Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Tracing a powerful GNSS interference source over Europe

arxiv.org

Post reply on HN
Print view View original

231–240 of 256 posts

Re: Tracing a powerful GNSS interference source over Europe

#231

Post by colechristensen »

Aerroon wrote: post #223
colechristensen wrote: post #189

Earlier quoted context omitted.

A missile intercept for explosions or a kinetic destruction the relative velocity will be measured in kilometers per second. A little nudge doesn't do much, it's still a satellite in a substantially similar orbit. Any sort of nudge requires intercept, go up there and match its velocity so you can grab it and push. And still you have to push on it a whole lot to make a meaningful difference. Spin it up? You'd have to…

An apple at highway speeds can break the windshield and make the car undriveable. People throwing things from highway overpasses is a serious (and deadly) problem. > A missile intercept for explosions or a kinetic destruction the relative velocity will be measured in kilometers per second. The satellite will also be going kilometers per second. You have to almost match the orbital velocity to have a chance of hitting…

To the contrary, for the 1 satellite missile strike we have public information on, not only did it not catch up to the orbital velocity for intercept, it hit it head on (going the other direction) adding to the relative velocity. A satellite with an ~8 km/s orbital velocity was struck head on by a missile adding to that by ~2 km/s for a total just under 10 km/s.

It is indeed not that hard to intercept something in orbit. Because the orbits don't change and can be predicted to high precision months in the future.

Re: Tracing a powerful GNSS interference source over Europe

#232

Post by colechristensen »

nutjob2 wrote: post #13
colechristensen wrote: post #10

Earlier quoted context omitted.

>I wonder if we can do something now that we know the source. Russia signed the 1967 Outer Space Treaty (OST) in 1967, this may be a treaty violation of this or other treaties, something like that or retaliation regarding it may be possible. You can hack the satellite, or use other electronic warfare options to jam or interfere with it's operations. You can shoot it down with a missile. The X-37B is in space right no…

> You can shoot it down with a missile. Obviously a bad idea, but frying it with some sort of high powered electromagnetic pulse would seem the smartest option with plausible deniability. I wonder if the US already has such weapons in orbit.

X37-B it's a tiny robot space shuttle launched by the military.

Why WOUDLN'T one of its possible payloads be an electronic warfare package? Go up to an adversarial satellite, do some signals intelligence capturing things, have a jamming package, or a stronger EM output to fry circuits.

Re: Tracing a powerful GNSS interference source over Europe

#234

Post by b65e8bee43c2ed0 »

justsomehnguy wrote: post #220
b65e8bee43c2ed0 wrote: post #175

Earlier quoted context omitted.

okay, let me rephrase that: would it have taken two wars to subdue that tiny, sparsely populated country had that country been armed with nothing but sticks, stones, and Molotov's?

Ah, yes the famous sticks with "AK-74" and "RPG" on them. It's also amusing how the stupid Soviets took two wars to subdue that tiny, sparsely populated country had that country been armed with nothing but sticks, stones, and Molotov's; while the mighty, eagle screeching top-tech first world economy with a giant student debt took checks notes two decades to accomplish check the notes again replacing Taliban with Tali…

you appear to have misread my comment. I didn't say the Chechens were unarmed.

Re: Tracing a powerful GNSS interference source over Europe

#235

Post by rcxdude »

ralferoo wrote: post #226
rcxdude wrote: post #195

Earlier quoted context omitted.

You do generally need a tuned filter before the rectification, unless you have an extremely large signal dominating the local airwaves. Which is precisely the parent poster's point: with RF you are almost always doing something to demodulate the signal. Whether you are doing it with a sine wave or something more complicated is not that fundamentally different. (and if you're looking at a spectrum analysis, that is lo…

I'd argue that "correlation" is an accurate description of what you're doing with Gold codes - you're testing the known sequence of the output of a PRNG against the received signal, and only accepting it when the data correlates, otherwise you're adjusting the offset and trying again until you find a high correlation (strong +ve and -ve spikes) or you give up and assume there's no transmission. There's nothing in the…

A strong signal 'that's obviously there' is only obviously there after you've already filtered it to some extent. If you were to look at the raw broadband RF environment on a scope you very much would not see the vast majority of signals there. And when you're demodulating you do often need to tune the phase and frequency of the carrier you're demodulating with, as well. GNSS signals are just generally quite low bandwidth and so that process takes a while.

Not to say that such codes aren't a neat trick, but it's useful to consider that these are in many ways the same thing.

Re: Tracing a powerful GNSS interference source over Europe

#236

Post by UltraSane »

notagorn wrote: post #187
badc0ffee wrote: post #174

Earlier quoted context omitted.

The (misguided IMO) idea was that buying their gas and integrating them into world markets would strengthen ties and liberalize them in the medium term. Nobody believes that anymore, post-2022.

I don't think it was misguided; Nuland-Pyatt leak and the tapping of Merkel's phone made it pretty clear to me that like in the Yeltsin years the problem was that the US didn't want Russia/Europe ties to succeed.

Russia didn't want Russia Europe ties to succeed. That is why it invaded Ukraine.

Re: Tracing a powerful GNSS interference source over Europe

#237

Post by UltraSane »

justsomehnguy wrote: post #172
lenerdenator wrote: post #149

Earlier quoted context omitted.

And? When the Russians invaded Georgia in 2008, Europeans inked a deal for a second gas pipeline with them, Nordstream 2. When they annexed Crimea in 2014, Europeans went to the Sochi Olympics (which happened that same year ) and went to the World Cup in 2018. And this is before you take into account the dozens of smaller incidents. Those aren't "threats to invade European territory", not even ones that were ignored…

Remind us, why US Congress funds a country on literally the other side of the planet?

Because the world is actually very small and Ukraine winning helps the US

Re: Tracing a powerful GNSS interference source over Europe

#238

Post by ralferoo »

rcxdude wrote: post #235
ralferoo wrote: post #226

Earlier quoted context omitted.

I'd argue that "correlation" is an accurate description of what you're doing with Gold codes - you're testing the known sequence of the output of a PRNG against the received signal, and only accepting it when the data correlates, otherwise you're adjusting the offset and trying again until you find a high correlation (strong +ve and -ve spikes) or you give up and assume there's no transmission. There's nothing in the…

A strong signal 'that's obviously there' is only obviously there after you've already filtered it to some extent. If you were to look at the raw broadband RF environment on a scope you very much would not see the vast majority of signals there. And when you're demodulating you do often need to tune the phase and frequency of the carrier you're demodulating with, as well. GNSS signals are just generally quite low band…

By "obviously there", I meant take some old analogue receiver and twiddle the tuning knob. The vast majority of radio transmissions are many orders of magnitude louder than the noise floor. They are very obviously there.

Tune your SDR radio down to 1.023MHz, you'll see nothing there at all. The signal is about 20dB below the noise floor. The only way you can pick out anything at all is by correlating it against the PRNG with the correct offset in the sequence.

The GP post (to be fair, I should have replied to the post 2 higher up) was arguing that all signals are weaker than the noise floor and demodulating using a carrier was exactly the same thing. It is in one way, but also not in another - in that you need to keep trying different offsets in the PRNG sequence until you find a correlation. That's why I think "correlation" is a sensible term for Gold Codes, but "demodulation" is better for signals modulated by a sine wave carrier.

Re: Tracing a powerful GNSS interference source over Europe

#239

Post by danicriss »

yehat wrote: post #98
Havoc wrote: post #34

Earlier quoted context omitted.

>must surely be impacting the Russian residents as well, right? They don't give a fuck. Was watching a youtube video by a russian the other day talking about war & sanction impact and things like ride sharing apps literally say on screen the location is going to be wrong and to select pickup spot manually. It's just assumed to be fucked as a given even at an app development level

Does ukrainians and romanians give a fuck, 'cause not many russians live in the north-west part of Black Sea? And the jamming there's from who?

Afaik the grains corridors for the Ukrainian ships are alongside the Romanian coast, hence the Russian interest

> Do Romanians give a fuck?

A Ukrainian USV (water surface drone) just exploded the other day in Romania's main industrial port (Europe's 4th largest for a sense of scale), apparently thinking it's somewhere else due to GPS EW interference. Yes they're affected, yes they care

Re: Tracing a powerful GNSS interference source over Europe

#240

Post by trumpdong »

ralferoo wrote: post #238
rcxdude wrote: post #235

Earlier quoted context omitted.

A strong signal 'that's obviously there' is only obviously there after you've already filtered it to some extent. If you were to look at the raw broadband RF environment on a scope you very much would not see the vast majority of signals there. And when you're demodulating you do often need to tune the phase and frequency of the carrier you're demodulating with, as well. GNSS signals are just generally quite low band…

By "obviously there", I meant take some old analogue receiver and twiddle the tuning knob. The vast majority of radio transmissions are many orders of magnitude louder than the noise floor. They are very obviously there. Tune your SDR radio down to 1.023MHz, you'll see nothing there at all. The signal is about 20dB below the noise floor. The only way you can pick out anything at all is by correlating it against the P…

What you're describing is correlating the received signal with complex sine wavelets of various frequencies.
Post reply on HN