Argus Radar - SERIAL INTERFACE SPECIFICATIONS
988-10187-004 2.20
DTM - Datum reference
Local geodetic datum and datum offsets from a reference datum. This sentence is used to
define the datum to which a position location, and geographic locations in subsequent
sentences, are referenced. Latitude, longitude and altitude offsets from the reference datum,
and the selection of the reference datum, are also provided.
Cautionary notes: the datum sentence should be transmitted immediately prior to
every positional sentence (e.g. GLL, BWC, WPL) which is referenced to a datum other
than WGS84, the datum recommended by IMO.
For all datums the DTM sentence should be transmitted prior to any datum change
and periodically at intervals of not greater than 30 s.
$--DTM,ccc,a,x.x,a,x.x,a, x.x,ccc*hh<CR><LF>
Reference datum
Altitude offset, m (see Note 3)
Lon offset, min, E/W (see Note 3)
Lat offset, min, N/S (see Note 3)
Local datum subdivision code (see Note 2)
Local datum:
(see Note 1)
NOTE 1
Three character alpha code for local datum. If not one of the listed earth-
centred datums, or 999 for user defined datums, use IHO datum code from
International Hydrographic Organisation Publication S-60, Appendices B and
C. Null field if unknown. This field should be set to 999 when manual offsets
are entered and in use by the position fixing device.
NOTE 2
One character subdivision datum code when available or user defined
reference character for user defined datums, null field otherwise. Subdivision
character from IHO Publication S-60, Appendices B and C.
NOTE 3
Latitude and longitude offsets are positive numbers, the altitude offset may
be negative. Offsets change with position: position in the local datum is
offset from the position in the reference datum in the directions indicated:
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