Calibration

We know that all of the devices have their own internal clocks, that they do not synchronize to NTP very often, and that their internal clocks drift. If required, for greater accuracy, you can calibrate the individual devices against NTP servers on the internet.

For the iPad, we have tried an app called Emerald Time (free). It will show the offset (in red) between the iPad's internal clock and the internet time. For the laptop, go to the website time.is and this will give you the offset between the laptop and the internet. The offset (difference in seconds) is the time between the true time and the device's internal clock; positive means the internal clock is behind. Add the offset to the device's time to get the true time.

The offset values can be entered into RDS on the start and finish line pages: click on (click to view details) in the top left of the start or finish line page. Enter the offset in the box for new values of NTP time offset, then press the Save/Refresh page button. RDS will use these offset values until you enter some more (since the devices clocks will continue to drift.