Companding techniques for high dynamic range audio CODEC receiver path

Abstract

In this thesis, an audio CODEC receiver path has been modified by the addition of companding techniques. Companding compresses the input signal and expands the output signal according to the input power strength such that additional noise from the system is suppressed while the signal content is maintained. As the compression level is varied according to the input signal strength, transients occur at the output of the system. Sudden changes in the compression level cannot be processed instantaneously and generate transients in the output. The thesis first statically demonstrates that companding can increase the signal to noise ratio and improve the dynamic range of the audio CODEC Rx path by up to 18 dB. Further, two compensation techniques are analyzed in attempt to reduce the companding transients. The results show that transients in the output are reduced on average by 60% when using either compensation technique.