4 ms·
Will it get a lock any quicker? It would be nice if accuracy could be traded off for time, so that instead of getting a more accurate lock, we're getting a the
by zmmmmm 16y ago
Will it get a lock any quicker?
It would be nice if accuracy could be traded off for time, so that instead of getting a more accurate lock, we're getting a the old accuracy but quicker.
For me the biggest limitation of GPS is that it can take > 1 min to get a lock on a regular basis. I know this is hardware and software dependent ... but it's still common for it to be at least 20 seconds even on the best hardware, I think. Apart from making apps that rely on GPS awkward ("please wait an indeterminate amount of time while we find your location") it also means much greater power use because the GPS has to be active for longer (GPS seems to be something that noticeably uses a lot of power in my Nexus One).
- uuilly 16y agoWhile too advanced for the phone at this stage, there is something called "direct inertial aiding" that solves this problem. Basically it uses the gyro to estimate the position during a gps outage and then it can tell the GPS where to look in the sky for satellites. As it is, the gps has to scan the entire sky and it assumes nothing about its position. Even if you just passed under a bridge and only had a monetary outage. Direct Inertial Aiding makes pick-back-up times very small.
- georgecmu 16y agoit can tell the GPS where to look in the sky for satellites. As it is, the gps has to scan the entire sky Your entire mental model of how GPS works is wrong.
- guygurari 16y agoI used to have this problem on older devices, but the GPS on my iPhone 4 consistently gets a lock almost instantaneously. I guess YMMV.
- enf 16y agoA lot of the delay in getting an initial GPS fix is downloading the almanac for the satellites at the very slow GPS bit rate. The iPhone 4 probably periodically retrieves the almanac over GSM instead, allowing much faster location fixes. (Several models of Android phones do this.)
- aw3c2 16y agoThat's AGPS. Very straight-forward and useful technology: http://en.wikipedia.org/wiki/Assisted_GPS http://en.wikipedia.org/wiki/Assisted_GPS