what portion of this signal is actual tilt of the spin axis.
modulated 4900-Hz carrier output of the accelerometer
The signal from the accelerometer control loop, which
before its transmission by cable to the compass control
consists of acceleration plus tilt signals, is integrated in
cabinet. By increasing the signal power level before
the speed-tilt computer loop to obtain a velocity plus tilt
transmission, crosstalk (or cross modulation) and
signal. The velocity component of this signal is removed
spurious disturbances that would degrade the inherent
by subtracting north-south speed, which leaves only
accelerometer signal-to-noise ratio are prevented. Two
such accelerometer preamplifiers are required per
system--for the meridian and slave gyros--and each
The accelerometer (fig. 4-42) is a pendulous mass,
contains its own power supply.
force feedback instrument that mounts directly to the
meridian gyro vertical ring. Its main components are the
proof mass, torque and backup plate, and pickoff, all
MK 19 MOD 3D GYROCOMPASS
mounted to a common support.
The proof mass is a curved aluminum plate
The Mk 19 Mod 3D gyrocompass system is
suspended by cross-spring pivots and is the element
identical to the Mk 19 Mod 3C system with the
against which the torque acts. Attached to an extension
exception that solid-state devices are used in the
of the proof mass is the iron pickoff core.
follow-up amplifiers, switching, and control
The torque is similar to the gyro torquers. It is a
2-phase induction type with the control field windings
in series, opposing, and the fixed field winding excited
MK 19 MOD 3E GYROCOMPASS
from the A transformer wired in a Scott "T"
arrangement. The torque is backed with a laminated iron
piece to improve the torque capability. The torque and
The Mk 19 Mod 3E gyrocompass system is
backup plate are encapsulated in plastic in such a
identical to the Mk 19 Mod 3D system with the
manner so as to enclose the proof mass.
exception that the compass has been modified to add an
optical cube used for alignment. This optical cube
The pickoff is a moving iron inductive-type
permits precise alignment of the compass during
transducer that detects relative motion between the
proof mass and the support. Excited with 4900 Hz to
In addition, the control cabinet has been modified
achieve frequency separation from the 400-Hz power
and a velocity interface unit has been added to permit
satellite interfacing with the compass.
sense proportional to displacement from a null or level
position. This signal is amplified and converted to 400
MK 19 MOD 3R AND
Hz to drive the torque, which restores the proof mass to
The tilt plus acceleration output is the 400-Hz
torque control field voltage. Because the accelerometer
The Mk 19 Mod 3R gyrocompass is a factory rebuilt
cannot distinguish between tilt and acceleration, the
Mk 19 Mod 3, rebuilt to Mod 3A specifications. The Mk
output contains both components. The acceleration
19 Mod 3RC gyrocompass is a factory rebuilt Mk 19
component is withdrawn in the speed-tilt computer loop,
Mod 3, rebuilt to Mod 3C specifications.
leaving only the tilt component.
The range of the instrument is
gram or a tilt of
23°35 minutes, and the scale factor is 75 volts per gram
or approximately 23 millivolts per minute of tilt. The
Watch-standing procedures for the Mk 19 Mod 3
pickoff excitation is 0.5 volts, 4900 Hz, and the torque
gyrocompass systems are basically the same as for the
Mk 23 Mod 0 and Mod C3 systems.
fixed field excitation is 100 volts, 400 Hz.