GEODETICDATUM
Set user-defined datum parameters
|
Platform: |
OEM719, OEM729, OEM7500, OEM7600, OEM7700, OEM7720, PwrPak7, CPT7, CPT7700, SMART7, SMART2 |
Use this command to add or remove user-defined datums. These are used by the OUTPUTDATUM command to select an entry from the DATUMTRANSFORMATIONS log. They also define the parameters to convert between geodetic and Cartesian coordinates.
The OUTPUTDATUM command must be sent for any user-defined datums to be output.
The receiver firmware includes a default set of datums. These default datums cannot be deleted, but can be overwritten with user-defined parameters. A default datum that has been overwritten can be reverted to the default parameters by deleting the datum. User-defined datums will persist a factory reset; all user-defined datums can be removed by sending FRESET USER_DATUM (see the FRESET command). Both the user-defined and default datums are reported by the GEODETICDATUMS log.
Datum entries are indexed by name, which must be unique. The name “USER” is reserved for the USEREXPDATUM entry. “ECEF” is reserved as a generic Earth-Centered Earth-Fixed datum. “UNKNOWN” is also reserved.
The EPSG Geodetic Parameter Dataset (epsg.io) is a commonly-referenced database of coordinate reference systems and coordinate transformations. The EPSG code in this log is intended to correspond to the “GeodeticDatum” data type within that database. If you are using a custom datum, the ESPG code should be 0.
Message ID: 2295
Abbreviated ASCII Syntax:
GEODETICDATUM switch name epsg_code anchor semimajor_axis flattening
Factory Default:
GEODETICDATUM none
ASCII Example:
Save a new geodetic datum to NVM:
GEODETICDATUM save NAD83(MA11) 1118 EARTH_FIXED 6378137.0 298.257222101
Delete an existing geodetic datum from NVM:
GEODETICDATUM delete NAD83(MA11)
|
Field |
Field Type |
ASCII Value |
Binary Value |
Description |
Format |
Binary Bytes |
Binary Offset |
|---|---|---|---|---|---|---|---|
|
1 |
Command header |
– |
– |
GEODETICDATUM header This field contains the command name for abbreviated ASCII or the message header for ASCII (see page 1) or Binary (see page 1). |
– |
H |
0 |
|
2 |
switch |
SAVE |
1 |
Save the datum. |
Enum |
4 |
H |
|
DELETE |
2 |
Delete the datum. |
|||||
|
3 |
name |
|
Name of the datum. |
Char |
variable |
H+4 |
|
|
4 |
epsg_code |
|
The EPSG code. |
Ulong |
4 |
variable |
|
|
5 |
anchor |
The datum type. |
Enum |
4 |
variable |
||
|
6 |
semimajor_axis |
6300000.000 – 6400000.000 |
Semi-major axis of the datum's ellipsoid (metres) |
Double |
8 |
variable |
|
|
7 |
flattening |
290.000 – 305.000 |
Inverse flattening of the datum's ellipsoid (unitless) |
Double |
8 |
variable |
|