Model: MC-1-M (2U)
Doc. Ref. no. : - m05/om/101
Issue no. 14
Page 89 of 103
User’s Manual
14.
Holdover Mode
If GPS Master Clock Model MC-1-M is Power ON in Unlock conditions, the unit will provide time output
depending on the data of its internal RTC clock time which is available with battery backup (refer section
7.3). However, if the provided battery backup to RTC is discharged due to very long Power OFF period of
GPS Master Clock Model MC-1-M, at Power ON conditions in unlock conditions; all outputs of GPS
Master Clock Model MC-1-M device will have factory set time value and not the correct time. Once GPS
Master Clock Model MC-1-M device gets locked, all outputs will get proper time data.
GPS Master Clock Model MC-1-M device enter Holdover mode, when unit goes into Unlock condition
from Lock condition and thereafter provides time output depending on the internal clock crystal accuracy.
The accuracy of all time outputs (including 1PPS output) of unit will degrade depending on the duration
during which unit is in Holdover mode and also on the internal clock crystal frequency accuracy. If the
Unit again enter the Lock condition from Unlock condition, all the time outputs will become accurate as
per UTC time. Holdover mode conditions do not exist if GPS Master Clock Model MC-1-M unit gets power
reboot while unit was in Unlock condition. GPS Master Clock Model MC-1-M outputs will regain its
accuracy only when unit gets in lock condition once after Power ON.
