Section III. TECHNICAL PRINCIPLES OF OPERATION

TM 55-6605-263-14&P

1-11.

GENERAL.

a. The portable RMHS Reference Gyro Set is housed in a metal carrying case and consists of a Directional Gyro,

Power Inverter, Position Indicator, control panel, and required cables and connectors (fig. 1-1).

b. The RMHS Reference Gyro Set provides accurate heading information referenced to magnetic/true north to

calibrate existing on-board watercraft compass systems.

1-12.

TECHNICAL PRINCIPLES OF MAJOR COMPONENTS.

a. Principles of Operation. The Directional Gyro is a case-level, free-running Gyro in which the Gyro assembly

(inner gimbal) maintains a level, or upright position within the gimbalring (outer gimbal). Changes in watercraft heading

are reflected by corresponding changes in the position of the inner gimbal with respect to the outer gimbal. These

changes in relationship between the inner and the outer gimbals produce accurate and stabilized reference output signals

which are fed to the angle position indicator. The Gyro input power requirements are 115 Vac, 400 Hz from the static

power inverter.

b. The static power Inverter converts a nominal +27.5 Vdc external input to a regulated 115 Vac, 400 Hz 20 Hz,

single-phase output. A pulse width modulation technique is used and provides a sinusodial output waveform rated at 150

VA continuous. This regulated output voltage is fed to the Directional Gyro and Angle Position Indicator.

c. The Angle Position Indicator uses a type II servo lock-loop converter which receives the Gyro's reference signal

and converts it into an analog signal. The analog signal is reflected on the Light Emitting Diodes (LED), lazy eight

display panel Indicating heading in degrees and minutes.

1-13. FUNCTIONING OF EQUIPMENT SYSTEM. The following functional description of the RMHS Reference Gyro

Set is shown in block diagram figure 1-6. When control panel ON-OFF-POLARITY switch is in the ON position, 28 Vdc is

applied to the power inverter. The output of the power inverter, 115 Vac 400 Hz, is then fed to the Gyro and Angle

Position Indicator units. When the Gyro's latitude switch is in the north or south hemisphere position, a latitude course

correction is made to the Gyro. When the latitude knob (potentiometer) is positioned to actual latitude of the watercraft a

very accurate correction is made to the Gyro. The resulting stabilized reference signal from the Gyro, indicating the

actual

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