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Atomic Clock vs Local Computer Time Base

Last Updated: Jul 26, 2016 05:55PM CDT

Time Base Defined

During initialization, devices are given a "Start Time". That is, the time at which the device should start collecting data. The Start Time concept requires that the device itself be given a time base.  When a device is initialized, ActiLife sends the current time to the device to serve as this time base. The device contains a very accurate crystal oscillator which begins incrementing the time base. This acts as the device's on-board clock until the device is reinitialized. Although there is some clock drift expected, it is minimal due to the high accuracy of the on-board crystal oscillator.

Atomic vs Local

Beginning with ActiLife 6.5.0, the initialization screen offers users the ability to select between a time base from the local computer or an atomic clock. The choice can be toggled by clicking on the hyperlink to the right of the "Device Time" option as shown below:

time.png

When local time is selected, the devices will be programmed with the computers local time as the time base. When the atomic time is selected, ActiLife attempts to capture the time base from the United States National Institute of Standards and Technology (NIST) time servers list located at http://tf.nist.gov/tf-cgi/servers.cgi. ActiLife first attempts to make connection with one of five random NIST servers from the list given in the hyperlink. If a time is available, the computer's local time-zone offset setting is used to set the correct hour. The minutes and seconds settings captured directly from the NIST server are used to complete the time base. If none of the five random servers are available, the time base will default to the local time.

This feature is helpful when synchronizing data collection across multiple sites.

If you need any further assistance, please visit our support portal at https://help.theactigraph.com/home. From there, you can view many helpful FAQ's and Troubleshooting Articles; log in to check any existing Support Requests; or create a new Support Ticket if you are unable to find a solution. You can also email us at support@theactigraph.com or give us a call at (877) 497-6996, Monday through Friday, 8 am to 5 pm CST.

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