ELF.

This is coolbert:

With the advent of nuclear propulsion, the submarine became a true submersible that could remain submerged more or less indefinitely during a cruise.

Capable of high-speed underwater [in contrast to a World War Two [WW2] submarine] and indefinite submersion when required, the nuclear submarine was and is an excellent platform for carrying and delivering to a target atomic weapons if necessary.

The nuclear powered post-WW2 submarine was and continues to be stealthy, hidden, fast, and very dangerous.

But does have a drawback.

Communication with a submerged submarine is difficult, if not next to impossible.

Rising to the surface to receive radio messages defeated the whole purpose of having a submarine that could remain underwater, hidden, for months on end.

Communication via radio transmission was possible, but only with great difficulty.

One answer to the communication problem that seemed to NEVER come to fruition was the ELF concept. Extremely-low-frequency communication, in the low audio to sub-audio range.

In America, this was called Project Sanguine. ONLY existed in the development stage, and finally was abandoned.

ELF calls for a transmitter to have it's antenna to be placed in a geologically suitable location. Within the continental U.S. ONLY two such suitable locations exist. One in Wisconsin, the other in Texas.

Sanguine originally called for an antenna that would be THOUSANDS OF MILES LONG - - CIRCULAR, to be buried in the ground around Clam Lake, Wisconsin. Objections by locals resulted in much smaller size antenna being emplaced, primarily for experimental purposes.

Experimental, one-way broadcasts did occur for a period of decades. The entire project finally being scrapped in 2004. Results of the experimentation are known only to those that "have a need to know". OR, WERE INCONCLUSIVE!!

I know that from time to time, persons living around Clam Lake, actually for some distance away too, would report that their phones would begin to ring for no apparent reason. Apparently the transmissions were of such frequency and power that locals - - began to receive phone calls - - from nobody!!??

Even the U.S. Navy, finally, decided that Sanguine was no longer worth the effort and gave up.

National defense does have it's limits!!

coolbert.