(1) magnetometer-controlled equipment and (2)
for the change in induced magnetization caused by a
gyro-controlled equipment.
change in ship's heading.
Magnetometer Control
Emergency Manual Control
Signals to control the induced field currents are
All AUTODEG control equipment is equipped with
obtained from a three-axis magnetometer. The
emergency manual control for use if the automatic
magnetometer measures the components of the earth's
controls become inoperative. This equipment is
field along the axis of the ship and automatically adjusts
manually operated by the operator. The operator sets
the coil currents in a manner that will compensate for
currents to values obtained from the ship's degaussing
changes in induced magnetization caused by the ship's
folder for the various magnetic latitudes and adjusts the
roll and pitch and by changes in the ship's heading and
eight-course heading switch as the ship's heading varies.
geographical location. You can obtain the perm field
current by biasing the magnetometer output with a perm
bias component or by providing a P coil with a separate
regulated current source or a combination of both
TYPES OF AUTOMATIC DEGAUSSING
methods.
SYSTEMS
Magnetometer control is used on nonmagnetic
Look at table 10-2, which contains brief
minesweepers because roll and pitch compensation and
descriptions of the different types of AUTODEG. For
smooth or stepless zone control (magnetic latitude
detailed descriptions, you should refer to the applicable
variations) are needed for these ships. It is also used on
technical manuals. The first three types of equipment
minesweepers because the magnetometer can be readily
shown in the table are the only types being installed on
located so it measures the earth's field rather than a
new ships.
combination of earth's field, ship's field, and other
interference fields.
MDG DEGAUSSING EQUIPMENT
Magnetometer control is used on some steel-hulled
ships with aluminum superstructures, where the effect
of the ship's field on the magnetometer can be cancelled
MDG degaussing equipment is installed on
by compensation techniques. Magnetometer control is
nonmagnetic minesweepers. This equipment consists
used on these ships to eliminate operator inputs (H, Z,
of a fluxgate-type triaxial magnetometer probe installed
and magnetic variation) required with gyro-controlled
on the ship's mast and a control unit containing all
equipment.
control and power circuits installed in the combat
information center (CIC) or the pilothouse (fig. 10-12).
Gyro Control
The magnetometer probe is located and aligned so it
measures the local earth's magnetic field components
Signals to control the induced field currents are
along each of the ship's three axes. These field
obtained from the ship's gyrocompass and gyro
components are biased and amplified by the degaussing
stabilizer systems. These signals are modified by
equipment to produce required degaussing coil currents
operator inputs for magnetic latitude and heading
(fig. 10-13). The probe's location must be free of
(operator sets H, Z, and magnetic variation controls).
interference produced by the ship's magnetic field,
They are processed by an analog computer to provide
degaussing coils, and other installed equipment. The
induced field currents proportional to the calculated
equipment is unique in that 90 separate power amplifiers
values of the earth's magnetic field component along the
are available to supply the ship's degaussing loops.
ship's axis.
You can obtain the perm field current by biasing
Magnetometer-controlled AUTODEG
computer output or with a separate P coil or a
Equipment Operation
combination of both methods. Gyro control is presently
used on ships that do not require roll and pitch
Two modes of operation are used for magnetometer
compensation. On these ships, the control signal is
controlled AUTODEG equipment--automatic and
obtained from the ship's gyrocompass, and the coil
currents are adjusted automatically to compensate only
manual.
10-9
