Digital Processing of Audio Signals

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
13
(No Transcript)
14
Limitations

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

15
Alternate Approach
FIR Filter
16
(No Transcript)
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
Part Description Cost ()
U1 LM386 Audio Power Amplifier Chip 0.55
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
Bypass 100pf Ceramic Capacitor 0.10
R4 10? Resistor 0.15
C4 0.05?f Ceramic Capacitor 0.10
C3 220?f Electrolytic Capacitor 0.15
E3631A Triple Out DC Power Supply, HPIB/RS-232 1,122.00
BN2120 E-Series Multifunctional I/O DAQ 395.00
TOTAL 1518.75
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