INTERNSHIP/THESIS - Automatic Level Control (ALC) calibration algorithm

One of our core tasks in Televic GSP is to develop and provide audio systems to be used onboard of railway vehicles. These systems are used for crew communication and public announcements (PA). Related to PA we deliver an automatic system that configures the preferred broadcast volume based on the environmental noise. When the system is idle the connected speakers behave as microphones to measure the noise. To ensure optimal intelligibility and signal to noise ratio (SNR) , the system needs to be calibrated for each speaker branch on the amplifiers that are implemented on the vehicle.

To perform a valid calibration we need to perform measurements in static and dynamic (driving) conditions. Ideally this happens on a test track where a constant speed and noise can be maintained. And all of this happens manual up till now.

The goal of this project is to develop a tool that uses an algorithm that determines the relationship between the noise that is being picked up by the onboard system and measurement microphones that are distributed in the vehicle. The output of the algorithm needs to contain the calibration data that needs to be added to the system’s software package, as well as some details regarding the measurements ( e.g. RMS / FFT graphs). The tool should make it possible to perform the measurements on public tracks. This would give a us a lot of flexibility and also decrease the necessary cost for executing such measurements.