Smart EQ Digital Stereo Equalizer Dustin Demontigny David Bull

March 2003 Smart EQ 2 Project Motivation Optimize an audio signal for a specific individual Optimize an audio signal for a specific individual Improve on existing analog equalizer systems Improve on existing analog equalizer systems Apply DSP techniques using VHDL Apply DSP techniques using VHDL

March 2003 Smart EQ 3 Design Goals Develop 10 band stereo equalizer Develop 10 band stereo equalizer User interface and control User interface and control Minimize FPGA resources of filter Minimize FPGA resources of filter High level of resolution (20 bit audio samples) High level of resolution (20 bit audio samples)

March 2003 Smart EQ 4 Audio Interface Combines the XStend and XSA-100 boards Combines the XStend and XSA-100 boards FPGA controls the AKM sigma delta codec on XStend board FPGA controls the AKM sigma delta codec on XStend board

March 2003 Smart EQ 5 VHDL Modules User interface selects equalizer settings User interface selects equalizer settings ROM on arithmetic unit holds taps ROM on arithmetic unit holds taps Handshaking between sections Handshaking between sections EQ interfaces to codec and provides filtering EQ interfaces to codec and provides filtering

March 2003 Smart EQ 6 User Interface Push buttons toggle between preset values Push buttons toggle between preset values Preset number displayed on LED Preset number displayed on LED Gain value decoded from preset value Gain value decoded from preset value Simple but very small (only 3% of FPGA) Simple but very small (only 3% of FPGA)

March 2003 Smart EQ 7 Arithmetic Unit Receives gain value and determines the filter coefficients Receives gain value and determines the filter coefficients Retrieves filter taps from ROM Retrieves filter taps from ROM Reduces total taps by a factor of the bands (in our case 10) Reduces total taps by a factor of the bands (in our case 10)

March 2003 Smart EQ 8 Equalizer 10 bandpass FIR digital filters 10 bandpass FIR digital filters Easy to Implement Easy to Implement No stability issues No stability issues Linear Phase – Can add coefficients for each filter to obtain one filter that performs like all the individual filters Linear Phase – Can add coefficients for each filter to obtain one filter that performs like all the individual filters

March 2003 Smart EQ 9 Equalizer

March 2003 Smart EQ 10 Equalizer

March 2003 Smart EQ 11 Useful Applications Hearing aids Hearing aids Consumer audio Consumer audio Musical instrument amplifiers Musical instrument amplifiers Computer soundcards Computer soundcards

March 2003 Smart EQ 12 Upgrades & Enhancements Real-time automatic mode select Real-time automatic mode select Calibration mode Calibration mode More enhanced user interface More enhanced user interface Graphic display of audio spectrum (input and output) on VGA monitor or LCD Graphic display of audio spectrum (input and output) on VGA monitor or LCD

Questions