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We built a new GPS receiver engine

blog.coresemi.io

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Re: We built a new GPS receiver engine

#91

Post by 0xffff2 »

willis936 wrote: post #14
epanchin wrote: post #6

Earlier quoted context omitted.

The speed limit in the US is 1000mph, else it’s a munition. I believe the US used to make their GPS slightly inaccurate, but this was done on the satellite side.

I find a bit of humor in imagining NASA rocket launches and atmospheric test vehicles being viewed, in some contexts, as a munition.

I'm a software engineer at NASA and it's an annoying fact of life for us every day. There's a huge overlap in the technology, we just have different applications. In fact, a huge percentage of our airplanes are aircraft military aircraft.

Re: We built a new GPS receiver engine

#92

Post by pps43 »

numpad0 wrote: post #39
willis936 wrote: post #14

Earlier quoted context omitted.

I find a bit of humor in imagining NASA rocket launches and atmospheric test vehicles being viewed, in some contexts, as a munition.

Russians call everything a rocket anyway. RPG-7 is a rocket, Saturn V is a rocket, Sidewinder is a rocket. They’re not confused about it, they regard all to be in the same category. It’s a bit political than technical that in American English guided rocket weapons are always called “missiles“. Same reason as J in NASA JPL stands for _jet_ though they don’t normally do turbine jets. So calling non-military rockets as…

> Russians call everything a rocket anyway. RPG-7 is a rocket

Bad example. РПГ is "ручной противотанковый гранатомёт", approximately "man-portable anti-tank grenade launcher". Its round, "ПГ-7" is "anti-tank grenade". Rocket-propelled grenade is a backronym.

Re: We built a new GPS receiver engine

#93

Post by tezzer »

gsnedders wrote: post #65
opencl wrote: post #63

Earlier quoted context omitted.

They indicate plans to sell hardware on Crowdsupply which is based in the US. Presumably this is going to be FPGA-based which brings up all the fun questions of how ITAR applies to software. Would adding a speed restriction in their VHDL that could be trivially bypassed by patching out one line of code satisfy ITAR requirements? AOSP has this sort of code in it (search for ITAR_SPEED_LIMIT): https://android.googlesou…

> Presumably this is going to be FPGA-based which brings up all the fun questions of how ITAR applies to software. I mean there's plenty of prior art with open-source crypto implementations here.

Crypto is its own category in the ITAR, one whose impact decreased over time as events made the restrictions less relevant. Most crypto is now EAR not ITAR, but treated as a special category. I'm not sure the software classification lessons are going to apply.

Re: We built a new GPS receiver engine

#94

Post by salty_biscuits »

bjt2n3904 wrote: post #80
Arjuna wrote: post #68

Earlier quoted context omitted.

The speed limit in the US is 1000mph, else it’s a munition. Please note: my apologies in advance for a comment that may be perceived as pedantic, but I just wanted to further illuminate this statement. The U.S. regulation, which technically falls under the Export Administration Regulations (Navigation and Avionics), does not exclusively regulate GPS navigation in munitions applications; rather, it serves to regulate…

According to Google, the F22 can do 1500 mph. Looks like civillian GPS is still good as long as you keep it under Mach 1.8 at sea level ;) ICBMs on the other hand, reportedly go ten times the speed of an F22.

Is is really for missiles. Same reason the ITAR limits for accelerometers and gyros are relatively high (I think like 10g for acceleration). Same again for vibration tolerance. It is a barrier to entry for making a navigation system for missiles.

Re: We built a new GPS receiver engine

#95

Post by lgats »

sevenf0ur wrote: post #3

> Well, how about deliberate dilution of precision or intentionally limiting the speed the GPS chip can be used at? Is that a legal requirement or just done on request? I sort of chuckle whenever I hear of limitations like that being put in place as if someone that can construct an ICBM is going to be constrained by the GPS module.

See "COCOM Limits" https://en.wikipedia.org/wiki/Coordinating_Committee_for_Mul...

Re: We built a new GPS receiver engine

#96

Post by lgats »

durkie wrote: post #61

Mostly off-topic here, but it seems like the best place to get an answer: several years ago in my lab at Georgia Tech, a technician I worked with said he had a friend who invented a device for doing celestial navigation, but that it 1) worked in the daytime somehow and 2) used digital technology so that it was more precise than a sextant / traditional celestial navigation. The technician was prone to a bit of exagger…

See Also https://en.wikipedia.org/wiki/X-ray_pulsar-based_navigation

Re: We built a new GPS receiver engine

#97

Post by rasz »

azinman2 wrote: post #90

It seems like they did this for SpaceChain, which I had never heard of before. I read their information, taking about combining blockchain-technology and satellites, and I'm still very confused. Other than buzzwords, what is this actual business and why is the blockchain necessary here? dApps in Space? What? Why?

attracting VC suckers of Softbank caliber

Re: We built a new GPS receiver engine

#98

Post by ChuckMcM »

This is super cool, its nice to see this come out of the idea stage into something one will be able to buy. I find the most use for gps modules is time data, I have one outside my window that is feeding a PPS signal into a server running ntpd. Saves me from bothering internet ntpd servers.

Re: We built a new GPS receiver engine

#99

Post by gsich »

PaulHoule wrote: post #22
gsich wrote: post #19

Earlier quoted context omitted.

You can get multiple devices and compare the output. Doesn't give you absolute accuracy of course. But you can set one as "master" and diff to that.

I dunno. Back in the day when "selective availability" was turned on they added "brown noise" with strong low frequency components that would defeat attempts to use temporal averaging to approve GPS accuracy. I remember setting a receiver up outside and looking at the tracks go in circles like a spirograph.

Selective availability is off since almost 2 decades.

Re: We built a new GPS receiver engine

#100

Post by wwkeyboard »

cptskippy wrote: post #58
sevenf0ur wrote: post #3

> Well, how about deliberate dilution of precision or intentionally limiting the speed the GPS chip can be used at? Is that a legal requirement or just done on request? I sort of chuckle whenever I hear of limitations like that being put in place as if someone that can construct an ICBM is going to be constrained by the GPS module.

It seems silly in today's world where anyone can roll a custom SoC and have it spun out by any number of Fabs over the weekend, but 30 years ago custom chips were pipe-dreams for all but the most advanced tech firms. The $2 microcontroller you use to turn your lamp on has more processing power than a desktop computer from the early 80s. By putting artificial constraints on off-the-shelf GPS technology, it forced bad…

I thought SA was removed because we discovered ways around it. Specifically differential GPS(tl;dr is that if you have a known point on the ground you can take a measurement there and get the SA offset, this is widely used to compensate for atmospheric error in GPS).
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