Digital Processing of Audio Signals Prasanna Vemuri Padma

Digital Processing of Audio Signals Prasanna Vemuri Padma Parakala Rekha Vemuri

Presentation Outline • • Objective Product Idea Development strategy Design Phase Alternate Approach Cost Analysis Time line Conclusions

Objective • The main objective of this project is to design an audio amplifier and to process the output signal using digital filtering techniques

Product Idea? ? ? What can be done to reduce noise? Which process is more suitable?

Product Idea? ? ? What are the resources available to achieve the task? • Is the product idea feasible and within the economical constraints?

Development Strategy

Design Phase

Analog Audio Amplifier

Analog to Digital Conversion ADH 0 From Output of Audio Amplifier NI BNC 2120 DAQ Board

Digital Filtering

Digital to Analog Conversion DAC 0 To Speaker NI BNC 2120 DAQ Board

Speaker

Limitations • Hissing --- Lack of Precision equipment • Time lag – Scan time for acquiring and processing the data

Alternate Approach FIR Filter

Alternate Approach Contd. . • To eliminate time lag -- Using scan clock -- Using case structure • To eliminate hissing -- IIR Filter with Scaled Window

Cost Analysis Part Description Cost ($) U 1 LM 386 Audio Power Amplifier Chip 0. 55 R 1 10 Resistor 0. 15 C 1 220 f Electrolytic Capacitor 0. 15 R 2 1 k Resistor 0. 15 C 2 10 f Electrolytic Capacitor 0. 10 R 3 10 k Resistor 0. 15 Bypass 100 pf Ceramic Capacitor 0. 10 R 4 10 Resistor 0. 15 C 4 0. 05 f Ceramic Capacitor 0. 10 C 3 220 f Electrolytic Capacitor 0. 15 E 3631 A Triple Out DC Power Supply, HPIB/RS-232 1, 122. 00 BN 2120 E-Series Multifunctional I/O DAQ 395. 00 TOTAL 1518. 75

Time Line

Conclusions • Real time application of digital filtering is more efficient for the acquisitions at lower speeds • Waveform graph after filtering showed reduction in noise of the audio signal

For more information Visit us at: www. cas. unt. edu/~prasanna/ELET 5330