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(8.D.2.7) IIRDecimator

Owned by Sam Stuart
Aug 14, 2024
1 min read

Overview

Audio sample decimator with IIR filter

Discussion

The IIR decimator module implements an IIR low-pass filter followed by a downsampler. The IIR filter is implemented as an 8th order elliptical filter. The module variable cutoffFreq must be smaller than Fs*0.5/D, where Fs is the sampling rate and D is the decimation factor.

  • This module accepts any input block size. 

  • The output block size equals the input block size divided by the decimation factor D.

  • The output sample rate equals the input sample rate divided by D.

Type Definition

-Not Shown-

Variables

Properties

Name

Type

Usage

isHidden

Default value

Range

Units

cutoffFreq

float

parameter

0

10800

20:24000

Hz

Rs

float

parameter

0

60

10:100

dB

D

int

const

0

2

Unrestricted

 

Pins

Input Pins

Name: in

Description: Audio input

Data type: float

Channel range: Unrestricted

Block size range: Unrestricted

Sample rate range: Unrestricted

Complex support: Real

Output Pins

Name: out

Description: Audio input

Data type: float

Scratch Pins

Channel count: 1

Block size: 32

Sample rate: 48000

 

Channel count: 1

Block size: 32

Sample rate: 48000

 

Channel count: 1

Block size: 32

Sample rate: 48000

MATLAB Usage

File Name: iir_decimator_subsystem.m

SYS=iir_decimator_subsystem(NAME, D) Create a sub-system that decimates audio samples with IIR filter(s). IIR filters are implemented with allpass_pair sub-system with Elliptic filter option. Arguments: NAME - name of the module. D - Decimation factor. Copyright 2018. DSP Concepts, Inc. All Rights Reserved. Author: Taka Unno

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