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Super-Accurate GPS Chips Coming to Smartphones in 2018

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Re: Super-Accurate GPS Chips Coming to Smartphones in 2018

#171

Post by lucb1e »

sschueller wrote: post #152
gruez wrote: post #4

>will give the next generation of smartphones 30-centimeter accuracy instead of today’s 5-meters Didn't the US scramble the civilian signals specifically so it wouldn't be too accurate? And they're just okay with civilians having access to ultra accurate GPS receivers?

I don't see the point. You can just use a bigger bomb to overcome the inaccuracy.

Way to lose support from your own people.

I do see the point of the intention, but as far as I understand it, it never really worked for preventing that anyway.

Re: Super-Accurate GPS Chips Coming to Smartphones in 2018

#172

Post by 24gttghh »

Crosseye_Jack wrote: post #145
24gttghh wrote: post #140

Earlier quoted context omitted.

Is there not still a limit to GPS accuracy when civilian receivers go beyond a certain speed? e.g. to deter clandestine missile development?

iirc the requirements are an AND condition for speed and altitude. >1,000 knots AND >18,000m. But many civilian receivers implement it as an OR condition much to the annoyance of the near space balloon community. Some will even switch of the radio once one of these limits are reached and not enable it until it's been reset so make them a pain to use for even if you just wanted the location data after your payload com…

Leave it to stackexchange to shed some more light on the matter[0].

The original limits appear to be for units available for export, but I would guess manufacturers didn't want to deal with the headache of producing different models for import/export and just slapped the restriction down on everything. The poster does claim the original restriction was indeed an OR[1].

And current restrictions may only be 600 m/s? [2]pg 58

[0]https://space.stackexchange.com/questions/14687/current-situ...

[1]https://www.ngs.noaa.gov/corbin/class_description/5700-5800V...

"Immediate access to satellite measurements and navigation results is disabled when the receiver’s velocity is computed to be greater than 1000 knots, or its altitude is computed to be above 18,000 meters. The receiver continuously resets until the COCOM situation is cleared."

[2]http://mtcr.info/wordpress/wp-content/uploads/2017/07/MTCR-T...

Re: Super-Accurate GPS Chips Coming to Smartphones in 2018

#173

Post by jandrese »

noen wrote: post #104
dmckeon wrote: post #27

Down to 30cm - good! Now all we need is a GPS-enabled app for urban pedestrians that reminds them to look left or right just before they step off a curb into oncoming traffic.

Actually, I was part of a team that built a GPS based walking navigation system for the blind (Google Microsoft Cities Unlocked). The limits of 5m accuracy were an incredible danger that prevented us from doing any u assisted trials. Even highly trained and skilled cane users would wander into the roadway usually within 10-15 minutes of using the system, purely because of GPS drift. And forget about ever using it in…

Road navigation apps only work as well as they do because they lock your position to the road and assume no excessive changes in velocity.

Re: Super-Accurate GPS Chips Coming to Smartphones in 2018

#174

Post by zwieback »

matt_kantor wrote: post #53

Why was "oil and gas exploration" an early adopter here? Can anyone connect the dots for me? I wouldn't expect interesting oil/gas pockets to have <5m lateral diameter, but then again I know very little about that industry.

Seismic exploration of new oil fields requires both accurate geographic and, maybe more importantly, accurate time synchronization. If you place a ton of sensors in the ground and then pound the ground or set of explosives you need to know exactly where and when the echoes of the sound waves were picked up.

Re: Super-Accurate GPS Chips Coming to Smartphones in 2018

#175

Post by drdrey »

unfamiliar wrote: post #98
drdrey wrote: post #63

Earlier quoted context omitted.

It also has the potential to greatly increase the accuracy of the instant pace, which is a lot more volatile than the total distance

I mean, how erratically are you running? My pace wouldn't vary much over a typical 200m.

That's my point, even if you run at a steady pace the instant pace reported by your device tends to jump around quite a bit, even if they smooth it out over 10s. On my Garmin watch, the instant pace typically jumps around by +-20s/mile, which is significant when you're trying to hit a specific pace target.

Re: Super-Accurate GPS Chips Coming to Smartphones in 2018

#176

Post by mkstowegnv »

JshWright wrote: post #121
antonioalegria wrote: post #102

How does this compare with iPhone 8/X, which supports the Galileo system, as well as GPS and GLONASS?

The vast majority of phones out there support GPS and GLONASS (as well as ESA's Galileo), and have for years. That's not new to the iPhone 8 (surely the iPhone has has this before as well, right?) Using the other constellations helps you see more sats, but it doesn't really help deal with the reflection issue in urban environments. The "big deal" about this chip is that is uses the new L5 signal (and it's equivalent…

Gallileo support in new cell phones only barely started this year https://www.gsc-europa.eu/galileo-gsc-overview/services/gali...

Re: Super-Accurate GPS Chips Coming to Smartphones in 2018

#177

Post by JshWright »

mkstowegnv wrote: post #176
JshWright wrote: post #121

Earlier quoted context omitted.

The vast majority of phones out there support GPS and GLONASS (as well as ESA's Galileo), and have for years. That's not new to the iPhone 8 (surely the iPhone has has this before as well, right?) Using the other constellations helps you see more sats, but it doesn't really help deal with the reflection issue in urban environments. The "big deal" about this chip is that is uses the new L5 signal (and it's equivalent…

Gallileo support in new cell phones only barely started this year https://www.gsc-europa.eu/galileo-gsc-overview/services/gali...

Yeah, hence the parenthetical addition. GPS and GLONASS have been around for quite some time though.

Re: Super-Accurate GPS Chips Coming to Smartphones in 2018

#178

Post by mookerji »

LeifCarrotson wrote: post #156
phkahler wrote: post #136

Accuracy vs Precision. So they can pin your position to within 30 centimeters, but how small of changes can be detected? Can they detect relative movement on the order of 1cm or less? that would be really useful for some things. For example if you wanted to measure the distance between 2 points on the ground, you don't care about offsets but do care about precision.

Check out the documentation from Swift's Piksi receiver project for a good introduction to existing technology: https://www.swiftnav.com/sites/default/files/whitepapers/loc... The technology in good receivers like the Piksi is slowly drifting into consumer-level hardware. You need to correct for such errors as: 1. Jitter in the code phase vs. phase-locked-loop. As the article describes, most existing codes are long a…

(disclosure: I'm an engineer at Swift Navigation)

Indeed, carrier phase and multi-frequency+constellation measurements are drifting into consumer hardware, but I can say that it's probably going to be a Good Long While before we full realize its benefits. The use of cell phones (and cheap cell phone antennas) is an active area of research, particularly for organizations aiming to make high-accuracy GNSS positioning widely accessible outside of specialty markets (i.e., agriculture and surveying). It's an interesting area to be in for sure:

  - http://gpsworld.com/innovation-precise-positioning-using-raw-gps-measurements-from-android-smartphones/
  -
 https://radionavlab.ae.utexas.edu/images/stories/files/papers/inPhoneCdgnssIonPlans2016.pdf
The base station network density question @ac29 points out later is a compelling reason for some of this.

(Shill: We're hiring for firmware engineers right now, focused on a variety of different areas: embedded Linux, DSP basebands (C), and navigation algorithms (C++) design and implementation. See https://jobs.lever.co/swift-nav for more details or email jobs@swiftnav.com.)

Re: Super-Accurate GPS Chips Coming to Smartphones in 2018

#179

Post by ufmace »

philipkglass wrote: post #20
gruez wrote: post #11

Earlier quoted context omitted.

But that's client side right? What's preventing someone from implementing a GPS receiver using a SDR that doesn't have those restrictions?

Nothing at all: http://www.aholme.co.uk/GPS/Main.htm

That's really cool! I'd like to build something like that One Of These Days, when I have more free time.

Also gives you the point - if one guy can build a receiver on his own... I mean, I don't want to make it easy for rogue nations and terrorist groups to get ICBM-mounted nuclear weapons, but with the difficulty of building and testing the missiles and bombs, it seems a little silly to expect restricting GPS receivers to accomplish anything.

Re: Super-Accurate GPS Chips Coming to Smartphones in 2018

#180

Post by jhayward »

LeifCarrotson wrote: post #156
phkahler wrote: post #136

Accuracy vs Precision. So they can pin your position to within 30 centimeters, but how small of changes can be detected? Can they detect relative movement on the order of 1cm or less? that would be really useful for some things. For example if you wanted to measure the distance between 2 points on the ground, you don't care about offsets but do care about precision.

Check out the documentation from Swift's Piksi receiver project for a good introduction to existing technology: https://www.swiftnav.com/sites/default/files/whitepapers/loc... The technology in good receivers like the Piksi is slowly drifting into consumer-level hardware. You need to correct for such errors as: 1. Jitter in the code phase vs. phase-locked-loop. As the article describes, most existing codes are long a…

> 3. Unknown, slowly drifting ionospheric delay.

Iono delay is typically corrected by using a dual-frequency receiver so that it can be calculated directly via difference in arrival times of the time pulse on each frequency. L2C can help here.

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