1. Digital Processing of Audio Signals Prasanna Vemuri Padma Parakala Rekha Vemuri

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

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

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

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

6. Development Strategy

7. Design Phase

8. Analog Audio Amplifier

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

10. Digital Filtering

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

12. Speaker

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

15. Alternate Approach FIR Filter

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

18. Cost Analysis PartDescriptionCost ($) U1LM386 Audio Power Amplifier Chip0.55 R1 10  Resistor 0.15 C1 220  f Electrolytic Capacitor 0.15 R2 1k  Resistor 0.15 C2 10  f Electrolytic Capacitor 0.10 R3 10k  Resistor 0.15 Bypass100pf Ceramic Capacitor0.10 R4 10  Resistor 0.15 C4 0.05  f Ceramic Capacitor 0.10 C3 220  f Electrolytic Capacitor 0.15 E3631ATriple Out DC Power Supply, HPIB/RS-2321,122.00 BN2120E-Series Multifunctional I/O DAQ395.00 TOTAL1518.75

19. Time Line

20. 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

21. For more information Visit us at: www.cas.unt.edu/~prasanna/ELET5330