Overview

Variable slope tilt filter

Discussion

This subsystem implements a filter with the desired slope over the specified band. The intended application is for filtering white noise to produce noise of a desired color. Common noise colors include Violet, Blue, White, Pink, and Red, with respective slopes of +6, +3, 0, -3, and -6 dB/octave. Arbitrary slopes, such as -7.15 dB/octave can also be used. fStart specifies the frequency at which the slope begins, while fStop specifies the frequency at which the slope ends. avgPower specifies the squared 2-norm of the filter. This is used to preserve the area under the frequency response curve, regardless of the desired slope. The underlying filter is implemented as a cascade of biquad stages. The default number of stages is set to 3, allowing for slopes ranging from -18 to +18 dB/octave. The number of biquad stages can be adjusted by right-clicking the Tilt Filter module in Audio Weaver Designer and selecting the "Module Name and Arguments..." option.

Type Definition

-Not Shown-

Variables

Properties

Pins

Input Pins

Name: in

Description:

Data type: float

Channel range: Unrestricted

Block size range: Unrestricted

Sample rate range: Unrestricted

Complex support: Real

Output Pins

Name: out

Description:

Data type: float

Scratch Pins

Channel count: 1

Block size: 32

Sample rate: 48000

MATLAB Usage

File Name: tilt_filter_subsystem.m

 SYS = tilt_filter_subsystem(NAME, NUM_STAGES)
 Implements a tilt filter which attenuates frequencies based on a specifed
 slope in dB/octave.  Arguments:
    NAME - name of the module.
    NUM_STAGES - number of Biquad stages used internally.  By default this
                 equals 3.