UNDULATION

Chooses undulation

Platform:

OEM719, OEM729, OEM7500, OEM7600, OEM7700, OEM7720, PwrPak7, CPT7, CPT7700, SMART7, SMART2

This command permits you to enter a specific geoidal undulation value. In the option field, the EGM96 table provides ellipsoid heights at a 0.5° by 0.5° spacing while the OSU89B is implemented at a 2° by 3° spacing. In areas of rapidly changing elevation, you could be operating somewhere within the 2° by 3° grid with an erroneous height. EGM96 provides a more accurate model of the ellipsoid which results in a denser grid of heights. It is also more accurate because the accuracy of the grid points themselves has also improved from OSU89B to EGM96. For example, the default grid (EGM96) is useful where there are underwater canyons, steep drop-offs or mountains.

The undulation values reported in the position logs are in reference to the ellipsoid of the chosen datum.

Refer to the application note APN-006: Geoid Issue, available at novatel.com/support/support-materials/application-notes, for a description of the relationships in Figure: Illustration of Undulation.

Illustration of Undulation

Message ID: 214

Abbreviated ASCII Syntax:

UNDULATION option [separation]

Factory Default:

UNDULATION egm96 0.0000

ASCII Example 1:

UNDULATION osu89b

ASCII Example 2:

UNDULATION USER -5.599999905

Field

Field Type

ASCII Value

Binary Value

Description

Format

Binary Bytes

Binary Offset

1

Command header

-

-

UNDULATION 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

option

USER

1

Use the user specified undulation value

Enum

4

H

OSU89B

2

Use the OSU89B undulation table

EGM96

3

Use global geoidal height model EGM96 table

3

separation

±1000.0 m

The undulation value (required for the USER option) (default = 0.000)

Float

4

H+4