3 ms·

There are academic papers on using multiple smartphones to synthesize centimeter accuracy based on smartphone typical meter-scale accuracy. Apparently the obvio

by Zigurd 3y ago

There are academic papers on using multiple smartphones to synthesize centimeter accuracy based on smartphone typical meter-scale accuracy. Apparently the obvious approach, which is calculating a dual frequency-based position, which is what survey GPS does, is not available from smartphone GPS, even though Android APIs give you access to signal phase data. I suppose if you had more than one phone you could do better. But "crowdsourcing" seems like a stretch. Why? What's the TAM? What's the business model? What are the use cases? The article mentions anonymization, but that just points out the privacy concerns about participating in a thing that depends on you sharing location data, however obfuscated, with strangers. I could see Qualcomm buying the patents, if any, for beamforming 5GSA optimization.

nix0n 3y ago
Regular GPS claims ~1m accuracy, but in urban areas it's really more like ~10m, and it gets confused about which side of the street a pedestrian is on. If you have a dozen people trying to navigate the same neighborhood of Boston* on foot, they could all be using the same app, all sharing data with each other and all benefiting from that data. Does phase data require holding the receiver still? Anytime I've seen a survey GPS receiver, the surveyors seem to leave it in the same spot for a few minutes. *There's some loss of generality here. In a grid layout place like New York this would be unnecessary, but in a less dense place it would be unviable.
- bcrl 3y ago
  I use hardware that collects RTK corrected GPS coordinates for pole line engineering, and even with RTK you can get some pretty wild errors. One building in a small town with a metal roof and metal siding caused the reported location of the adjacent pole to be more than 10 meters off. I ended up manually correcting the coordinates via the satellite view on the map. I've seen cases where inaccurate positioning of poles by just 60 centimeters is enough to make pole loading analysis fail a pole.
mindslight 3y ago
I'd imagine there is at least something to be gained from calculating position/velocity patterns of receivers (stationary on a desk, moving on a road in a car, etc) and then cleaning up data based on that. Or perhaps the goal is to use data from dual freq GPS receivers to helping out the continuing majority of single frequency receivers? Or perhaps they are just leaning on fixed base stations in urban areas to "bootstrap" and focusing on the P2P aspect as marketing, plus a convenient permissions grab for backhauling personal location information.

by Zigurd 3y ago

nix0n 3y ago

Regular GPS claims ~1m accuracy, but in urban areas it's really more like ~10m, and it gets confused about which side of the street a pedestrian is on. If you have a dozen people trying to navigate the same neighborhood of Boston* on foot, they could all be using the same app, all sharing data with each other and all benefiting from that data. Does phase data require holding the receiver still? Anytime I've seen a survey GPS receiver, the surveyors seem to leave it in the same spot for a few minutes. *There's some loss of generality here. In a grid layout place like New York this would be unnecessary, but in a less dense place it would be unviable.

bcrl 3y ago
I use hardware that collects RTK corrected GPS coordinates for pole line engineering, and even with RTK you can get some pretty wild errors. One building in a small town with a metal roof and metal siding caused the reported location of the adjacent pole to be more than 10 meters off. I ended up manually correcting the coordinates via the satellite view on the map. I've seen cases where inaccurate positioning of poles by just 60 centimeters is enough to make pole loading analysis fail a pole.

mindslight 3y ago

I'd imagine there is at least something to be gained from calculating position/velocity patterns of receivers (stationary on a desk, moving on a road in a car, etc) and then cleaning up data based on that. Or perhaps the goal is to use data from dual freq GPS receivers to helping out the continuing majority of single frequency receivers? Or perhaps they are just leaning on fixed base stations in urban areas to "bootstrap" and focusing on the P2P aspect as marketing, plus a convenient permissions grab for backhauling personal location information.