Navigation:  Tutorials > Basic tutorials > Simple measurement > DEWESoft 7.0  data acquisition, processing, analyzing and storage software Channel setup

Click the Ch. setup button. This opens the channel setup where we see the Analog section with two analog channels (stereo), a Video section and Math section.

 

In the Storing section we can enter the file name and path where the files will be stored, in the Analog section is sample rate . A sample rate is the basic speed with which data will be acquired. This rate needs to be chosen wisely according to the specific situation. If temperatures are measured, we might need only 100 Hz (samples per second) or even less. If the number chosen is too high, we will waste disk space, yet gain no additional information.

In this case that we will measure sound, so we have to choose at least a sample rate of 10 kHz (10000 values per second) to really acquire sound correctly. For a good audio performance we should choose 40 kHz or more.

Next, the appropriate channels need to be selected. Since only a simple microphone is used for this example, only one channel is sufficient. The user can select it by clicking the on/off button. Note there are Setup buttons on the right side of the list.

Even though this is a simple microphone, the importance of correct measurement should be emphasized. First we need to define the Units of measurements. The physical quantity measured by a microphone is a sound pressure measured in Pascal. Pa should be entered as the unit.

 

Next we will try to perform a simple "calibration". Sound is calibrated with a sine wave. We can try to make a nice sine wave with a whistle. The RMS value of the signal grows to a certain level and we can use the Calibrate from RMS button to equalize the level to what might be approximately 1 Pa. A real microphone is calibrated exactly with the same method as used in this tutorial, but we can trust that the calibration value will be 1 Pa with the real microphone and calibrator.