https://kaisercougarconnection.com/2784/news/musical-trains-...
My impression is that all of the Yamanote line stations are above ground -- I'd have expected it to be possible to have "one button plays the right sound at each station" if you used a standard phone's GPS to figure out which station you were at.
Kids these days...
Not only you don't need a GNSS to determine a fixed in place railroad station but actually you don't want to use a GNSS to do that.
A simple radio beacon working on ~400MHz is more than enough to solve this difficult technical obstacle.
Of course, this is totally ignoring what the trains do already know where they are because they need to display the current/next stations on the passenger information displays.