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

Calculating position from raw GPS data (2017)

telesens.co

Post reply on HN
Print view View original

11–20 of 58 posts

Re: Calculating position from raw GPS data (2017)

#11

Post by patze »

namibj wrote: post #8

Android provides carrier phase access for a while now, and with that relative positioning between such devices in about the same neighborhood can be done with enough precision that you have to care about where in the device the GNSS antenna lurks. That alone isn't too fancy; it gets good once you throw in the accelerometer and gyroscope in each device. Because with that you get this not only in realtime, but also wit…

Sounds interesting! Does this approach work in indoor scenarios? Would you mind to provide some further links/papers to this topic?

Re: Calculating position from raw GPS data (2017)

#12

Post by cmsj »

AlexanderTheGr8 wrote: post #10
Jerrrrrrry wrote: post #6

Earlier quoted context omitted.

Just remember to intentionally handicap yourself as to not infringe upon ITAR restrictions.

Can you explain what you mean by that? The only thing I can think of is that GPS has 2 modes : one civilian and other military use. But military use-case uses encryption so civilians can't use that mode anyway.

GPS was built primarily for the military and the signals available for civilian use were crippled to reduce accuracy. GPS receivers that provided high accuracy fell under the ITAR rules (ie you needed proper licensing to trade them)

Over time such restrictions have largely been lifted, but there are still US export controls on GPS receivers with particular features, such as those designed for use in high speed aircraft, those able to decode the still-military-only encrypted signals that piggyback GPS and provide greater positioning precision, or those designed for use in rockets/UAVs.

So, it's reasonable to assume that if you were to build your own, and do too good of a job, you would accidentally become subject to arms trade regulations, and that's probably not a place you want to unintentionally find yourself, particularly if you're publishing it as open source on the Internet :)

Re: Calculating position from raw GPS data (2017)

#13

Post by Thaxll »

Jerrrrrrry wrote: post #6
cmsj wrote: post #3

For anyone wanting to build their own GPS receiver, here's a fully open source project that explains a great deal of the theory too: http://www.aholme.co.uk/GPS/Main.htm

Just remember to intentionally handicap yourself as to not infringe upon ITAR restrictions.

"The vast majority of civil and commercial GPS/GNSS equipment does not meet the Cat XII(d) criteria and is therefore not subject to ITAR"

https://www.space.commerce.gov/itar-controls-on-gps-gnss-rec....

Re: Calculating position from raw GPS data (2017)

#14

Post by nobodyknowin »

AlexanderTheGr8 wrote: post #10
Jerrrrrrry wrote: post #6

Earlier quoted context omitted.

Just remember to intentionally handicap yourself as to not infringe upon ITAR restrictions.

Can you explain what you mean by that? The only thing I can think of is that GPS has 2 modes : one civilian and other military use. But military use-case uses encryption so civilians can't use that mode anyway.

Not GP but modern GPS / GNSS manufacturers intentionally do not allow their devices to function over some speed (1000 mph or something like that).

So they won't work on warheads as part of a guidance system.

Re: Calculating position from raw GPS data (2017)

#15

Post by AlexanderTheGr8 »

nobodyknowin wrote: post #14
AlexanderTheGr8 wrote: post #10

Earlier quoted context omitted.

Can you explain what you mean by that? The only thing I can think of is that GPS has 2 modes : one civilian and other military use. But military use-case uses encryption so civilians can't use that mode anyway.

Not GP but modern GPS / GNSS manufacturers intentionally do not allow their devices to function over some speed (1000 mph or something like that). So they won't work on warheads as part of a guidance system.

I never really thought of that. That's a pretty interesting restriction. Although any party with access to warheads that can fly 1000+ mph probably can bypass the GPS restriction, no?

Re: Calculating position from raw GPS data (2017)

#16

Post by AlexanderTheGr8 »

cmsj wrote: post #12
AlexanderTheGr8 wrote: post #10

Earlier quoted context omitted.

Can you explain what you mean by that? The only thing I can think of is that GPS has 2 modes : one civilian and other military use. But military use-case uses encryption so civilians can't use that mode anyway.

GPS was built primarily for the military and the signals available for civilian use were crippled to reduce accuracy. GPS receivers that provided high accuracy fell under the ITAR rules (ie you needed proper licensing to trade them) Over time such restrictions have largely been lifted, but there are still US export controls on GPS receivers with particular features, such as those designed for use in high speed aircra…

> those able to decode the still-military-only encrypted signals

How? I was under the impression that military-only signal was encrypted. And if someone breaks that encrpytion, blame should go to the poor handling of encryption rather than the person breaking it? Analogy : if you leave a classified document on the train and a passenger reads it, whose fault is it?

Re: Calculating position from raw GPS data (2017)

#17

Post by nobodyknowin »

AlexanderTheGr8 wrote: post #15
nobodyknowin wrote: post #14

Earlier quoted context omitted.

Not GP but modern GPS / GNSS manufacturers intentionally do not allow their devices to function over some speed (1000 mph or something like that). So they won't work on warheads as part of a guidance system.

I never really thought of that. That's a pretty interesting restriction. Although any party with access to warheads that can fly 1000+ mph probably can bypass the GPS restriction, no?

Not if they buy an off-the-shelf solution.

Re: Calculating position from raw GPS data (2017)

#18

Post by m463 »

AlexanderTheGr8 wrote: post #15
nobodyknowin wrote: post #14

Earlier quoted context omitted.

Not GP but modern GPS / GNSS manufacturers intentionally do not allow their devices to function over some speed (1000 mph or something like that). So they won't work on warheads as part of a guidance system.

I never really thought of that. That's a pretty interesting restriction. Although any party with access to warheads that can fly 1000+ mph probably can bypass the GPS restriction, no?

Just don't let some future party use your code to do it.

Re: Calculating position from raw GPS data (2017)

#19

Post by j16sdiz »

AlexanderTheGr8 wrote: post #16
cmsj wrote: post #12

Earlier quoted context omitted.

GPS was built primarily for the military and the signals available for civilian use were crippled to reduce accuracy. GPS receivers that provided high accuracy fell under the ITAR rules (ie you needed proper licensing to trade them) Over time such restrictions have largely been lifted, but there are still US export controls on GPS receivers with particular features, such as those designed for use in high speed aircra…

> those able to decode the still-military-only encrypted signals How? I was under the impression that military-only signal was encrypted. And if someone breaks that encrpytion, blame should go to the poor handling of encryption rather than the person breaking it? Analogy : if you leave a classified document on the train and a passenger reads it, whose fault is it?

Technological restrictions and Legal restrictions not always aligns.

That's where the "restrictions have largely been lifted" part comes in.

You can decrypt most of them, but it is illegal to export without a license.

Post reply on HN