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Aligning Wind Direction to True North vs. Magnetic North

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How to Reset Magnetic Declination on the Magellan MX Weather Station

The electronic compass in the Magellan MX Weather Station is aligned to Magnetic North. At the factory, the declination angle is set to correct wind direction output to True North based on the "Ship To" address. Once the declination angle is set in the sensor, it is stored permanently in non-volatile memory.

The declination angle needs to be reset only if the system is moved to a significantly different geographic location or if wind direction alignment to magnetic north is desired. Users can input the magnetic declination angle of any given geographic location using a terminal program such as HyperTerminal or PuTTY.

Magellan MX Weather Station

To Reset the Magnetic Declination

1. Determine the Correct Declination

The following web site may be helpful in determining the correct declination for your site:

Enter your zip code and click "Get & Add Lat/Lon". The latitude and longitude boxes will populate with values.

Click "Calculate".

The declination will be displayed in degrees (º) and minutes ('), e.g. 16º 27'. Divide the minutes by 60 to get a decimal remainder of degrees, e.g. 27 minutes = 0.45 degrees. The declination will be rounded up from 16.45 to 16.5 to conform to the data entry format of one decimal place.

2. Read or Set the Magnetic Declination

Once communication has been established a data string will be displayed in the terminal window once per second.

Press the * (asterisk) key to enter SETUP MODE.

The magnetic declination must be entered in ±XXX.X format.

For example, to set a declination value of +002.3 degrees type: COMPASSDECL +002.3 and press the Enter key.

If the entry is correct, then the sensor will report back with: New value saved (Advise to verify Compass Heading)

To verify the declination value (compass heading) type: COMPASSDECL and press the Enter key.

The declination value will be displayed; COMPASSDECL = +002.3

For a magnetic declination due West enter a negative number, for example: -010.1

Return to Measurement Mode by typing Q and pressing the Enter key.

The data string will resume displaying once per second.

Magnetic Declination


by Columbia Weather Systems

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