you can’t turn a gas into liquid by compression alone if temperature is above critical point, you also need to cool it down. separation is done by fractional distillation, but the reason it’s done is mostly about oxygen (medical and steelmaking among some other uses). for nitrogen it’s somewhere about -150C. first air is stripped of water and carbon dioxide, then it’s turned into a liquid, then it’s separated into oxygen, nitrogen and argon, and some large specialized plants also separate xenon, krypton and neon

if you don’t actually care for it being a liquid, there’s another method called pressure swing adsorption that separates gases based on how tightly do they bind to porous surfaces under pressure. this is how medical oxygen concentrators work

making liquid nitrogen is pretty efficient these days, as in not much more energy is used than is actually needed

Yes. You would get tracked by your phone

this is just a really extravagant heater, physics forbids antenna this small to have good radiation resistance. for your contrived below noise communications scheme, you need more bandwidth that is physically possible on hf, yet you choose antenna design that is even less wideband than regular dipole. 40m of wire is for 80m band, which is usable more often in this configuration, ignoring everything else

As for throughput: a channel that is 9 KHz wide is supposed to transfer 9.6 kbit / s

5500kbps in extremely favourable conditions is your peak attainable speed, bandwiths in normal radios are narrower

A reasonable detection avoidance technique might be broadcasting from a depressed location or an urban canyon with tall ground clutter

if you don’t want anyone to hear you

launch your guerilla transmitter on a free flight balloon, and will have plentiful line of sight.

with what power source? better study for and get your license, start using radio and stop embarrassing yourself

you super stealthy nvis signal might not be noticed by anyone, including intended recipient, but your antenna farm made form 40m long wires certainly will

yes i know how spread spectrum schemes work, but this is not really practical or relevant here

for spread spectrum things to work you need some wide bandwidth, this works great for microwaves where you can spread your 90GHz band signal so that it covers 5GHz, you can’t have a signal centered on 5MHz that is 5GHz wide; HF is relevant because while microwaves work with this microwaves are line of sight only and most people’s line of sight still terminates in their own country. if you live on a lone hill next to border good for you, but the rest would need to use HF to get out, and there’s simply not that much bandwidth available in the first place, which would make any scheme like this extremely slow if at all viable. and you can still jam it

i don’t assume that satellite repeaters would be a viable option because satellite, or any other receiving party for that matter, would need to be aware of modulation scheme to receive it in the first place, so it only works if your international contacts are pre-arranged, and even then you need radio that has much larger bandwidth that is usually available. yapping on LSB or narrow digimodes will get you heard within continental range, but also it will get you noticed, but if you hide from your adversary you also hide from everyone else not in the know. and even then, you can still get noticed, because it’s under noise level only at some distance from you

also some of these schemes require precise time to be known, and if you have gps jammed you’ll get extra problems from that

ranked competitive version is called foxhunting and even kid can do it

you’re also a shining beacon every second you transmit and even states with moderate capabilities record their radio spectrum 24/7 even during peacetime

agree on uncensorable but keep in mind ham radio is antiprivate by design - every time you say your callsign you sign off

substack is not news

trump rn

shooting down bosses stupid ideas is #1 productivity tip for professionals (like most people on lemmy are)

that town is just a bit north to border with chechenya, going in straight line from there to teheran overflies only russian, azeri and iranian airspace. the only nato member nearby is turkey, and you have to go out of the way to hit it. azeri-iranian relations are suboptimal, but even then they can go over caspian if they want to avoid it

map would explain it much better

roughly tube with a very thick wall and spherical ending (it has to survive 100+ atm under high temperature and neutron irradiation - weakens everything over time)

as i understand, this is what bellingcat uses as a major source of data when reporting on russian activities

“It is one of the paradoxes of modern Russia: on the one hand, these services are illegal and rely on leaked data, yet on the other, they are far more convenient for day-to-day police work than the multitude of official departmental databases,”

gaben on piracy: “We think there is a fundamental misconception about piracy. Piracy is almost always a service problem and not a pricing problem,”

There is a thermal energy storage included as s major part. This works because compressing CO2 to 55atm adiabatically heats it up to some 450-ish C, so that heat is pretty high grade, and only the final stage cools it down with heat exchanger open to air. In discharging direction, some heat is taken from outside air to evaporate part of CO2 and heat stored is used up

compressors, turbines (like steam turbines), piping, some of which heat-resistant (500C), container for liquid carbon dioxide, lots of plastic for the bubble, something for thermal storage, dry and clean carbon dioxide, these aren’t unusual or restricted resources, don’t depend on critical raw materials or anything like that

Compressed air without heat recovery is more like 30%, so this is huge

Carbon dioxide can be liquefied relatively easily which is what i guess makes this efficient

wood, magnesium, aluminum, plastics, they say titanium is bad, but i’d expect iron, nickel, manganese, tungsten, silver, maybe zinc to be worse

no no no no it’s on by default so it’s opt-out, and switch for that isn’t even implemented yet

in this economy?