Kongsberg EM Attitude 3000 datagram format

The Kongsberg EM Attitude 3000 is a proprietary datagram format created by Kongsberg Maritime for use with digital motion sensors. It holds roll, pitch, heave and heading information. The datagram contains a 10-byte message.

Format

Data description	Example	Format	Valid range
Sync byte 1 / Sensor status [1]	90h to Afh = sensor status	1U	00h, 90h to Afh
Sync byte 2	Always 90h	1U	144
Roll LSB [2]		1U
Roll MSB [2]		1U
Pitch LSB [2]		1U
Pitch MSB [2]		1U
Heave LSB [2]		1U
Heave MSB [2]		1U
Heading LSB [2]		1U
Heading MSB [2]		1U

Description

LSB = least significant byte

MSB = most significant byte.

Sync byte 1 / Sensor status

•

00h: This value is sync byte 1.

•

90h: This value indicates valid measurements with full accuracy.

•

Any value from 91h to 99h indicates valid data with reduced accuracy (decreasing accuracy with increasing number).

•

Any value from 9Ah to 9Fh indicates non-valid data but normal operation (for example configuration or calibration mode).

•

Any value from A0h to AFh indicates a sensor error status.

All data are in 2’s complement binary.

Resolution is 0.01 degrees for roll, pitch and heading, and 1 cm for heave.

•

Roll is positive with port side up with valid range ±179.99 degrees.

•

Pitch is positive with bow up with valid range ±179.99 degrees.

•

Heave is positive up with valid range ±9.99 m.

•

Heading is positive clockwise with valid range 0 to 359.99 degrees.

If a value is outside the valid range, it is assumed to be non-valid, and rejected.

Note

Heave is logged as positive downwards (the sign is changed) including roll and pitch induced lever arm translation to the transmit transducer.

You can define how roll is assumed to be measured, either with respect to the horizontal plane (the Hippy 120 or TSS convention), or to the plane tilted by the given pitch angle (i.e. as a rotation angle around the pitch tilted forward pointing x-axis).

The latter convention (called Tate-Bryant in the POS/MVdocumentation) is used inside the system in all data displays and in the logged data. A transformation is applied if the roll is given with respect to the horizontal.

Note

This format was originally designed for use with the early multibeam echo sounders manufactured by Kongsberg Maritime. In the original version of the format (Kongsberg EM Attitude 1000), the first synchronisation byte was always assumed to be zero. The sensor manufacturers were then requested to include sensor status in the format using the first synchronisation byte for this purpose.