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5 Recording the current situation 
The recording of the current situation is divided into three sub-processes: state identification, observa 
tion of the environment, and object recording. 
From the sensor data available, state identification determines a description of the current state which is 
valid system-wide. This description comprises variables for describing the current position, the move 
ment, water depth, engine data and rudder angle. The requirements on the input information “sensor 
data” relate primarily to additional data on the validity, topicality and accuracy of the particular datum. 
These data enable assessment and selection of the state variables used system-wide. 
Within the framework of observation of the environment, a description of the current environment situa 
tion or that expected in the near future is derived by evaluating weather data and sea data. Since it is 
scarcely feasible to automate a large number of functions here for on-board operation (e.g. evaluation of 
weather charts, sea observation), this process can only be integrated in an INS to a limited extent. Fun 
damental requirements refer here to the validity and quality of the data used as a basis (weather charts, 
sensor technology). 
Object observation serves the purpose of identifying objects (type, position, movement) on the basis of 
data recorded by sensors (radar/ARPA, transponder/AIS), visual observation or external information 
(VTS). Requirements derive from standards and harmonisation between the components and informa 
tion involved in object observation. These include in particular: 
• Systems for object identification (radar/ARPA, transponder/AIS) 
• State variables (conversion of relative object movements into absolute movements, determination of 
characteristic variables such as CPA and TCPA). 
• Display equipment, e.g. representation of ARPA objects in ECDIS.