Existing GPS, GLONASS, GNSS, etc. isn't slightly imprecise because of ability, it's because of signal propagation. If you're receiving a reflection or your signal is blocked by a building, you lose accuracy. But given the number of services in orbit, and the number of satellites, adding Starlink to them won't really change anything. More satellites doesn't really mean more accuracy here.
There's also basically zero chance the military would actually use any such signal for navigation, regardless of SpaceX allowing or not. SpaceX isn't known for reliability. Aaaand since they've been talking about bankruptcy for two years now, it's probably a really bad idea to lash yourself to that particular anchor. GPS (and international competitors) is funded not only commercially but by the government. It's not going to stop working, it's not going bankrupt, it's not run by a weirdo that might just turn it off because someone didn't say something nice about him today.
As for mobile phones working, SpaceX announced their research work with T-Mo to get ahead of Apple's announcement. They're still in extremely early stages, and it's really only useful for SMS sized messages once every half hour or so. Basically, good for emergency use like "I fell off a cliff and need help".
This post is hypothetical on what is possible not what are they doing commercially right now. I appreciate you attempt to limit my discussion to what is proven possible with commercially available products. Per the articles that I have posted, if they are believed, everything I discussed has been tested by researches as possible right now and could be commercially viable products within a few years.
From your responses it seems like you did not read the articles I linked to.
The entire country of Ukraine is relying on the signal accuracy of Starlink to make military strikes everyday, has not been reported they have any significant problems at this point. I'm not aware of the current reliability of the Starlink signal, but I have no doubt within the next few years with all the research going into it, the robustness will no doubt improve even with more users.
For GPS you don't need a strong data feed, just enough to receive the timecode signal which is less than 1KB. When you are talking about reliability as a data provider, the timecode signal is being constantly sent down from the satellites regardless of how much data is being transmitted back and forth.
According to the article I read the US Military has already approached SpaceX to use the signal for navigation and was turned down. Much harder for a country to destroy 3,000 starlink satellites vs the current 30 we have for GPS. Robust backup is something you need when fighting a war. Taking down 30 satellites would be all in a good days work for some countries we could go to war with. Destroying 3,000 satellites sounds like a multiyear effort.
I have no doubt that Spacex could launch enough satellites fast enough to overcome any amount that may be shot down.
The article states the existing signals coming from Starlink satellites has already been used as a defacto GPS by MIT researchers without any assistance from SpaceX, It is nearly as accurate as existing GPS and with some tweaking over time will be as accurate as the current GPS systems based on what is said in the article.
My point was not how much information could be transmitted by a cell phone, but that the antenna within a cell phone is large enough to receive the signal from SpaceX satellites for GPS purposes. SpaceX has confirmed this. Receiving a signal from a Satellite for GPS geolocation purposes does not require transmitting to it from the ground and has nothing to do with the amount of bandwidth the satellites or small antenna can support.
They said with more development you would be able to make emergency phone calls with the bandwidth, but they are starting out with SMS which is easier and obviously could support a much larger number of users until they can get more satellites supporting this service in the sky. Apparently the bandwidth of the entire satellite cell area is around 2MB per second. A phone call takes something like 7KB per second according to Elon. Even without the Gen2 satellites needed for this emergency service they can already use the current satellite signal as a GPS.
Any new company burning through as much capital as SpaceX is going to risk bankruptcy the first decade or so, discussing it and what must be done to avoid it is only rational. However I would be willing to bet that like Tesla, SpaceX is going to be one of the most profitable 5% of companies in the world over a ten year period at some point soon, count on it. Too bad for us SpaceX is a private company.
I don't think bankruptcy is a concern, but even if they do go bankrupt, those satellites are still going to be sending down a signal for several years until they are directed to fall out of the sky, no further money needed. The satellites based on their closeness to the planet would orbit for at least 5 years, before Tesla may direct them to deorbit. In a war no doubt the US government would prop up SpaceX single handedly just to guarantee a GPS signal.
I appreciate you think Elon is a weirdo, however he is going to direct a couple trillion dollars in revenue over the next few years, guess he is sane enough for most. I don't really no too many other than maybe some Saudi's and Tim Cook that currently have more responsibilities for commerce on a dollar basis.
Elon is not perfect, but no doubt you would agree he is out there trying to accomplish some good in the world everyday and is more effective at making a positive impact besides selling alot of cars everyday than most.
Also saying you want to shutoff a signal as a tactic to remind people what you bring to the table after some insults is completely different than actually doing it.
-Spacex thinks there is some advantage to having GPS on Starlink, since they are applying for trademarks per the articles.
-The US military is asking for it, MIT Reseaches have concluded Starlink is already a working GPS system close in accuracy with existing GPS with no development needed. The ground hardware they built to test it could be improved to match the accuracy of current GPS with further tweaking per the researchers.
I can appreciate some of your points.
What I said hypothetically has been proven possible by researchers, has some advantages in war due to the unmatched number of sattelites, and most likely for other reasons based on moves by SpaceX to trademark. Enough Said.