DSP Applications Assignment

Parametric Equalizer
Weighting: 30%
Outcomes Being Assessed
(d), (e), (f).
Introduction
Bi-quad filters have two poles and two zeros arranged in the Z-plane as shown in figure 1.

Figure 1. Bi-quad Filter

These filters are widely used in the audio industry because they can either amplify or attenuate certain frequency components in a

signal. If the Pole radius (R) is greater than the Zero radius (r) the filter will amplify components around the centre frequency and

if r is greater than R then the filter will attenuate components around the centre frequency.
A practical application of the bi-quad filter is in parametric equalizers, where the filter behaviour is specified using the

parameters: centre frequency, gain/attenuation and bandwidth (EQ or Q factor) – see figure 2.

Figure 2 Parametric Equalizer Controls
Commercial parametric equalizers commonly have a number of independent filters.

Tasks
1. Design bi-quad filters to meet the following specifications:

Centre Frequency Gain/Attenuation Q
Filter 1 500 Hz -10 dB 3.5
Filter 2 1000 Hz -10 dB 5
Filter 3 2000 Hz +10 dB 6
2. Simulate the filters independently and in combination with each other using a tool such as MATLAB in order to verify that they

perform as specified.
3. Represent the filters you design in the following formats:
• Z-transfer function.
• Z-Plane diagram.
• Signal flow-graph.
• Magnitude response.
• Difference equation.

4. Develop a Flowcode program to implement your EQ digital filter(s) on the dsPIC development boards, and evaluate EQ real-time

performance.
5. Record your assignment work in an logbook on Unilearn.
Your logbook should be presented in a standard format, e.g. Date/time, Objectives, Equipment, Procedure, Results, and Discussion.
Evidence of the simulation process (graphs, comment, etc.) should be included in your logbook.
Your logbook should include the DSP lab work for this assignment and will be marked with reference to the guidance notes provided at

the beginning of the course.

Note: You may use the file WHITENOISE.WAV located on Unilearn as the test signal for your filters.
6. Demonstrate your work in the Laboratory.

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