Core concepts

​A data value column represents a single value measurement. Typical data value columns are Distance, Temperature and Wind Speed.

A data type is a set of data value columns that represents readings that are normally measured together. For example, the data type Terrestrial Displacement has readings for Delta Northing (dN), Delta Easting (dE) and Delta Height (dH), and so on. Many data types only have a single data value column, for example the data type Temperature has only the data value column Temperature, because there is only one reading value for temperature.

Data types with positional or displacement data value columns are called positional data types.

The sensor type of a sensor determines the data types associated with the particular sensor. For example a Water Level Gauge has the data types Temperature and Water Depth, while an inclinometer has the data types Temperature and Tilt.

Although the sensor type of a sensor determines all the possible data types associated with the sensor, in Trimble 4D Control you can choose a combination of the available data types to be associated with a particular sensor. For example you can choose to associate only the data type Water Depth with a particular sensor of sensor type Water Level Gauge.

A sensor group is a user‑defined collection of sensors. Each sensor group is configured with a data type that is common amongst the sensors belonging to that group. A sensor may belong to more than one sensor group.

A sensor group based on a positional data type allows you to create a Group Sensor linked to that sensor group. Trimble 4D Control Server will automatically calculate representative observations for the group sensor from the sensors in the particular sensor group.

Viewing or analyzing sensor observations over a long time period may involve an overwhelming amount of data points. Trimble 4D Control provides a solution to this by automatically storing the observations as the raw readings (or every epoch) together with summarized data sets.

A summarized data set could be calculated as a value per second, a value per minute, a value per hour or a value per day. A summarized data set effectively allows a reduced view of observations.

The most common reduction method is to take a moving average of the raw readings. However the reduction method for velocities are different – in this case the last calculated velocity value within the time period is used as the representative or summarized value.

Trimble 4D Control automatically calculates and stores the velocity of observations of positional data types. The summarized data sets of velocities are also calculated and stored.

A typical velocity unit of measure is for example meters per day. The velocity values are calculated over time intervals of 3 hours or 1 day. It is important to note that the unit in which you express velocities are independent from the time interval over which the velocity was calculated.

An absolute measurement is the raw reading measured on a sensor.

A reference measurement is a previous absolute measurement made at some previous point in time (called the reference date).

A relative measurement is the difference between the absolute measurement and the reference measurement.

Relative measurements are useful to monitor structural changes with respect to some fixed measurement in the past, or a moving reference date at a fixed time period in the past (for example the absolute measurement 7 days ago).

Sensors in Trimble 4D Control can receive observations from an automatic readings feed or you can manually add readings to a sensor. The Data Source Mode is only selectable on creation of a sensor and determines whether a sensor is an Automatic Sensor or a Manual Sensor.