Novatech Kronos 2 Series - Clock States; Figure 9: Clock States

Kronos Series 3
19
3.3 Clock States
After first lock has been achieved (see section Power Up Sequence), the clock will be in one of four states
(Figure 9):
Figure 9: Clock states
Clock State
Description
Locked
Enough satellites are being tracked. The internal oscillator is locked in time, frequency,
and phase to the atomic clocks on board the satellites. Calibration factors for the internal
oscillator are derived and kept up to date.
Holdover
Not enough satellites can be tracked to compute a solution. Time, frequency, and phase
are derived from the internal oscillator. An error estimate is constantly updated and
compared against two user-defined thresholds.
Low quality
Time, frequency, and phase are still derived from the internal oscillator. However, the
error estimate is greater than the first user-defined threshold value. A level 1 alarm is
raised to signal to the user that the first error limit has been exceeded. The default value
for this threshold is 500μs. See section GNSS Settings (Online) or Out-of-bound Limits
(Offline) for information about how to change this to a different value.