If we measure the same situation with more mobile phones, we find out that
displayed data are different.

To create a noise map of the town, we need to use more mobile phones.
So we have to calibrate them.

In a big room, we put the best sound meter far enough from a speaker
and next to it we put a phone which we want to calibrate.
The microphones of both devices must be facing the same direction.

The calibration process:

1. We will create a white noise.
2. We will gradually set PC's volume so that the sound meter shows values
   of 30, 40, 50, 60, 70, 80 dB
3. We will note data from the sound meter into a table.

We will put the measured data into LoggerPro program and
we will examine which function is suitable for the description of dependance.
Suitable function:

Unsuitable function


For our calibration is suitable the function y = ax+bx which has parameters a, b
X- data measured from a phone    Y - real accurate data

For every phone it is important to make a table of measured data and
create a special calibrating equation.

Test

In conclusion we will test given methods.
In a room we will create a sound of constant volume.
We will prepare 2 different phones and we will read shown data.
The phones have these calibrating equations:
 

We will input the measured data into calibrating equations and
there should appear almost the same results.

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