MARINE DATA F069036, Руководство пользователя, Страница: 9 / 29

MD69BRX
9
5 PRINCIPLE OF OPERATION
The Repeater accepts serial heading data from a Gyro-Compass or Transmitting Magnetic
Compass in digital format using standard NMEA 0183 (IEC61162-1) True or Magnetic sentence.
The input is processed by electronic circuitry contained within the Repeater enclosure. Powered
from 18 V to 32 V dc derived from the ships supply, power consumption is low - typically less than
4 watts.
An embedded micro-controller processes the received heading information and in turn drives a
stepper motor connected to the dial. On application of power, the dial is rotated to align to a zero-
reference position controlled by an optical switch. Subsequently, on reception of valid data, the
dial is driven to display the received heading. When updated heading information is transmitted
to the Repeater, the dial will then follow this new heading.
Sophisticated firmware embedded in the micro-controller monitors the received data, user
controls and other control signals and provides control of dial illumination, and indicators.
Suppression circuitry and opto-isolation are used to provide over voltage and reverse polarity
protection as well as compliance to EMC and data transmission standards.