Automatic Calibration and Equalization of a Line Array System

摘要

This final project presents an automated Public Address processing unit, using delay and magnitude frequency response adjustment. The aim is to achieve a flat frequency response and delay adjustment between different physically-placed speakers at the measuring point, which is nowadays usually made manually bythe sound technician. The adjustment is obtained using four signal processing operations to the audio signal: time delay adjustment, crossover filtering, gain adjustment, and graphic equalization. The automation is in the calculation of different parameter sets: estimation of the time delay, the selection of a suitable crossover frequency, and calculation of the gains for a third-octave graphic equalizer.These automatic methods reduce time and effort in the calibration of line-array PA systems, since only three sine sweeps must be played though the sound system. For verifying the functioning of the system, both simulated signals and measurements have been conducted. A 1:10 scale model of a line array system has been designed and constructed in an anechoic chamber to test the automatic calibration and equalization methods and the results are analyzed.