Graphic VU meter display for sound mixers implemented using FPGA

Abstract

'Mixing' is the process of manipulating and combing various audio signal sources into one final output. This is achieved by using an analogue or digital audio mixer in concerts and theatres. Given the increase in public events and thus the need for sound mixing, it is a must to provide some means of visual display as to what the sound engineer is mixing and what is the final result. This final year project focuses on achieving a visual display of sixteen separate input channels, together with the possibility of performing a real-time Fast Fourier Transform (FFT), using the Cooley-Tukey algorithm on one channel selected by the user. These algorithms are realised using VHSIC Hardware Description Language (VHDL) and are implemented on a Field Programmable Gate-Array (FPGA). The aim of this project is to achieve a system-on-chip architecture which hosts all the digital components on a single chip thus reducing delays. This allows for increased clock speeds and for high parallelism given the design architecture of FPGAs. Particular importance is also given to the fact that some operations must be performed very fast. This is the case with the FFT since the time to process an N-point FFT is proportional to N log2 N given there are no copying and routing delays. Thus, it is necessary to program some algorithm which does not lose or keeps the losses of the sampled data points down to a minimum.