Basic idea was to make a VU meter that captures signal with a built-in microphone or a audio socket. For data processing was used Teensy 3.2 microcontroller soldered together with the audio card for faster data processing. Teensy 3.2 can be programmed in program »Arduino sketch«, which is based on programming language »C++«.
Two LED strips were used to display current power of detected signal. Each LED strip for each channel.
Later was added LCD screen with resolution 320x240 pixels. On display is shown active input and signal strength level.
Additionally, was added line-out on which we can connect headphones and listen to the processed noise detected on input.
A calibration was done for microphone in anechoic chamber in faculty.
Additionally, was implemented frequency weighting (»A«), which is widely used in noise meters and is defined in the standard IEC 61672: 2013. Its purpose is to bring the microphone's response closer to the human ear, so the process unit exclude unnecessary frequencies that contribute to the calculation of noise that the human ear does not detect.
At the end, all parts were assembled together into the housing, which was drew in Creo parametric and was created with the 3D printer.
The final version of the noise meter displays the signal strength level on the screen and LED strips, or the signal is captured by a phone that plays music.