Furuno VR-3000 Operator's Manual page 38

DPT - Depth
IMO Resolution A.224 (VII). Water depth relative to the transducer and offset of the measuring
transducer. Positive offset numbers provide the distance from the transducer to the waterline.
Negative offset numbers provide the distance from the transducer to the part of the keel of
interest.
$--DPT, x.x, x.x*hh<CR><LF>
Checksum
Offset from transducer, in meters = distance from transducer to water-line
Water depth relative to the transducer, in meters
DTM - Datum reference (to be further developed)
Local geodetic datum to which a position location is referenced.
1 2 3 4 5 6 7
$--DTM, ccc, a,x.x,a,x.x,a,x.x,ccc*hh<CR><LF>
1) Local datum
WGS84 = W84
WGS72 = W72
SGS72 = S72
PE90 = P90
Under defined = 999
IHO datum code (see Note 1.)
Three character alpha code for local datum. If not one of the listed earth-centered datums, or 999 for
user difined 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.
2) Local datum subdivision code
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.
3) Lat offset, min, N/S (see Note2.)
4) Lon offset, min E/W (see Note2.)
5) Attitude offset, m (see Note2.)
6) Reference datum
WGS84 = W84
WGS72 = W72
SGS85 = S85
PE90 = P90
Note1: Users should be aware that chart transformations based on IHO S60 parameters may result in
significant positional errors when applied to chart data.
Note2: Lattitude and longitude offsets are positive numbers, the altitude offset may be negative. Off sets change
with position: position in the local datum is offset from the position in the reference datum in the directions
indicated:
P = P
local datum
When field 1 contains a value of 999, these fields may not be null, and should contain the manually entered or
user defined offsets.
28
8
+ Offset
ref datum