Signal Processing - Maple Help
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Signal Processing

 

 

Introduction

Application: Imaging a Speech Spectrogram

Application: Filtering Audio

See Also

Introduction

The new Signal Processing package in Maple 17 offers a suite of tools for frequency domain analysis, windowing, signal generation & analysis, and more. This document explores several applications of some of the functionality.

(1.1)

Application: Imaging a Speech Spectrogram

Import Wave File and Manipulate Data into Overlapping Slices

(2.1.1)

(2.1.2)

(2.1.3)

Slice the data into segments with 256 samples. Each slice has a 50% overlap with the previous slice (that is, each slice starts at the half-way point of the previous slice).

(2.1.4)

Calculate the Spectrogram Data

Filter the data, slice by slice.

 

Calculate FFT of time segment consecutively.

 

Calculate Power Spectrum of each slice consecutively.

 

Convert spectrum into decibels.

 

Strip out the repeated data.

(2.2.1)

The frequencies go from 0 to half the sampling rate. Hence the frequencies are in steps of (in Hz):

(2.2.2)

Scale the spectra so that the values are between 0 and 255.

(2.2.3)

(2.2.4)

 

Consecutive rows represent slices in time, while columns contain the spectra at each time.

Plot the Spectrogram and Waveform

Application: Filtering Audio

Import Speech Sample

(3.1.1)

Plot Waveform and Power Spectrum

(3.2.1)

(3.2.2)

 

Apply IIR Butterworth or Chebyshev Filter

Apply Filter

View Before and After Power Spectrum and Waveform

Apply FIR Filter

Apply Filter

View Before and After Power Spectrum and Waveform

 

See Also

 Signal Processing Package Overview


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