Hacker News Reader

Comment by URSpider94 | Hacker News Reader

This is different but related. China has no ability to influence GPS accuracy within its borders. What they do is manipulate all of the authoritative maps available so that GPS coordinates won’t map cleanly to the digital waypoints in the map. The GPS locations are very precise, they are just off by as much as a quarter mile in varying directions depending on where in the county you are.

View on HN

Can OpenStreetMap or someone make non-authoritative maps, or is this impossible without the cooperation of people on the ground who cannot operate safely within the borders of China?

At one point we spent some time reverse engineering the Chinese coordinate system, it’s actually quite fascinating. So terrible though.

But OSM actually doesn’t use that system! They use the normal coordinate system, which makes them unique across mapping services (and also a good tool to use to RE geojson away from chinas system).

It's "impossible".

Private, independent geographical surveying is illegal in China. [0] So technically you can't do it even in the local coordinate system.

[0] https://en.wikipedia.org/wiki/Restrictions_on_geographic_dat...

But I guess to OPs point, you could make a non-authoritative map based on satellite imagery, it just wouldn’t be legal to use in China.

OSM has an extensive article about mapping in China. Generally it's not allowed. Still, in the bigger OSM is quite accurate. :>

Anything that can be seen from a satellite is quite accurate, that's true, but oftentimes things like number of lanes, type or direction of the roads is unknown, footpaths in rural areas are very spotty. Basically anything that requires local human verification (addresses, business location, etc) is off limits and accuracy in those points comes from pre-ban times (or illegal activity).

> This is different but related. China has no ability to influence GPS accuracy within its borders.

FYI: And even far outside of them too

I don't think so Tim.

https://spacenews.com/pentagon-report-china-amassing-arsenal...

The current ASAT weapons can only hit targets in low earth orbit, and the GPS sats are way above that. Anything that high up that is military run also likely has capability to maneuver to avoid something shot from the surface (which will take a lot of time to get up that high even if it has enough energy).

"China already has operational ground-based missiles that can hit satellites in low-Earth orbit and “probably intends to pursue additional ASAT weapons capable of destroying satellites up to geosynchronous Earth orbit,” says the Defense Department’s annual report to Congress on China’s military capabilities."

The problem with defending a satellite is the missile really only needs to get kinda close. And yeah, relativistic speeds and distances in space are huge, but I would find it hard to believe we could defend our satellites in any meaningful way against a nation-state level threat.

At this point, destroying the positioning network/s would be mutually assured destruction. Pretty much every country relies on those networks equally for controlling their own vehicles and weaponry.

Some of those systems do. Not all.

" It is an Inertial Guidance System with an additional Star-Sighting system (this combination is known as astro-inertial guidance), which is used to correct small position and velocity errors that result from launch condition uncertainties due to errors in the submarine navigation system and errors that may have accumulated in the guidance system during the flight due to imperfect instrument calibration. GPS has been used on some test flights but is assumed not to be available for a real mission. "

https://en.wikipedia.org/wiki/Trident_(missile)

Tomahawk missiles are also fed a navigation package before launch which allows them to navigate without additional signals (I'm sure accuracy goes up if they do have GPS available). I believe it's something akin to terrain maps that it can use to navigate to it's target.

I would argue that any nation that is reliant on those public networks to be effective are going to lose within minutes of an actual conflict.

I believe it's already established that the Russians are capable of completely blocking out GPS signals.

https://www.nbcnews.com/news/vladimir-putin/russia-spoofing-...

So no, I don't think we'd be facing mutually assured destruction.

Now the impact on civilian life if some nation decided to start the space wars? Catastrophic. We'd basically block off space for the next 100 years because of deadly debris in orbit :/

And the debris created from a kinetic weapon would indiscriminately destroy other satellites at those altitudes. See https://en.wikipedia.org/wiki/Kessler_syndrome

Reply on news.ycombinator.com