3.9 follow-up error
error which is caused by the delay between the existence of a value to be sensed and the availability of the corresponding signal or data stream at the output of the system. This error is e.g. the difference between the real heading of turning vessel and the available information at the output of the system.
The follow-up error disappears when the system is static.
3.10 settled
stable situation when any three readings taken at intervals of 30 min are within a band of O,7°, with the compass level and stationary.
NOTE The settling time is the elapsed time between the time of switch-on at the initial heading error and the third recording of the settle.
3.11 settle point heading
mean value of ten readings taken at 20 min intervals after the compass has settled as defined in 3.10.
3.12 settle point error
difference between the settle point heading as defined in 3.11 and the true heading.
3.13 error
difference between the observed value and the settle point heading as defined in 3.11.
3.14 latitude error
error to which some Gyro-compasses are subject. Its magnitude and sign depend upon the local latitude.
3.15 speed error
error to which Gyro-compasses are subject. Its magnitude and sign depend upon the speed, course and latitude of the ship.
3.16 master compass
main compass unit which supplies the heading information to the transmitting part or other navigational aids.
3.17 scorsby table
test machine which independently oscillates a platform about three axes. It is used to simulate the motion of a ship.
3.18 intercardinal motion
representing an integral motion of the ship. It is used for error test within motion in dynamic simulation test.
4 Performance requirements
4.1 Functionality
In this standard, the gyro-compass is specified as the function of THD.
