Furuno SC-110 manual AP-5, GNS - GNNS fix data, HDM- Heading - magnetic, HDT - Heading - true

APPENDIX

GNS - GNNS fix data

$--GNS,hhmmss.ss,llll.lll,a,yyyyy.yyy,a,c					--	c,xx,x.x,x.x,x.x,x.x,x.x*hh<CR><LF>
												+--- 11
											+------	10
										+	----------	9
									+	--------------		8
								+	------------------			7
							+	----------------------				6
						+	-------------------------					5
					+------------------------------							4
			+-------	+---------------------------------								3
	+---	+	---------------------------------------------								2
+	-------------------------------------------------------------										1

1.UTC of position

2.Latitude, N/S

3.Longitude, E/W

4.Mode indicator

5.Total number of satllite in use,00-99

6.HDOP

7.Antenna altitude, metres, re:mean-sea-level(geoid)

8.Geoidal separation

9.Age of differential data

10.Differential reference station ID

11.Checksum

HDM- Heading – magnetic

This sentence is not used in the current version of NMEA and IEC 61162. Some boaters may want the GPS compass to indicate the magnetic heading when the boat is only fitted with a magnetic compass. HDG is calculated by adding a geomagnetic variation to HDT.

$--HDM, x.x, M *hh<CR><LF>

Heading, degrees magnetic

HDT - Heading - true

True heading in degrees obtained by processing RF cycle in the GPS carrier frequency. $--HDT, x.x, T*hh<CR><LF>

Heading, degrees true

THS – True heading and status

Note: This sentence replaces the deprecated sentence HDT.

Actual vessel heading in degrees true produced by any device or system producing true heading. This sentence includes a “mode indicator” field providing critical safety related information about the heading data, and replaces the deprecated HDT sentence.

AP-5