The paper considers the development of a low-cost acoustic sensor based on an
import-substituting element base as a cheap alternative to professional sensors or
analog sensors.
The following components were used in the design: an Arduino board for easy
prototyping; a MAX9812 microphone module sensing frequencies 20 - 20000 Hz;
a microSD card module, an RTC sensor, a 32 GB microSDHC card, an IP65
enclosure, a printed breadboard for soldering, a battery compartment, a
microphone diaphragm and a key switch were selected because of their
availability; the NB-IoT module - SIM7080G was chosen for data exchange with
the server; 3 Li-ion Cosmos batteries at 1800 mAh were selected for autonomous
operation of the sensor.
After checking the sensor performance on the breadboard, it was assembled into
the case, drilling and machining a hole for the microphone and key switch output.
To improve the accuracy of the data taken from the microphone, it was calibrated
using a reference noise meter, using a regression method to calculate the sound
level in decibels, and obtained an equation for converting the obtained ADC values
into decibels.
The code of the program executed by the sensor was developed and sewn into the
device. The data captured from the microphone is stored in a text file with the date
and time of the captured data.
A prototype of an import-substituting noise sensor was designed for use in
production and the workplace. All available components have been selected for it
and the IP65 dust and moisture protection level has been achieved.
The sensor is ready for further improvement, namely the addition of a user
interface, easier access to data, the development of its own housing, and eventually
mass production.