Design of a Digital Octave Band Filter

• Main Author: Lindblom, Ludvig
• Format: Others
• Language: English
• Published: Linköpings universitet, Elektroniksystem 2012
• Subjects: Digital filters; multirate filtering; audio processing
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-79231

This report describes the design and implementation of a fixed audio equalizer based on a scheme where parts of the signal spectrum are downsampled and treated differently for the purpose of reducing the computational complexity and memory requirements. The primary focus has been on finding a way of taking an equalizer based on a simple minimum-phase FIR filter and transform it to the new type of equalizer. To achieve this, a number of undesireable effects such as aliasing distortion and upsampling imaging had to be considered and dealt with. In order to achieve a good amplitude response of the system, optimization procedures were used. As part of the thesis, a cost-effective implementation of the filter has been made for an FPGA, in order to verify that the scheme is indeed usable for equalizing an audio signal.