Sea ports used to broadcast a local correction signal[1] back when GPS was intentionally less accurate. Seems like an oversight that farms don't have their own correctors.
SparkFun has some kits in this space, but you can easily pay up to $10k or more for a more commercialized system that is designed for surveying, or other related purposes.
If that's really true then what the was even the point of building Galileo HAS then? I swear these things could not be more confusing.
As other have said can do a local install. A pair of RTK receivers is only $500. But you need a connection between the base station and the tractor. These farms are pretty flat so perhaps perhaps technically it's not so difficult with LORA. But these are farmers, not hackers, and perhaps it has to talk to the tractor, and perhaps the tractor is made by John Deer. It all gets very hard very quickly.
In the mean time SBAS was a off the shelf solution the dealer could sell to everyone because it worked everywhere in the country. Until it didn't.
Trouble is, that (and Galileo HAS) assumes you have internet access. Maybe you're so far out in the middle of nowhere (This is Australia we're talking about in TFA) that the internet isn't available, or reliable.
So maybe you think satellite-based corrections are the way to go, but I concur, a local RTK reference would also work. (But 99.9% of the time, the satellite service is gonna be less hassle.)
Differential GPS, by contrast, transmits the difference between the surveyed location of a base station and the GPS-derived position of the same station. That offset can be used locally to correct other nearby GPS receivers.
Phones also use trilateration on the cell tower signals to get an approximate solution before trying to solve 3d+time on the GPS signal.
I may be wrong, but I don't know of any system for cell-tower derived corrections being redistributed out as GNSS corrections. Could you clarify the specific system you described?
AGPS is used when satellite coverage is poor, like urban canyons in a city, also a situation where there are a lot of cell towers and triangulation is somewhat useful
I think what you're referring to with cell tower triangulation (and also WiFi location, etc.) is generally referred to as "hybrid location service" and is usually done at a higher level (ie - in software) using AGPS as one input to a sensor fusion algorithm.
Once this is available, the receiver can then focus on the signals that are expected and will then be able to provide a 3D fix as soon as it receives something from 4 satellites, which would be in a few seconds.
Easily maybe.
I can’t see any reason someone can’t take a stationary GPS enabled device and use that to broadcast the differential between received location and actual location. Probably could do it for less than $20 in equipment. Add multiple units and get triangulation for free.
That is enough movement that it can throw off purely GPS solutions.
https://www.australiangeographic.com.au/topics/science-envir...
> ...
> But two important things have happened since then. Australia has moved about 1.6 metres northeast, effectively moving the location of mapped features and their associated GDA94 coordinates.
> At the same time, positioning technology has evolved considerably. By 2020, Australia will have moved by 1.8 metres and many of us will own devices that could pinpoint locations with accuracy as small as, well, a smartphone. With real-time access to precise satellite positioning at our fingertips, we’ll notice discrepancies with GDA94-mapped features.
> Imagine the confusion if a driverless car can determine its coordinates with (say) decimetre accuracy, in the GNSS datum, but the stored map features were referenced to our old datum GDA94 and and were nearly two metres different. That’s probably not even in the same lane.