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Method and apparatus for calculating azimuth

  • US 10,267,649 B2
  • Filed: 04/02/2014
  • Issued: 04/23/2019
  • Est. Priority Date: 07/24/2013
  • Status: Active Grant
First Claim
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1. An apparatus comprising:

  • a magnetic sensor configured to sense a magnetic field and convert the sensed magnetic field into a voltage;

    an amplifier configured to amplify the voltage;

    an analog-to-digital converter configured to convert the amplified voltage into voltage data; and

    a processor configured to execute instructions stored in a memory, thereby configuring the processor to;

    separate the voltage data into 3-axis magnetic field components in X, Y and Z axes to generate separated voltage data;

    remove noise components of the separated voltage data by creating a median value of the separated voltage data and filtering the separated voltage data by selecting midmost voltage data;

    apply a previously calculated offset to the filtered separated voltage data;

    determine, based on the application of the previously calculated offset, whether the filtered separated voltage data correspond to a geomagnetic field;

    selectively, based on a result of the determining of whether the filtered separated voltage data correspond to the geomagnetic field,select offset data items from the filtered separated voltage data,subtract a difference between the filtered separated voltage data and previously measured voltage data from a previous offset reference point,set a resultant value as a new offset reference point, in response to the filtered separated voltage data being determined not to correspond to the geomagnetic field and the previously measured voltage data being determined to correspond to the geomagnetic field, andcalculate an offset by a geometrical method that uses the selected offset data items and the new offset reference point; and

    determine a location or directional information of the apparatus based on the voltage data for the sensed magnetic field and selectively one of the calculated offset and the previously calculated offset, with increased location or directional determination speed and/or accuracy with respect to a presence of an abnormal magnetic field.

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