Filter States

The filter status field in the Status (0x82,0x10) message reports the Navigation Filter's current state. The Navigation Filter has three states, or modes. The state that the Navigation Filter operates in is determined by the initial conditions provided to the Navigation Filter through the Initialization Configuration (0x0D,0x52) command. See Filter Initialization for details.

Column one of the table below shows the four three Navigation 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 Navigation 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)
Full Navigation	4	absolute heading measurement, initial position, initial velocity	heading relative to true or magnetic north (absolute heading), position, velocity

 

Initialization

In this mode, initial conditions are incomplete or invalid, or else the sensor is waiting for required input from the user.

 

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-GQ7's internal inertial measurements are incorporated by the Navigation Filter. However, if independent position and velocity estimates are available, either from the internal GNSS receivers or provided by the user, the Navigation Filter will pass those values through.

 

AHRS

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

If the 3DM-GQ7 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.

 

Full Navigation

Filter reports valid position, velocity, pitch, roll, and heading estimates. To enter this mode, the Navigation Filter requires valid initial position, velocity, and heading estimates. These estimates can be retrieved from external aiding measurements for position, velocity, and heading, or internal magnetometer heading,internal measurements or provided by the user. See Filter Initialization.