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NMEA Miscellaneous (MTW) - 23


Driver to decode values from the following NMEA sentences:


Rate Of Turn


Wind Direction & Speed


Wind Speed and Angle

The driver can convert the decoded relative wind values to a true wind vector, using the current vessel speed and course.
See Special Setup below for information about this.


Meteorological data (air temperature, pressure, humidity and dewpoint)


Seawater temperature


Meteorological Trend (temperature trend, pressure trend, humidity trend)

All values will be decoded as so-called generic observations.
This means that data is recorded, can be analyzed and monitored using the standard Qinsy displays, but are not used in any computation.

Driver Information

Driver  NMEA Miscellaneous Interface Type Serial Driver Class Type Terminated
UTC Driver (question) No Input / Output Input Executable DrvNMEAMiscellaneous.exe
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Decoding Notes

When observations are being decoded from a sentence that also contains quality information the quality information is automatically decoded as well and placed in the corresponding observation quality indicator field.

The observation quality indicator will be 1 when the reported status is 'Valid' and -1 when the status is 'Invalid'.

Database Setup

Add a miscellaneous system type to your template setup and select driver "NMEA Miscellaneous (MTW)", "NMEA Miscellaneous (ROT / MWD / MWV)" and/or "NMEA Miscellaneous (XDR / MTR)".

On the second wizard page, add one or more Generic observations and set the Slot Id as mentioned in the slot column of the tables above (case-sensitive).
It is recommended to select the Slot Id from the combo box. The observation name will then be set automatically, but you are free to change this name.

Special Setup

When decoding the relative wind vector from the NMEA MWV message, it is possible to convert the wind to a true wind direction and speed.

The true wind, relative to North, will be calculated using the decoded relative wind direction and speed, the vessel's own speed over ground, the vessel's own course over ground and the vessel's heading.

Notice that the wind direction is the direction where the wind is coming from, according the NMEA standard.

We have to tell the driver which vessel it should use for the calculation because it has no online user-interface and your template setup may have more than one vessel defined.

For this we shall use the assigned Slot Id:

Add to your template setup a miscellaneous system type, driver "NMEA Miscellaneous (ROT / MWD / MWV)", if you haven't done this already.

In order to decode the relative wind speed, add a generic observation and select from the Slot combo box 'MWV1'.
In order to decode the relative wind direction message, add a generic observation and select from the Slot combo box 'MWVR'.
Feel free to change the observation names, for example 'Rel Wind Speed' and 'Rel Wind Angle'.

Then, for the calculated absolute wind speed, add a generic observation and select from the Slot combo box 'MWV0_n'.
For the calculated absolute wind direction, add a generic observation and select from the Slot combo box 'MWVT_n'.

Important is to change the 'n' in the Slot: It should be the vessel object reference number.

When your setup has only one vessel defined, it will be 1. So in this case the slot becomes MWV0_1 and MWVT_1.

The exact object reference number can be found when you click in Database Setup on the object (vessel) on which the anemometer is mounted.
In the right pane you will see the number in the top.

Drivers IO Notes

Command line parameter NOCS disables the checksum checking.