Re:One second per second is harder than it sounds
by easytiger on Tuesday July 22, 2014 @04:02AM
(#8067811)
For phones to achieve that the GPS would have to be turned on & synced near constantly. Also the accuracy goes down with mobile devices and new strategies have to be applied given the change in altitude and greater temperature flux. It also depends on the phone's internall oscillator & the gps recv unit used.
Mobile phones use CDMA stuff to sync their clocks, not GPS
Re:One second per second is harder than it sounds
by pjc50 on Tuesday July 22, 2014 @04:56AM
(#8067926)
GSM phones are supposed to be able to pick up "NITZ" (network information and time zone") messages, but these aren't reliably sent by most networks. In practice, smartphones get it over NTP like everyone else and dumbphones have user-set time that may, if you're lucky, be synced by counting the base station's time slot intervals.
Re:One second per second is harder than it sounds
by easytiger on Tuesday July 22, 2014 @05:50AM
(#8068092)
Yes modern smartphones often hardcode ntp servers and prob do ineffective hard resetting. Would be good to know more how they do it.
Re:One second per second is harder than it sounds
by enf on Tuesday July 22, 2014 @11:52AM
(#8069607)
Things have changed a bit since the last time I had anything to with it, but you can read the Android source code: https://github.com/android/platform_frameworks_base/blob/mas...
NITZ is terrible. You only get one-second accuracy, a GMT offset, and a DST flag, and they can all be wrong at the whim of someone at the phone company.
GPS time is theoretically accurate to about 14 nanoseconds. However, most receivers lose accuracy in the interpretation of the signals and are only accurate to 100 nanoseconds.