Compensation Signals - Cont'd -141200143

the shaft of the linear synchro to provide a visual

acceleration signal being fed to the meridian control

indication of own ship's speed.

integrator cutout, which operates a relay, cutting out the

tilt signal during excessive accelerations.

The own ship's speed signal is applied to the input

For the tilt signal outputs from the electrolytic

stage of a type 1 computer amplifier in the speed

component computer. The speed computer (fig. 4-28)

bubble level to average out to zero, the compass must

contains two type 1 computer amplifiers, a speed

be in perfect balance, and all compensating signals

resolver and dial (B4), a synchro control transformer

computed exactly. The constant torque compensation

(B5), and a motor tachometer (B6).

system will then compensate, within limits for errors in

computation of other compensating signals.

The motor-tachometer (B6) is a 400-Hz servomotor

tachometer generator built into the same housing. The

The constant torque compensation system for the

motor is a 2-phase, 4-pole, induction motor with a fixed

slave gyro is identical to the meridian gyro system.

field and a control field. The tachometer generator

section consists of a 2-phase, 2-pole stator and a copper

Operation of Compensation Circuits

shell rotor. One stator field (F1) is excited from the

The own ship's speed repeater operates on 60-Hz

115-volt, 400-Hz supply. The other stator field (F2) is

data obtained from the ship's underwater log transmitter.

not excited as long as the rotor is stationary (the axes of

The output of the repeater, however, is 400-Hz data. The

the two stator windings are 90 apart). When the shaft

repeater contains a 60-Hz servomotor (B1), a 60-Hz

of the rotor is turned, a voltage is induced in the rotor

synchro control transformer (B2), a 400-Hz linear

and rotor current flow is proportional to rotor speed.

synchro and dial (B3), and a type 2 computer amplifier

This rotor current produces a magnetomotive force

(A1). (See figs. 4-27 and 4-28.)

proportional to rotor current. This magnetomotive force

is combined with the magnetomotive force of the refer-

The linear synchro is an induction device like other

ence winding to produce a resultant field, the axis of

synchros, but differs from other types in that it has one

which is displaced in the direction of rotation of the rotor

input rotor winding and one center-tapped output stator

cup. The angle between the resultant field axis and the

winding that produces an output voltage that is a linear

axis of the output winding varies with the speed. Hence,

function of its rotor position. The rotor winding is

the coupling between the two stator windings varies

excited from the 400-Hz supply. When the rotor is in

with speed. Thus, the output voltage varies with the

such a position that the axes of the two windings are

speed. Its frequency is 400 Hz, the same as that of the

separated by 90 electrical degrees, no voltage is induced

reference field, and the phase of the output voltage is

in the output stator winding. If the rotor is displaced in

dependent upon the direction of rotation of the rotor cup.

one direction from this zero voltage position, a voltage

is induced in the output winding that is proportional to

The own ship's speed signal is amplified and fed to

the amount of rotor displacement. If the rotor is

the rotor winding of the speed resolver (B4). Heading

displaced in the opposite direction, a voltage of opposite

data from the master compass is applied to the input of

phase is induced in the output winding that is also

the control transformer (B5), and the output of the

proportional to the amount of rotor displacement.

control transformer (B5) in series with a damping

voltage obtained from the generator section of the

The 60-Hz servomotor is a 2-phase, 2-pole,

motor-tachometer (B6) is fed to the input of the second

induction motor, with a fixed field excited from the

type 1 computer amplifier. The damping signal voltage

60-Hz power line, and a control field connected to the

from the motor-tachometer is used to stabilize the com-

type 2 computer amplifier output.

puter servoloop and to introduce a small time lag in the

computer. his time lag is required since the direction

The input to the repeater is the own ship's speed

of motion of the ship's center of gravity differs from the

from the underwater log to the control transformer (B2)

ship's heading for a short interval after starting a course

(fig. 4-28). The output signal voltage from the control

change. In other words, when rudder is first applied to

transformer, representing ship's speed, is fed to the input

turn the ship, the ship slides sidewise to some extent so

of the type 2 computer amplifier. The servomotor (B1)

that the original course is maintained for a short interval

drives the control transformer rotor to its null position,

even though the ship's heading has changed.

and at the same time positions the linear synchro rotor

The output of the second type 1 computer amplifier

(B3) to a position corresponding to the ship's speed. The

linear synchro output, then, is a 400-Hz voltage

excites the control field of the motor section of the

proportional to own ship's speed. A dial is attached to

motor-tachometer (B6), which drives the tachometer

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