I'm wondering whether it actually matters to people whether their GPS device has 2, 4 or 7m accuracy. Anything with lower resolution than about 5 cm is going to be largely useless for robotic driving, etc, particularly anything worse than 2 m res - so really (and not meaning to be rude to you and your research efforts) - isn't the different resolution irrelevant, and isn't the only reason GPS users should be happy about GLONASS integration is redundancy (especially in the rare military event that the US decides to switch public GPS off?)
Computer driving is more about vision systems than GPS. Maps certainly aren't accurate into the centimeter range in any event.
Sailors find that their charts are some times off by kilometers. I've personally seen a large, erroneous discontinuity in the western coast of St. Lucia while using a GPS chart plotter for navigation. Chart data is copied forward from older charts, many of which were made in the 1800s, those guys were good with a sextant, chronometer, and a pen, but when near land you need your eyeballs.
It means more satellites in the constellation(s), and in circumstances where that makes the difference between getting a GPS/GLONASS fix and having to rely on cell tower/WiFi positioning then the difference in accuracy would be very significant.
I'm not talking about the entire system failing and falling over to the other, I'm talking about the probability that from any given point you can see enough satellites to get a fix. More satellites is better.
I would love it if I could use "find my iPhone" inside my house without having to resort to the audible alert when other people are sleeping. So, yes, better resolution would be wonderful. Edit: and to address the obvious objection, no, the current resolution is not good enough for this. With the current accuracy, I'm not able to locate my phone within my house yet (iPhone 4, and no canyon issues here).
Anyone tested iPhone navigation in a gps blackout area (e.g. Near an air force base?). I used to live in Lompoc and GPS wouldn't work in most of the town owing to the proximity of Vandenberg AFB.
I wasn't aware there of existence GPS blackout areas anywhere, esp. in the continental United States. Do you have more information that would support your statement?
So, what exactly happens there? Your device stops seeing satellites (loses lock)? Or does the reported uncertainty become on the order of hundreds of meters? Or does it simply give you confused directions when you're driving?
Searching for combinations of terms like "GPS, blackout, airforce base, lompoc" only brings up this thread. I find it hard to believe that if it were a real occurrence no one else would notice and write/complain about it.
