Data processor unit System Clock
The unit maintains a realtime clock which tracks the current date and precise time. An internal 40 MHz oscillator, which is characterized and calibrated on each unit manufactured, advances the system clock at a precise rate. Optionally, the unit can use a GPS signal from an attached GPS receiver to regulate the internal oscillator, so that the system clock advances at the same rate as GPS time. This option can be enabled or disabled by the user under System > Preferences > GPS sample clock regulation. In this mode, the system date and time are still independent: the time is not set to GPS time, but the clock advances at the same rate as GPS time.
Setting the Date/Time
The system date and time can be set by the user from the System > Date and time page:
Each of these options are "one-shot" actions. After the date and time are set, the system clock advances independently using the internal oscillator, which may optionally be regulated by an attached GPS receiver as described above.
The current state of the oscillator regulation is displayed on the Setup > Hardware page. The unit will display Clock regulation: GPS if a GPS signal is currently being used to regulate the rate of the system clock, or Clock regulation: Internal if the internal oscillator is not being regulated.
Synchronization of Attached MX Modules
In all modes, attached MX devices are always synchronized to and regulated by, the parent unit's system clock. The status of this synchronization is displayed in the Setup > Hardware page. The MX module will display one of the following synchronization states: