# NHE2404 DSP Applications:designing a Parametric Equalizer

NHE2404 DSP Applications:designing a Parametric Equalizer

# NHE2404 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**

- 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 |

- 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.
- Represent the filters you design in the following formats:

- Z-transfer function.
- Z-Plane diagram.
- Signal flow-graph.
- Magnitude response.
- Difference equation.

- Develop a Flowcode program to implement your EQ digital filter(s) on the dsPIC development boards, and evaluate EQ real-time performance.
- Record your assignment work in an logbook on Unilearn.

**Note:**You may use the file

**WHITENOISE**

**.WAV**located on Unilearn as the test signal for your filters.

- Demonstrate your work in the Laboratory.