This is what I was talking about / asking about last year.?ÿ Not what I had in mind, but they are saying it is possible to do positioning from the Starlink constellation with a software upgrade.?ÿ You KNOW the military is interested in this for a GPS backup, as they are already heavily interested in Starlink for military comms.
I have to wonder what the received signal strength would be, and the processing power needed to compute a position from the number of sats that will be above very very soon.
https://telecomstechnews.com/news/2020/sep/28/starlink-satellites-robust-navigation-gps/
The signal advantages are pretty clear (no pun intended), but I don't think the UT paper is focused on obtaining survey-grade precision.
Here's the chart they throw out:
Yeah, even if you totally ignore that the authors are ignoring SBAS, the LEO numbers look pretty good in comparison. But still not survey-grade.
Real-time positioning relies heavily on broadcast/predicted orbits and clock offsets. I am given to understand that low-earth orbits are inherently unstable and thus hard to track in real-time or predict, and that there are no plans for high-grade clocks on LEO constellations.
The authors claim to be able to solve this problem...
"one may exploit the plentiful data bandwidth present in each broadband satellite transmission burst for up-to-the-instant orbit and clock products. If such zero-age-of-ephemeris products are available, then the need for atomic clocks in LEO may be eliminated. Second, one may obtain these orbit and clock products by performing precision orbit determination(POD) on-orbit using traditional GNSS in a multi-tier architecture"
...although I'm not sure what that means because I ain't that smart.
Are they saying that the chart is representative of the result after the above wizardry has been implemented?
Because (a) that's pretty darn impressive, but (b) I still can't meet most survey specs with those precisions.
Could we possibly use it to supplement traditional GNSS, and come up with a position that is better than either one on their own?
My hope is that starlink will allow for a better connection when using a network rover, especially in places with no cell signal. The issue there is will you be able to get access with a data collector or similar device?
Your data collector will not be able to log into starlink, but you should be able to connect to a mobile base station - you will need a dish to connect to starlink.?ÿ It assume it would be similar to the RTK bridges that are already available, you just will be using a dish instead of a cell.
You have to think that some sort of hybrid system is going to be pretty robust, and benefit from the precision of GPS/GNSS & the signal strength of Starlink.
?ÿ
My original idea was to tie an atomic clock into starlink, but they specifically say that is not needed.?ÿ Hell if starlink has GPS receivers (which I am 90% sure they do) I had to wonder if re-broadcasting that signal would help?
Starlink direct-to-cell data service is scheduled to start in 2025. This will not require a dish or any special hardware and this will be a game changer for RTK surveying. You will be able to use TCP corrections between your base and rover and never have to worry about radio or cellular coverage again.
Would signal latency be an issue?
No, latency should not be an issue. Starlink has a median latency of 20 milliseconds now.
https://api.starlink.com/public-files/StarlinkLatency.pdf
Many of the LEOS not all but some are already using GPS to determine their positions in a near real time type environment. That could be the solution to poor clocks. For RTK. The URE is a bit tricky as well. But doable. Some ground monitoring stations geographically could aid as well. I see many solutions and many cons to those very solutions as well. But anything is possible.