Very slow frequency modulation. Slow enough you could hear the tone change slightly as it shifted modulation every few seconds.

Frequency Shift Keying is the more accurate term for this, as it’s not a continuous shift up and down of the frequency like you’d get with FM radio, it’s stepped.

If you imagine a higher tone being decoded a “1” and a lower tone being a “0”, basically it was something like that. Listen long enough and you’d get enough 1s and 0s to build up a message.

That part’s easy, you just mine a tunnel, and then you mine a parallel tunnel 500m away from the first one. Ta-da , 500 metres of solid rock now exists between the two.

Note: mining a tunnel through solid rock can be somewhat difficult if you don’t have the right equipment, YMMV.

But seriously, the amount of dicking around maintaining the loop and the limited abilities of VLF meant that you would quite quickly have to run leaky feeder and bidirectional amps for two way radio, or you’d build a network using fiber and use Wi-Fi. We primarily used the system for remote blasting, and then once technology progressed a bit the initiators were connected via the network instead.

You could normally blame your GSM phone for that, it would be woken up by a cell tower to do a bit of high powered chatter before actually ringing or receiving a SMS.

“dude, where’d you get 500 meters of solid rock?”

The stuff’s everywhere, it’s actually pretty hard to get away from it haha.

Yeah that’s just the norm in Australia for nearly every year as almost the whole country experiences just two seasons - “wet” or “dry”.

P.S. sorry about giving you the idea to plant all those eucalypts over there during the gold rush, that was a bit of a mistake.

How are these any worse than the MAMILs?

Let’s see, they are:

• Generally faster and more unpredictable.

• Heavier, compared to MAMILs endless quest to have the lightest rig possible to get that PB time to work. So when they hit a pedestrian, they hit hard.

• Driven by kids without a fully formed concept of risk and consequence.

• Who are not wearing hi-vis lycra and safety gear.

So overall, I’d prefer middle aged men in lycra.

Yep, mining.

It ran throughout the mine and the mine layout was such that it was basically a vertical loop that was pinched in the middle with two lobes either side. Basically it ran up in the top corner of tunnels, and just hung vertically in ventilation shafts and boreholes when needed.

Gauge was about 6 or 8 mm2 edit: 10mm2 (8 AWG), from memory the overall loop resistance was about 20 ohms.

Plenty of splices due to damage from heavy equipment, and there were a few spots where we could break the loop and test which part was shorted or open.

You could use just standard electrical wire connections like BPs as it wasn’t particularly high voltage or current and there was no attempt to make it radiate “nicely”, plenty of spots where we used twin core cabling to extend the loop to some section and basically the opposing currents would cancel the field on that length of twin.

Used for underground messaging and blasting. If you search for " MST PED system" you might find some info, it’s pretty obsolete now that most places use Wi-Fi and vhf uhf radio on leaky feeder underground.

Don’t worry, general physics means that this is just another investment scam.

I’ll explain it out so you can get the general idea;

In order to reflect a sun’s worth of sunlight, you need a reflective surface in low earth orbit that is somewhat larger than the angular size of the sun from our perspective on the ground. Imagine just using an ordinary mirror at home, you need to see the whole of the sun in it, and that works out to be about a little mirror about the size of your thumb at arm’s length. In low earth orbit that mirror ends up being about 2km across.

To get that kind of reflective surface area in orbit you need about a couple of thousand 50 metre wide reflectors on satellites, just to reflect light to a single location with the rough equivalent of sunlight.

And then at the height of low earth orbit the earth eclipses the sun for quite a bit of time, so the sats that can see the sun during the night below on Earth are actually only able to do so for a couple of hours before sunrise or after sunset. So now you need to launch 10x more sats so that the sats that can see the sun can reflect light to where you want it.

So let’s just say 20,000 sats to start with.

With some clever engineering, you could probably make them the same size as SpaceX sats, and they launch about 25 at a time for a customer cost of about 70 million USD.

My calculator says that the launch cost for this is 56 billion USD. And then sats in that orbit with huge, high drag panels will get pulled into the Earth’s atmosphere after about 5 years, so you just need 56 billion up front plus about 10 billion a year to maintain the constellation, forever, and with all of that stuff flying around up there you can direct 1 suns worth of solar energy to 1 location.

Now you could take that array and split it up and provide, maybe a moonlight effect to a hundred places, and maybe, maybe, a hundred someones might pay the hundred million a year to feebly light their city streets or something. Seems a bit of an ask when there’s plenty of ways already to turn night into day locally for a lot cheaper.

BUT - you could also repurpose those 20,000 sats to provide a dozen sun’s worth of energy to any point on earth during the day when about half of them can easily see the sun.

This sure sounds like a practical equivalent of a death ray to me, which means all this bullshit will never get anywhere because no country in the world will allow anyone to build it.

So rest easy, this is just another way to scam venture capitalists and won’t go much further than these press releases.

I maintained a VLF through the earth transmitter for a while, it was a 15 km loop running at 470Hz and it could go about 500 metres through solid rock to a receiver about the size of a small lunchbox that had a ferrite coil tuned to match.

Loop ran at about 5 to 6 amps at 250 volts (~1200 watts) and was extended now and then, so there was a rack drawer full of matching circuitry to help get it to resonate nicely.

Used FSK at +/- a couple of Hz to very slowly encode text messages, used to take a minute to encode 16 characters, but there were a few “standard messages” for emergencies that could be sent in just a few seconds of coding.

The 470Hz tone got coupled into everything - you could hear it on phone lines, audio on network cameras, anything with a microphone and amp within a hundred meters of the loop would pick it up and you could hear the FSK shifting to a different tone every second or so.

The loop had quite a bit of capacitance. When there were loop faults you’d disconnect the amp and matching circuit and test the loop with a megger at 500 volts. It would take a few seconds to charge and stabilise the reading compared to near instant readings when meggering normal electrical circuits.

When there were no ground faults it would store that charge and give you quite the belt for some time afterwards if you didn’t drain it. So after the first couple of times you learned to short the loop after testing!

No no, the article clearly states that locals are INFURIATED, all of them. There’s no mild annoyance or irritation, it’s fury or nothing these days I’m afraid, that’s just how it is.

Flying toasters need to make a comeback I reckon.

Lithium ion batteries have a sweet spot of around 60 to 80 percent charge where very little wear takes place to charge or discharge. If you could keep it to just that 20-30 percent usage in that range it would pretty much last ten thousand cycles.

Charging to 100 or discharging below 50-60 percent accelerates the wear on the battery, but it is still much better than the wear rate on lead acid batteries that are cycled in a similar manner.

The picture you offer for comparison is literally a truck load of batteries though. Seeing that an EV’s battery typically fits under the floor pan of the car, are we talking like, the equivalent of 10 cars worth of batteries in that pic?

But once the interior of a car catches fire from whatever starting source the pictures all look pretty much the same as they’re all filled with lovely hydrocarbon-based plastics that all burn in the same manner.

Kyle and Jackie O’s controversial breakfast radio show taken off air after hosts fall out

And nothing of value was lost.

I’m sure we did a cycle of network booting thin clients and windows terminal services about 10 or 15 years ago. 🤔

There’s slack time in people’s daily work hours. You work an 8 hour day, possibly you’re only actually productive for 4 to 6 hours.

Take that into account and suddenly that thing that claims it can cut an hour or two here and there gets a lot more interesting.

Lamborghini? The tractor company? Of course it was always about the feel.

It’s just being heavily reinforced now that even the Volvo in my garage can quietly beat them to the next set of lights.

An electric/hybrid powertrain would have made them relevant again, and they could likely get by on style even if performance is a bit lacking.Sad that they’re not choosing to do that.

Pretty sure Lamborghini took one look at BYD’s three thousand horsepower supercar eating up the test track at 300 miles an hour and just quietly decided to pivot reinforce “the feel”.

Edit: “reinforce” is probably a better word than “pivot” , so I’ll use that, just so all those lambo apologists out there don’t have to post “iTS aLwAyS bEeN aBoUT tHe fEeL.”

“Human sacrifice, dogs and cats living together… MASS HYSTERIA!”

Oh come on now, that’s a defeatist attitude!

There’s always scope to further extract value for shareholders!