Measurements of iPhone clock accuracy.

This is one hour of data starting 57123.008659 / 2015-04-11 00:12:28 UTC / Fri Apr 10 17:12:28 2015 PDT

Raw data: iphone-tick-log4317-1s.txt
30 second filtered data: iphone-tick-log4317-30s.txt
Units are second past UTC. That is, the iPhone is late by about 85 ms.

10 MHz and 1PPS reference was Trimble Thunderbolt GPSDO.
Acoustic sensor and amplifier from http://www.bmumford.com
Timing performed by my picPET (precise event timer) from http://leapsecond.com/pic/