Filter States

The filter status field in the Status (0x82,0x10) message reports the Estimation Filter's current state. The Estimation Filter has three states, or modes.

Column one of the table below shows the three Estimation Filter states. The second column shows the corresponding value reported for each state in the filter status field in the Status (0x82,0x10) message. The third column shows the initial conditions that must be provided to the Estimation Filter to achieve each state.

Below the table, each state is described in greater detail.

 

Filter Mode	Filter State Value	Initial Conditions Required	Notes
Initialization	1	none	none
Vertical Gyro	2	none	heading relative to initial heading
AHRS	3	absolute heading measurement	heading relative to true or magnetic north (absolute heading)

 

Initialization

In this mode, initial conditions are incomplete or invalid.

 

Vertical Gyro

In this mode, the filter reports valid gyro stabilized pitch and roll estimates and heading estimates relative to the initial heading provided by the user. If an initial heading is not provided by the user, the filter will provide relative heading estimates referenced to its orientation at initialization time.

See Filter Initialization for details on entering an initial heading.

In this mode, only the 3DM-CV7's internal inertial measurements are incorporated by the Estimation Filter.

 

AHRS

This mode is similar to the vertical gyro mode, except a valid absolute heading reference has been provided from either the user or the magnetometer. See Filter Aiding Measurements for more details on heading measurement sources.

If the 3DM-CV7 does not receive a heading measurement for 5 seconds, it will revert back to vertical gyro mode. This is not an issue when using the internal magnetometer for a heading measurement.