Principle Of Operation; Application - MARINE DATA MD52A User Manual

5 PRINCIPLE OF OPERATION

The MD52A requires to be mounted on or under a host magnetic compass in close
proximity to the compass card. The MD52A outputs a 3 phase positional signal by
sensing the orientation of the host compass card. In this way, the MD52A acts as a
Compass Sensor or a Magnetic Pickoff Coil.

6 APPLICATION

The MD52A is a Transmitting Heading Device (THD). It transmits a 3 phase positional
signal, this data is converted to a NMEA signal by the MARINE DATA MD97-52
Compass Sensor Interface. The data can be further processed by a MARINE DATA
MD93 Variation and Deviation Corrector or a MARINE DATA MD86HCU Heading
Comparator Unit to retransmit corrected magnetic Heading data in standard NMEA
0183 (IEC61162-1) digital format.
In this way, the MD52A is the sensing element in a Tramsmitting Magnetic Compass
(TMC) System.
The following NMEA 0183 sentences may be used to display Heading:
Heading
Priority
Type
1 HDG
2 HDM
( $--HDG, x.x, x.x, a, x.x, a*hh<CR><LF> )
Heading True (from Magnetic) (Heading Data corrected for the Earth's
Magnetic Variation and the vessel's Deviation)
( $--HDG, x.x, x.x, a, , a*hh<CR><LF> )
Heading Magnetic (Heading Data not corrected for the Earth's
Magnetic Variation and the vessel's Deviation)
( $--HDM, x.x, M*hh<CR><LF> )
Heading Magnetic (Heading Data not corrected for the Earth's
Magnetic Variation or the vessel's Deviation)
Sentence and Description
MD52A
9