Table 4-3.--Data Display Parameters

distribution to the ship's equipment and is sent to the

outputs. Automatic calibration requires 24 hours to

A/D multiplexer for use by the processor.

complete but will continue as long as the mode switch

is in this position.

The digital display indicator provides for local

display of the quantities shown in table 4-3. Data for

Setting the MODE switch to AUTO CAL at anytime

display is selected by the DSPL SEL switch.

after completion of the leveling sequence places the

equipment in the AUTO CAL mode. This mode starts

Nav Mode

an automatic recalibration sequence to determine new

gyro biases, accelerometer biases, and latitude

The NAV mode, the primary operating mode, is

corrections. These new values are automatically

mechanized the same as the AUTO CAL mode. In the

averaged with old values to accomplish equipment

NAV mode, the heading is not slewed and the alpha

recalibration.

angle is held at zero; thus, the equipment becomes a

north-pointing gyrocompass.

All gyro functions and outputs are maintained in the

AUTO CAL mode. The outputs from the IMU resolvers,

The NAV mode is the normal mode of operation and

representing pitch and roll angles, are applied directly

is used between latitudes 85 north or south. If the NAV

to the synchro signal amplifier. The synchro signal

mode is initially selected as the mode of operation, the

amplifier amplifies the resolver input information and

alignment sequence must be completed before the

transmits dual-speed synchro information to the ship's

gyrocompass is capable of providing full accuracy

equipment. Roll and pitch angle information is also sent

outputs. This sequence takes approximately 4 hours.

The alignment sequence is completed when the MODE

to the A/D multiplexer.

ALIGN indicator goes off and the MODE NAV

In the AUTO CAL mode, heading is continuously

indicator comes on.

slewed, completing 360 every 24 hours. The IMU

heading signals are sent to the true heading converters.

DG Mode

Also applied to the true heading converters is the alpha

angle. In AUTO CAL it is set to a value representing 15

The DG mode is used at latitudes above 85 north

per hour. These two signals are combined in the true

or south. When the gyrocompass is operating in the DG

heading converter to develop true heading information.

mode, the stable element is dampened by velocity

The output of the true heading converter is sent to the

signals and allowed to wander in azimuth. Earth rate

correction is made by torquing the stable element in

synchro signal amplifier for amplification and

Table 4-3.--Data Display Parameters

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