Sound card Oscilloscope / Generator Manual: Introduction

Index

• Introduction

• Calibration

• Features

Calibration

• Type of transducer: Most PC microphones are of the electret type (permanently polarized condenser), powered by a polarization voltage typically between 2 and 5 V
  supplied by the sound card via the jack or USB input.
• Input impedance: Typically between 1 kΩ and 10 kΩ, which is suitable for a standard audio interface. This allows for good matching with the input circuits of sound cards.
• Sensitivity and bandwidth:
  • Sensitivity: around –40 to –60 dBV/Pa, which means they pick up close sounds well but are limited for weak or distant signals.
  • Bandwidth: usually 100 Hz to 10 kHz, sufficient for voice but limited for high-fidelity audio applications or precise measurements.

👉 Thus you should setup the software with the actual peak volts values your sound card is setted up for, in order to read the actual Volt values on the oscilloscope.

That means to know wich is the Voltage value for the maximum and minimum digital value, according to the bit sample resolution, from 0 to 2^n-1 where n is the number of bits given by the ADC

👉 You can get more information about polarized electret microphones here : https://www.epanorama.net/circuits/microphone_powering.html#soundcard

How to calibrate the intput peak Volt values

Click on the button Settings on the right menu (oscilloscope menu), then on the tab Input:

ℹ️information: If the right menu is not visible, click on the upper top right button Toggle menu to expand it.

Click the field Signal Range and then setup the value using the input widget. This is the polarized pick value, meaning a range of -value .. +value