> The GPS issues have nothing to do with getting a GPS fix. It's just a plain ol' bug.
GPS on phones aren't that accurate, especially downtown, but most applications will filter the data because of that. Ever use Google Maps for directions and make a turn different from what the app is telling you to do? Your car icon will continue down the "correct" path for 15-30 seconds before re-adjusting to the new route. This actually happens all the time, it's just more likely that your GPS is misreporting you as 20m east instead of you taking a different turn, so the app holds off on updating the display until it is more sure.
So it's a combination of the two factors. But most apps handle it muuuuch better than P:GO does.
Here's a link I was able to find on running apps specifically. Apps that deal with you being on foot will obviously have a harder time determining exactly where you are, as opposed to apps for driving where you're moving faster, in a straight line, and down a grid of streets.
> I had a phone with broken gps and I didn't really notice.
I certainly noticed in the UK on an iPhone 6 where the GPS chip was borked. You would drive for 10 minutes and then you would get an updated location. This was in outer London.
> and my phone has no problems finding GPS and I have navigation instructions pulled up in about 5 seconds.
That's because your phone isn't actually using GPS ( e.g. Navstar or Glonass ) at that point, it's using cell triangulation or wifi-based location.
For example the fastest possible first-fix with Navstar from a warm-start, using cached prior-location and ephemerides, is 30 seconds[0]. From a cold ( position-unknown ) start, such as a car nav-system powered-down in a parking-lot for an extended period, the first-fix will take longer than 12 minutes. There is no technological way around that, it is an artifact of the system architecture.
[0] and that's for a top-end receiver than can sync to four satellites 'simultaneously' using time-division.
> After about a kilometer I have to cross a busy street, I need to pause there regularly. Pausing always fixes erratic mode.
Given that the “erratic mode” only impacts the beginning of the run and disappears suddenly at known locations, this sounds like an issue of delayed GPS lock.
And given that the problem didn’t exist in the past, it could be a software issue due to upgrades. Or it could be a hardware issue that developed over time, such as something impacting GPS receive sensitivity. Or it could even be a new source of RF interference in the GPS range near the author’s start point, which impacts GPS lock until they get far enough away from it.
Interesting issue, but note that this issue appears to be specific to this one specific person, not a general issue with all Apple Watches as some in this thread are speculating. I certainly have not noticed this behavior on my Watch even with the latest updates.
> GNSS accuracy is poor in forests, canyons, and dense urban environments
I feel like this should be solvable on the software side, especially for medium or long distance runs. If I look at the traces, I can see that the recorded zig-zag is obviously wrong, and a bit of smoothing should be able to fix it.
I'd expect someone that concerned about their GPS tracks to be using a dedicated GPS device (Garmin, Polar, Suunto, etc.) rather than an iPhone - they're just not reliably up to the job regardless of road-snapping (which I've never triggered when walking...)
> everything suddenly shifts 10 (or 50) meters to the east because your device got updated GPS info.
Seems like you could 'debounce' GPS updates where you know it hurts to make changes. Not that different from maps' cheating. But the resolution of GPS and its challenges related to ground clutter will always be a thorn in the side of AR applications like this one.
> That GPS signal is susceptible to fluctuations based upon which tower is “visible” (A-GPS). I’ve had it happen where I go through tunnel and the phones GPS thinks I’ve magically run a mile in the opposite direction. Some of my Strava traces look like they are all scribbles.
That might explain one of my rides having a spurious "cliff climb" where the altitude went bonkers.
That being said, I lost interest in Strava when they killed the Bluetooth integration with my Wahoo TICKR. That was just another of the incessant reminders of why I can't trust tech companies anymore.
The GPS issues have nothing to do with getting a GPS fix. It's just a plain ol' bug. My GPS is spot-on when using any app other than Pokémon Go which pretty regularly states that the GPS isn't working when I'm holding my phone in my hands to an open sky with no clouds.
It doesn't matter what I'm doing or what device I'm using it always shows that GPS error message every 30 seconds to 1 minute.
> getting a GPS fix through network assistance still sends data to Google servers
Well, that's not a GPS fix.
If you want a traceless position fix, use GPS Navstar / Glonass / Beidu / Galileo. Yes it takes longer from cold start, but that's the trade-off for privacy.
> Is it really surprising that people who have extremely precise time needs and a whole team devoted to solving them would notice issues that other people wouldn't
If GPS timing is bad, a lot of people will notice that their position on the map is incorrect, because that's the whole purpose of the GPS network.
Unless I'm missing something, couldn't you just fetch the GPS location and truncate the precision to 1/2/3 decimal points? There are subtler ways of doing this that mitigate
A: Oscillation of a user on the border between X,Y and X,Y+1
> if the car's local sensors deviate from the gps data significantly, that should throw up a red flag to the car and driver.
This happens too often for benign reasons (and GPS hacking too rare) for it to be useful. The GPS system in my Ford Focus jumps around wildly if I start the car in an enclosed space before it gets a good lock, and it can be thrown-off under bridges and around tall buildings as it doesn't have A-GPS (does any car have A-GPS?). The worst is when a poor signal is combined with road-snapping - I've had a lot of trouble with off-ramps on partially submerged urban highways, the I-5 in downtown Seattle, for example.
The article also places a big emphasis on people driving to the incorrect locations, hundreds of miles away from their intended destination. To me, this is a user error rather than a system issue. Every GPS system has the user confirm their destination address to keep this from happening.
GPS on phones aren't that accurate, especially downtown, but most applications will filter the data because of that. Ever use Google Maps for directions and make a turn different from what the app is telling you to do? Your car icon will continue down the "correct" path for 15-30 seconds before re-adjusting to the new route. This actually happens all the time, it's just more likely that your GPS is misreporting you as 20m east instead of you taking a different turn, so the app holds off on updating the display until it is more sure.
So it's a combination of the two factors. But most apps handle it muuuuch better than P:GO does.
Here's a link I was able to find on running apps specifically. Apps that deal with you being on foot will obviously have a harder time determining exactly where you are, as opposed to apps for driving where you're moving faster, in a straight line, and down a grid of streets.
http://radianttap.com/blog/2012/comparing-accuracy-of-the-gp...
reply