| Support > Library > FAQs and Troubleshooting > One_hour_error_after_DST_change
|
|
FAQ's and Troubleshooting
Q13. Why is my Ethernet time server is off by one hour after a DST change?
- A.
Check for the following conditions:
* The source of time is a Spectracom NetClock/2 master clock,
* Model 8182 The NetClock/2 is configured for local time,
* The NetClock/2 output to the Ethernet time server is format 0
Solution:
* Verify the NetClock/2 is running firmware previous to v1.17,
* Update the NetClock/2 to firmware v1.17 if necessary
Cause: The Spectracom NetClock/2 employs the WWVB time synchronization signal (predecessor to the current GPS-based NetClock designs). Due to the unique method in which WWVB adjusts for Daylight Saving Time (DST) these older NetClock/2’s (Beige or black enclosures), if not equipped with firmware v1.17, will cause the Ethernet Time Servers(s), (ie. Models 8188 and 9188) that are connected to them to provide incorrect timing data. The symptom is a one hour error in the time outputs from these Time Servers during a DST rollover which may continue for several hours after 2AM local time.
Note: All Spectracom Models 8188’s and 9188’s that are synchronized to a Spectracom GPS-based clock, ie. Models 8183 and 9183 will not experience this time error.
The cause of this one hour error is due to the fact that NetClock/2 firmware versions prior to v1.17 use the DST transition character (a character that indicates whether we are currently in DST or Standard time or if transitioning from one to the other) in the RS-485 output data stream that synchronizes devices such as Ethernet time servers. When the NetClock/2 is configured for local time, the Ethernet time server converts it back to UTC and will use the DST transition character in the calculation. The time error results since the WWVB signal does not change the transition character at 2AM local since it is a nationwide broadcast and does not descriminate time zones. It waits at least until the local time in every time zone in North America is 2AM. The problem can continue longer if reception-related issues is effecting WWVB signal reception.
For further information on this issue, checking NetClock/2 firmware version and how to upgrade the firmware, see NetClock/2 and model 8188/9188 Ethernet time servers (pdf)
- « Go Back to FAQ's
<
|
|
|
|
|
|
|
|
|
|
|
|
|