gps home point

Hello! I apologize if this topic seems redundant, but I would like to gather research on what the minimum amount of satellites you personally need for your Phantom's home point to be updated? I realize that there are a lot of threads that discuss this, but from what I've seen, there really...

Sorry if this question is redundant. If I'm out in the middle of nowhere with no cell service, will my phone still record a new gps home point? Will return to home still work? And finally, do I need to cache my maps beforehand? If so, how does one do that on an iphone? Thanks!