Show HN: Formally verified FPGA watchdog for AM broadcast in unmanned tunnels

At first I thought the "unmanned tunnels" description was just a way to avoid broadcast regulator scrutiny, but it does look like it's genuinely designed to be used underground as part of an emergency alert system. That led me to "leaky feeders", a type of broadcast antenna used in mines and tunnels.

https://en.wikipedia.org/wiki/Leaky_feeder

Could obtain better quality at the higher channel counts by phase shifting the audio for each channel such that the modulation peaks do not exactly align for each (as they do now). Even inverting the audio for half the channels would help.

I happened to find a video about how the Osireon in Egypt is similar to structures constructed within Longyou caves. They are historically contemporary and they are separated by a multiple of 72 degrees. Angkor Wat and (TODO a number of other ancient facilities) perhaps coincidentally are also on a geographic pentagon at 72° degrees.

Unfortunately, due to TODO some sort of procession you would expect such a LF/VLF comm net to be off by about 1° after 72 years though? Perhaps this is part of why they built new temples etc. adjacent to older sites. The Temple of Seti is built adjacent to the Osireon, for example.

Anyways, the scalloped marks on the walls of Longyou caves very likely operate as LF/VLF diffusers for local and far away signals that propagate TTE Through-the-Earth and also through water and hydrogen.

At 21cm, the northern Star Shaft in the Great Pyramid waveguides 1420 MHz. 1420 MHz is the fundamental frequency of Hydrogen.

The star shaft contain 0.25" copper rods that would have been deoxidized by hydrogen. The star shafts were enclosed. People have speculated that they were for ventilation, but the star shafts were found sealed with the oxidized copper rods inside.

That copper could have been from the Great Lakes back then.

Why would you add copper rods to the tallest structure around in the desert, in shafts that would accumulate hydrogen if the structure was filled with water that foams as it drains out?

Are those antennae and/or ionospheric and/or lightning charge collectors to charge the granite and discharge to make plasma in a 6,000 ton pressure vessel?

Is that an above ground cave? An above ground cave that makes: (0) ionized Water sanitized with hydrogen plasma and solar sanitized water, (1) Gold and Neodymium from SPP Surface Plasmon Polaritons in quartzite sand in electrified hydrogen plasma, (2) Doped A-CNT Carbon Nanotubes that glow blue in the presence of hydrogen and Diamond (3), and RF and EMF? Wouldn't it have been a beacon on multiple frequencies?

Anyways,

The pressure vessels found in Egypt - for example with a pyramid built around it at Saqqara - very likely resonate tuned LF resonance.

The pressure vessels may resonate a source signal that would stabilize hydrogen being slowly emitted to cool a quantum locked floating barge that could have made it easier to transport and place 100 ton granite blocks from a quarry miles away.

Also though, there are a number of hypotheses about pyramid construction that do not involve levitation or quantum locking of a depressurizing hydrogen vessel over neodymium - and maybe gold for corrosion - tracks or rails. Stephen Myers, for example, describes placing stones with barge cranes floating in a pool bounded by casing stones first. The Grand gallery (todo) does appear to be shaped like a water lock and there was no ladder or railing. And there are redundant portcullis doors. But the math to move a 100 ton stone without crushing wooden barges.

...

LoRA will work better than AM in a cave.

There are AM dead zones in caves. Scalloped walls that diffuse like Longyou caves can probably reduce those dead zones.

It looks like modern TTE systems are also built on VLF/LF.

Receiver cost for AM vs LoRa; but range? And then why not LF/VLF?