The compass shows the angle of your cell phone with magnetic north.


This instrument uses the various magnetometer data to calculate this angle.


The data accuracy is less than 0.1 degree and the data update rate is generally greater than 10 hertz, or 10 data per second. ",



Pedometer (number of steps)

The pedometer is an instrument that measures the number of steps you take

This calculation is done using data from the accelerometer which indicates when your movements seem to be regular enough to indicate that you are walking. By analyzing changes in your body's acceleration, the pedometer is able to identify when you take a step.


The pedometer only starts up when it detects a regularity in your walking movement. For this reason, you must first walk at least 7 steps forward so that it starts counting your steps.


The accuracy of this instrument depends on the length of your run but is usually one step per hundred steps.



One of the oldest measuring tools used by early architects is the plumb line. This instrument made it possible to know if a wall was vertical and was very important for constructing solid buildings.

The inclinometer of your smartphone has the same function and allows you to calculate the angle of your mobile in relation to the vertical.

Note: The angle you measure is the angle between the line that goes through the longest side of your smartphone and the vertical.

Accuracy: The accuracy of this instrument is 0.1 degree, and the update frequency is the same as the accelerometer, that is, less than 10 milliseconds.


Luxmeter (Illuminance or luminosity)

The ambient light sensor measures the illumination over a given area. The measurement is expressed in lux. A lux is the illumination of a surface which receives, in a uniformly distributed manner, a luminous flux of one lumen per square meter.

Note: Lux is a generally little known unit. When we buy light bulbs, we look at the number of watts and the number of lumens more often. Full moon generates about one lux, living room lamp about 50 lux, classroom lighting just like sunrise or sunset about 400 lux, indirect daylight more than 10 000 lux, while direct sunlight generates more than 30,000 lux.

Precision: The frequency of data updates depends on the sensors of your cell phone and is generally greater than 10 hertz, or 10 data per second


Colors (Colorimeter)

The colorimeter is a tool that analyzes colored samples. FizziQ uses the photographic detector in your mobile phone to calculate different parameters that characterize the color reflected or transmitted by the objects you are analyzing.

Color is a difficult physical phenomenon to study. Everyone perceives colors differently. Cellular photographic sensors have different sensitivities at certain wavelengths, and results are not always comparable for different notebooks.

The Color screen gives you a lot of information about the color of the center of the image: a sample of the color perceived by the sensor and its common name, the spectrum in% of the maximum value of the components red, green and blue that make up that color, the tint on the HSV scale, and the intensity of that tint.


RGB color spectrum (Colorimeter)

The English scholar Thomas Young was the first to discover that three monochromatic colors, red, green and blue, suffice to obtain by addition all the sensations of color. Our retina is also made up of detectors called cones which have specific sensitivities to each of these colors.

A digital camera works in a similar way. On the sensor, is attached a network of small filters of red, green and blue, called a Bayer filter. This filter lets the wavelengths pass around the 460 nm (blue), 550 nm (green) and 640 nm (red) wavelengths.

Your laptop makes many adjustments to ensure that the image is always clear and colors are represented well, but this can affect your measurements if you compare different colors. It is therefore recommended to press the Expo button to set the parameters of your device when you want to compare different colors.


Local and global luminance (Colorimeter)

The smartphone camera can calculate the luminance of the luminous flux which is emitted or reflected by the objects which are in its field. The luminance is proportional to the light intensity but, unlike the illumination measurement, does not take into account the surface of the light source. It is the visual feeling of the light intensity.

Local luminance calculates the luminance of the central pixels of the image captured by the camera. Global luminance calculates the average luminance over all the pixels of the camera image.

In FizziQ, the luminance is calculated as the average of the red, green and blue components detected by the smartphone camera over the entire image and referred to the calibration value. The measurement is updated at a frequency of approximately 10 Hz.

WARNING: the smartphone constantly adjusts its light sensors so that the image is the best possible, it is therefore necessary to calibrate the instrument, which makes it possible to set the image acquisition parameters and therefore to be able to compare the images. luminance that you observe compared to the initial luminance.

Absorbance (Colorimeter)

Absorbance measures the ability of a medium to absorb light passing through it. This measurement is used in spectrometry to measure the concentrations of chemicals. Absorbance is the decimal logarithm of the ratio between the reference light intensity and the transmitted light intensity.

Absorbance is a relative dimensionless datum. The measuring device should be calibrated using the CAL button, which will set the reference light intensity. The reset button is used to cancel the calibration.

Your smartphone cannot be compared to a laboratory spectrometer that can take high-precision measurements, but it does allow you to perform some exciting experiments on light. ",


Linear acceleration measures the variation in the speed of your mobile (in the terrestrial frame of reference) along the three axes X, Y and Z. It is measured in m / s². The value is therefore zero (along all axes) when the telephone is stationary.

The accelerometer measures the intensity of all the forces exerted on your mobile and expresses them in the form of an acceleration. If you shake your mobile and therefore apply forces to it, you will see the measurement increase or decrease rapidly.

Note: "absolute" acceleration

If you keep your cell phone still, you will find that the accelerometer displays a value of approximately 9.8 m / s².

This acceleration results from the force you exert to keep your mobile phone stationary and counter the force of weightlessness. Make a particular paragraph for absolute acceleration ??

Some smartphones provide access to another measure of acceleration: linear acceleration. This measurement is in fact the combined result of two sensors: the accelerometer with g, and the magnetometer. The latter makes it possible to subtract the component of the severity of the measurement. Linear acceleration is thus a measurement that only reflects the acceleration created by the user without gravity, as if you were in zero gravity! This measurement is very useful for games where only the user's movement matters.


Your smartphone's accelerometer is very precise. The measurement accuracy is less than 0.01 m / s², and the data update rate is greater than 100 hertz, that is, 100 data is calculated per second.


Sound level meter (microphone-sound volume)

The sound level meter measures the sound volume picked up by the microphone. It is expressed in decibels, or dB.


The decibel scale is logarihmic: a 40dB source is 100 times louder than a 20dB source.The quietest sound a human ear can hear is zero decibels. Ordinary conversation reaches around 60 dB, the sound of a mixer is often 90 dB, and sounds above 140 dB are painful to the human ear. Continuous exposure to sounds over 90 dB can cause hearing loss.


The data update rate is greater than 250 hertz, that is, 250 measurements per second.

Smartphones have more or less sensitive microphones, and the volume measurement will vary from one to another. The software calibrates the device so that the loudest sound observed over a period of time is 90 dB and the quietest is 20 dB. It therefore produces a measure of the relative power of sound rather than an absolute measure.

Bone sound cillogram (Microphone-amplitude)

An oscillogram gives a temporal representation of a signal by measuring the variations in its intensity (or amplitude) over time.

Both periodic and non-periodic signals can be represented by an oscillogram, but only those that exhibit periodicity will have a stable representation over time.


To create the oscillogram, your smartphone records the signal over small time intervals, then synchronizes these recordings in order to start the sequence always in the same place of it. For example, he can start the sequence when the maximum is reached.

The oscillogram time scale is 10 milliseconds. Amplitude is expressed as a percentage of the maximum amplitude that the microphone can detect.

Frequency meter (Microphone-frequency)

The frequency of a signal corresponds to the number of repetitions per second of the elementary pattern that composes it. It is expressed in hertz, noted Hz.

A sound is usually made up of several pure tones with different frequencies. The frequency meter gives the frequency of highest intensity among all the frequencies that compose it: the dominant frequency.


To calculate this frequency, the frequency meter records the sound of the microphone over small time intervals. Then, using a mathematical process called the Fourier transform, it calculates the frequencies of all pure tones and the loudness of those tones. It then deduces the dominant sound which is the frequency with the highest sound intensity.

It is expected that a future version will systematically give the frequency of the fundamental so as not to have (sometimes) the frequency of the harmonic of greater amplitude. When this modification is effective, we will indicate it in the sensor information on the application. We will then integrate a new measuring instrument making it possible to display the "note" heard since this note depends directly on the frequency of the fundamental (for example, an A4 corresponds to a frequency of the fundamental of 440 Hz) (I would like to add this , what do you think ?)


The frequency… Can we supplement ??


Frequency Spectrum (Microphone-spectrum)

Unlike the frequency meter which only gives the dominant frequency of a sound (or that of its fundamental sound depending on the version), the sound spectrum details all the frequencies that compose it. This tool thus makes it possible to precisely describe the characteristics of a sound.

The greater the number of frequencies that make up the note, the more “rich” the sound is said to be. This contributes to the "timbre" of an instrument.


The frequencies are expressed in hertz, noted Hz. The amplitude is expressed as a percentage of the maximum amplitude that the microphone can detect.


Data is refreshed every 0.5 seconds.



The magnetometer calculates the global magnetic field to which your cell phone is subjected. The measurement is expressed in microTesla, denoted μT.


Your phone's magnetometer is very sensitive to electrical currents and metallic objects. Metal detectors use magnetometers. Of course, your magnetometer also detects the earth's magnetic field, which varies between 20 and 80 μT depending on the location.


The sensitivity of magnetometers in smartphones is generally less than 0.2 μT. Most of the time, the data update rate is greater than 50 hertz, or 50 data per second.



A gyroscope is an instrument that measures the orientation of an object in space.

The speed of rotation is measured in rpm, which corresponds to the number of revolutions per minute.

The rotation of your mobile can be measured in relation to the 3 axes of your phone (X, Y and Z)

Your smartphone has gyroscopes that allow you to determine the speed of rotation of the mobile on itself in all directions. This is very useful for games, for example when you use your mobile to control a car or a character.

Facial rotation is the rotation of your mobile with respect to the z axis, which is perpendicular to the face of the smartphone. Longitudinal rotation is the rotation around the y axis which is the length of your cell phone. If you put your cell phone in a cylinder, you can use this sensor to detect if your cell phone is running and at what speed


Your smartphone has gyroscopes that allow you to determine the speed of rotation of the mobile on itself in all directions. This is very useful for games, for example when you use your mobile to control a car or a character.

Gyroscopes are essential for the navigation of airplanes or satellites and allow them to detect whether they are pointing up, down or to the side. Usually a gyroscope is made up of a wheel or disc that spins around another disc or axis. The rotation of the discs measures both the orientation of the gyroscope itself and the speed at which it spins in one direction or the other.

If you put your cell phone in a cylinder, you can use this sensor to detect if your cell phone is running and at what speed


GPS allows you to calculate the position of your mobile on Earth. A point on the earth's surface is characterized by its latitude and longitude.

Latitude: Latitude is the angle formed between the vertical of a place and the plane of the equator: from + 90 degrees North towards the North Pole to - 90 degrees towards the South Pole.

FizziQ expresses the latitude in millidegrees (1 millidegree = 0.001 degree).

Longitude: Longitude is the angular value of the east-west position of a point relative to the reference longitude on Earth, the Greenwich meridian. FizziQ expresses longitude in millidegrees.

Speed: GPS By analyzing the changes in this position, your smartphone deduces the speed of your smartphone. The accuracy of this instrument for measuring speed is generally less than 1 m / s.

Altitude: The GPS allows you to calculate the position of your mobile on the earth. The system is also able to give the altitude above sea level where your mobile is located.


The data is updated every second. The accuracy of the GPS for the position is usually around ten meters.

The precision display has been integrated into this measuring device. You can therefore display the measurement accuracy of your GPS using the Precision instrument.

This precision gives a measure of the margin of error of your GPS. It is expressed in meters. An Accuracy of 10 meters indicates that the position of your smartphone is accurate to within 10 meters.

The GPS system works by receiving information from satellites that revolve around the earth. For optimum accuracy, the GPS must receive information from at least four satellites. The signal hardly crosses obstacles such as walls or trees. To improve the accuracy of your measurements, make sure you are in open terrain, with no obstacles between you and the sky.

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