QMagnetometerReading Class

The QMagnetometerReading class represents one reading from the magnetometer. More...

Header: #include <QMagnetometerReading>
qmake: QT += sensors
Since: Qt 5.1
Inherits: QSensorReading

Properties

Public Functions

QMagnetometerReading(QObject *parent = DECLARE_READING(QMagnetometerReading))
virtual ~QMagnetometerReading()
qreal calibrationLevel() const
void setCalibrationLevel(qreal calibrationLevel)
void setX(qreal x)
void setY(qreal y)
void setZ(qreal z)
qreal x() const
qreal y() const
qreal z() const

Reimplemented Public Functions

virtual void copyValuesFrom(QSensorReading *other) override

Additional Inherited Members

  • 1 public slot inherited from QObject
  • 2 signals inherited from QObject
  • 1 public variable inherited from QObject
  • 10 static public members inherited from QObject
  • 9 protected functions inherited from QObject
  • 2 protected variables inherited from QObject

Detailed Description

The QMagnetometerReading class represents one reading from the magnetometer.

QMagnetometerReading Units

The magnetometer returns magnetic flux density values along 3 axes. The scale of the values is teslas. The axes are arranged as follows.

The magnetometer can report on either raw magnetic flux values or geomagnetic flux values. By default it returns raw magnetic flux values. The QMagnetometer::returnGeoValues property must be set to return geomagnetic flux values.

The primary difference between raw and geomagnetic values is that extra processing is done to eliminate local magnetic interference from the geomagnetic values so they represent only the effect of the Earth's magnetic field. This process is not perfect and the accuracy of each reading may change.

The image below shows the difference between geomagnetic (on the left) and raw (on the right) readings for a phone that is being subjected to magnetic interference.

The accuracy of each reading is measured as a number from 0 to 1. A value of 1 is the highest level that the device can support and 0 is the worst.

Calibration

If the device is reporting low accuracy, then calibration might be needed before acceptable measurements can be provided. Basic calibration can usually be done by either rotating your device in a figure of eight, or by rotating the device along each of its three axes. For more information, check your device's documentation on how to calibrate the magnetic sensor.

Property Documentation

calibrationLevel : const qreal

This property holds the accuracy of the reading.

Measured as a value from 0 to 1 with higher values being better.

Note that this only changes when measuring geomagnetic flux density. Raw magnetic flux readings will always have a value of 1.

Access functions:

qreal calibrationLevel() const

See also QMagnetometerReading Units and Calibration.

x : const qreal

This property holds the raw magnetic flux density on the X axis.

Measured as teslas.

Access functions:

qreal x() const

See also QMagnetometerReading Units.

y : const qreal

This property holds the raw magnetic flux density on the Y axis.

Measured as teslas.

Access functions:

qreal y() const

See also QMagnetometerReading Units.

z : const qreal

This property holds the raw magnetic flux density on the Z axis.

Measured as teslas.

Access functions:

qreal z() const

See also QMagnetometerReading Units.

Member Function Documentation

QMagnetometerReading::QMagnetometerReading(QObject *parent = DECLARE_READING(QMagnetometerReading))

Default constructs an instance of QMagnetometerReading.

[virtual] QMagnetometerReading::~QMagnetometerReading()

Destroys the instance of QMagnetometerReading. The destructor is virtual.

[override virtual] void QMagnetometerReading::copyValuesFrom(QSensorReading *other)

void QMagnetometerReading::setCalibrationLevel(qreal calibrationLevel)

Sets the accuracy of the reading to calibrationLevel.

See also calibrationLevel().

void QMagnetometerReading::setX(qreal x)

Sets the raw magnetic flux density on the X axis to x.

See also x().

void QMagnetometerReading::setY(qreal y)

Sets the raw magnetic flux density on the Y axis to y.

See also y().

void QMagnetometerReading::setZ(qreal z)

Sets the raw magnetic flux density on the Z axis to z.

See also z().

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