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Reference Number: AA-02331// Views: AA-02331// Created: 2024-07-18 16:35:16// Last Updated: 2024-08-27 14:51:52
General Article
Understanding GPS clock synchronization with RT-LAB model

The first step is to understand how the GPS clock can be connected to a simulation.


Let's start with the most simple one, where the GPS is just sending timestamps to the model:

The GPS clock is connected to the Oregano card placed at the simulator, sending a timestamp signal.

This Oregano card can communicate with the CPU of the simulator, sending this timestamp signal to the RT-LAB SM_ model using the Synchronization driver. It is important to highlight that the Synchronization driver should be configured by the IO Interface in RT-LAB, and will be linked to the model by using the OpInput blocks. This signals can be send to the SC_ subcircuit of your model and be displayed, allowing to compare the received timedtamp value with the one presented at the GPS. 

Note: some small time difference can exist between the timestamp values seen at the GPS and in the Host PC, due to the signal propagation process.

In this case there is no physical synchronization in time, since only the timestamp signal is been send. 

Another possible configuration is to connect the FPGA to the Oregano card. In this case the Oregano will convert the Timestamp signal into a pulse which will be send to the FPGA.



For the synchronization with the FPGA, an external connection between the Oregano, the Clock Adapter and the FPGA is required, as presente in the figure below:



The signal output from the oregano card shourd be connected to the External Clock Adapter which will be responsible by the conversion of the clock signal from the Oregano into an OPAL-RT model synchronization standard.


 In addition, for this case, the FPGA should be configured as Master with External clock, or the External Synchronization Source option should be checked in the IO Interface configuration:



In this configuration, it is possible to synchronize the operation of more than one equipment, for example, two or more simulators, since their FPGAs clocks are in sync with the same GPS reference.

To ensure that the synchronization is working fine, you will be able to load and run the model with no issues. If the synchronization is not working properly, the FPGA clock will not ne initializing, retuning you an error.


Note: For both cases, ensure that before launching your simulation, the GPS clock is connected to the Oregano and it is power on.

This is important because once the simulation is started, the Synchronization driver from RT-LAB will make the Oregano request for the signal. If the GPS is not available, the timestamp signals will not be received and, in case of FPGA synchronization, the FPGA will not be started.


Note: To know more about the synchronization driver in RT-LAB access our wiki page: Synchronization Driver RT-LAB