, nobody can even tell a transmission is going on.