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UNITS.md

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One-Page Unit Reference

This page is a comprehensive documentation of the units of values reported in the Sensor Logger app. Much effort has been spent to ensure correctness and consistency across iOS and Android. Should you notice any error, please report by making an Issue or make a pull request directly. Additional information about sensors and measurements is available in-app by tapping the "eye" icon next to each sensor.

For full documentation, please visit https://www.tszheichoi.com/sensorloggerhelp

Time

  • time is in nanoseconds since epoch. For more information about conversion, use tools like https://www.epochconverter.com/.
  • seconds_elapsed is in seconds since the start of the recording.

Accelerometer

  • x, y and z in meters per second squared (ms-2); Assumes g to be 9.80665ms-2.

See the Coordinates Reference for definitions of axes.

Accelerometer Uncalibrated

  • x, y and z:
    • On iOS, this is in standard gravity (g), when "Standardise Units & Frames" is off (default). The unit is ms-2 when "Standardise Units & Frames" is on.
    • On Android, this is in meters per second squared (ms-2).

💡: Toggling Standardise Units & Frames under Settings > Sensor Configuration removes all platform-dependent units and coordinate systems differences.

Gravity

  • x, y and z, in meters per second squared (ms-2); Assumes g to be 9.80665ms-2.

Gyroscope

  • x, y and z, in radians per second (rad/s).

Gyroscope Uncalibrated

  • x, y and z, in radians per second (rad/s).

Orientation

  • pitch, roll and yaw, in radians.
  • qx, qy, qz and qw, dimensionless.

See the Coordinates Reference for definitions of axes. Note that the yaw definition is different between iOS and Android.

Pedometer

  • steps is an integer.

Location

  • altitude, in meters as a height above the WGS84 ellipsoid.
  • altitudeAboveMeanSeaLevel, in meters above mean sea level (iOS Only).
  • bearing, in degrees from 0 to 360 relative to due north. Negative values indicate it is invalid.
  • bearingAccuracy, in degrees. Negative values indicate it is invalid.
  • horizontalAcccuracy, in meters as the radius of uncertainty. It is approximately the unit standard deviation around the altitude. Negative values indicate it is invalid.
  • verticalAccuracy, in meters. It is approximately the unit standard deviation around the altitude. Negative values indicate it is invalid.
  • speed, in meters per second. Negative values indicate it is invalid. Note this is derived from the location, so may be unreliable if the speed changes between location updates.
  • speedAccuracy, in meters per second. Negative values indicate it is invalid.
  • latitude, in degrees. Positive values are north of the equator (-90 to 90)
  • longitude, in degrees. Positive values are east of the meridian line (-180 to 180).

Magnetometer

  • x, y and z, in micro teslas.

Uncalibrated Magnetometer

  • x, y and z, in micro teslas.

Barometer

  • relativeAltitude is in meters since the start of the recording.
  • pressure is in mBar.

Microphone

For more information about the audio file, see https://github.com/tszheichoi/awesome-sensor-logger/blob/main/MICROPHONE.md

Network

  • type can be one of none, unknown, cellular, wifi, Bluetooth, ethernet, wimax, vpn or other.
  • isConnected is a boolean or null.
  • isInternetReachable is boolean or null.
  • isWifiEnabled is boolean (Android only).
  • isConnectionExpensive is boolean.
  • ssid is a string.
  • bssid is a string.
  • strength is a number between 0 and 100.
  • ipAddress is the external IP address. Can be IPv4 or IPv6.
  • frequency is the network frequency. For example, 2.4GHz will return 2457.
  • cellularGeneration can be one of 2g, 3g, 4g, 5g or null.
  • carrier is a string.

Brightness

  • brightness is between 0 and 1, representing the relative screen brightness.

Annotation

  • millisecond_press_duration is how long the pencil icon was tapped, in milliseconds.
  • text is the text string entred by the user.

Battery

  • batteryLevel is between 0 and 1, representing the fractional charge level.
  • batteryState is an enum that can be one of unplugged, charging or full.
  • lowerPowerMode is a boolean.

Headphone

  • pitch, roll and yaw, in radians.
  • accelerationX, accelerationY and accelerationZ in standard gravity (g), when "Standardise Units & Frames" is off (default). The unit is ms-2 when "Standardise Units & Frames" is on.
  • gravityX, gravityY and gravityZ, in meters per second squared (ms-2); Assumes g to be 9.80665ms-2, regardless of whether "Standardise Units & Frames" is turned on or not.
  • quaternionW, quaternionX, quaternionY and quaternionZ, dimensionless.
  • devicelocation can be left or right.
  • rotationRateX, rotationRateY and rotationRateZ, in radians per second (rad/s). (Note: New in version 1.30)

💡: Toggling Standardise Units & Frames under Settings > Sensor Configuration removes all platform-dependent units and coordinate systems differences.

Heartrate

  • bpm in beats per minute.

WristMotion

  • rotationX, rotationY and rotationZ, in radians per second (rad/s).
  • gravityX, gravityY and gravityZ, in standard gravity (g), when "Standardise Units & Frames" is off (default). The unit is ms-2 when "Standardise Units & Frames" is on.
  • accelerationX, accelerationY and accelerationZ in standard gravity (g), when "Standardise Units & Frames" is off (default). The unit is ms-2 when "Standardise Units & Frames" is on.
  • quaternionW, quaternionX, quaternionY and quaternionZ, dimensionless. Note that if you require pitch, roll and yaw information, you can derive them from the quaternions, which are more suitable for most applications anyways.

💡: Toggling Standardise Units & Frames under Settings > Sensor Configuration removes all platform-dependent units and coordinate systems differences.

Light

  • lux is in lux.

WiFi

  • ssid is the name of the WiFI network.
  • bssid is the MAC address.
  • frequency is the network frequency.
  • level is the signal strength in dBm.

Compass

  • magneticBearing is in degrees.