More than 20 parameters are logged through the ship’s automation system.
The timestamp for the logging has to be the same for each parameter in order to have the data logged at the same time.
The logging interval has also to be consistent or synchronised to the same level, e.g. 10 seconds
Over time there is some drift in time due to drift in the time interval for some of the parameters.
The drift in time interval is only a few seconds but over time this will lead to larger drift in timestamps.
The data format is an standards based format and stored in vessel database.
Each parameter has its own individual timestamp.
To neutralise drift and to achieve consistent logging intervals the following steps are taken:
– Consolidate identical start time for all parameters
– Identify timestamp interval by choosing one timestamp as default
– Run routine with synchronisation of parameters to default timestamp.
In cases where values are off sync, a linear interpolation is performed between data points.
The routine will ensure that all parameters now have the same timestamp and the same logging interval