Synchronizer

The Synchronizer module is responsible for collecting the data of the latest epoch from all (selected) reference stations and sending it to the Processing Engines as one epoch of data. Synchronizers must, therefore, be started before adding a processing engine to Trimble 4D Control Server. Depending on your Trimble 4D Control Server edition, you may run different types of processing engines below one Synchronizer module, such as RTX Engine for station positions derived from RTK solutions which are based on highly accurate clock and orbit messages provided by the Trimble global tracking network or RTK Engine for station positions derived from receiver observations belonging to your network.

The Synchronizer module collects and passes on data from GNSS Receiver modules. It automatically recognizes when GNSS Receiver modules are removed and adapts itself accordingly. It also recognizes automatically, if GNSS Receiver modules are added, but does not add them to the selected stations.

Adding the module

The Synchronizer module is available from the Tree view item Trimble 4D Control Server. Trimble 4D Control Server accepts several Synchronizer modules. For example, you can split up the system in several sub-networks using different Synchronizers.

When the module is being added, the Synchronizer Properties dialog appears. It lets you define and select Synchronizer module configurations. Each configuration holds information on number and the IDs of selected stations. You may remove a configuration from here, if you do not need it anymore. You may change the settings of the selected Synchronizer configuration at any time.

Module status

The Synchronizer module displays several module-view pages.

Applying observation corrections

If available, the Synchronizer module applies observation corrections to the data collected from the GNSS Receiver modules. For the types of observation corrections see the following table.

Observation correction type	Reason	Corrections are derived from...
Solid Earth tides	"Deformations of the solid Earth due to the body tides arising from the direct effect of the external tide generating potential" (mainly, the Moon). (See: IERS CONVENTIONS)	An internal model.
Ocean tidal loadings	Deformations of the solid Earth due to the "temporal variation of the ocean mass distribution and the associated load on the crust". (See: IERS CONVENTIONS)	A file: ocean_tide_loading_grid.txt.
Pole tides	The oscillation of the Earth's rotational axis around its nominal direction results in an additional centrifugal force which displaces the surface. (See: IERS CONVENTIONS)	A file: earth_orientation_params.txt.
Carrier phase wind-up	Bias introduced into carrier-phase measurements depending on the relative orientation of the GNSS receiver antenna with respect to the satellite antenna (which changes as it orbits about the Earth because the satellite always needs to be exposed to the sunlight) as well as on the direction of the line of sight between them. (See: J.T. Wu et al; “Effects of antenna orientation on GPS carrier phase”; Manuscripta Geodaetica, 19, 1993, pp. 91-98).	An internal model.
Satellite phase center	Offset of the antenna phase center of a satellite to its center of mass and phase center variations. The satellite orbit products are often the orbits of their centers of mass. The broadcast orbits are orbits of the phase center itself.	ANTEX files.

During installation, the default values for these corrections have been set. The Trimble web server makes the most current updates for these corrections available for downloading. You should set up the System Properties dialog for the automatic update of the correction files when new versions are available.

Exporting station information

For exporting the station information of all stations selected for a Synchronizer module, right-click the module in the Tree to open its shortcut menu and select one of the export options.

The Export IGS Site Log Files command opens a standard Browse For Folder dialog. Use it to select the folder where the .log files are written to. A message appears after the files have been written to the selected folder.
The Export Google Earth KML File command starts the automatic export of all station data into a KML data file. The Specify the KML File dialog appears that lets you specify the name and location of the exported Google Earth KML file.
The Export CSV File command starts the automatic export of all station data into a Comma Separated Values data file. The Export Station Information as CSV dialog appears that lets you specify the name and location of the export file.

Using one of the export commands, the station information of the following stations will be exported in one step:

Station data of all GNSS Receiver modules selected for the selected Synchronizer module(s), which are currently running under any Device Manager module.

Alarming

With alarming activated, the Synchronizer module triggers alarms, if one of the following happens:

A receiver was excluded because it was delayed for more than the period specified in the Synchronizer properties (Alarm condition Exclude delayed receiver occurs).
An formerly excluded receiver is included, because it is healthy since more than the period specified in the Synchronizer properties (Alarm condition Exclude delayed receiver disappears).

Tip - An active Exclude delayed receiver alarm stays active, even if the Synchronizer module is moved to a different Container. If you unload a Synchronizer module, however, all active alarms will be disabled.

Logging into the database

All actions of the Synchronizer module are logged into the central database. The database contains the following tables referring to the Synchronizer system:

Table name	Contents	More information
StationDelay_Synchronizer_<config name>	Delay of observation data per station.	One entry per minute and station.
SynchronizerDelay_<config name>	Delay of synchronized epochs.	One entry per minute.
SynchronizerStationCount_<config name> *	Change of number of expected, synchronized, or delayed stations.	One record per any change of the record contents.

*By default, the data of these tables is reduced depending on settings of the TableLifeTime table.