Wavelet Signal Denoiser

Visualize and denoise time series data

Description

The Wavelet Signal Denoiser app is an interactive tool for visualizing and denoising real-valued 1-D signals and comparing results. With the app, you can:

• Access all the signals in the MATLAB^® workspace.

• Easily adjust default parameters and apply different denoising techniques.

• Visualize and compare results.

• Export denoised signals to your workspace.

• Recreate the denoised signal in your workspace by generating a MATLAB script.

The Wavelet Signal Denoiser app provides a way to work with multiple versions of denoised data simultaneously.

A typical workflow for denoising a signal and comparing results using the app is:

1. Start the app and import a 1-D signal from the MATLAB workspace. The app provides an initial denoised version of your data using default parameters.

2. Adjust the denoising parameters and produce multiple versions of the denoised signal.

3. Compare results and export the desired denoised signal to your workspace.

4. To apply the same denoising parameters to other signals in your workspace, generate a MATLAB script and modify it as you see fit.

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Open the Wavelet Signal Denoiser App

• MATLAB Toolstrip: On the Apps tab, under Signal Processing and Communications, click Wavelet Signal Denoiser .

• MATLAB command prompt: Enter waveletSignalDenoiser.

Examples

Denoise Signal Using Default Settings

This example shows how to denoise a 1-D signal using the app default settings.

Load the noisy Doppler signal.

load noisdopp

Start the Wavelet Signal Denoiser app by choosing it from the Apps tab on the MATLAB® Toolstrip. You can also start the app by typing waveletSignalDenoiser at the MATLAB command prompt.

Load the noisy Doppler signal from the workspace into the app by clicking Import in the toolstrip. From the list of workspace variables that can be loaded into the app, select noisdopp and click Import.

The app displays the original signal, noisdopp, the denoised signal, noisdopp1, and the coarse scale approximation, Approximation.

To toggle what plots are visible, you can:

• Click Signals ▼ in the toolstrip and use the drop-down menu to toggle the visibility of the original and approximation plots.

• Click individual signals in the plot legend.

Parameters

Wavelet — Wavelet family

sym (default) | bior | coif | db | fk

Wavelet family used to denoise the signal, specified as one of the following:

• sym — Symlets

• bior — Biorthogonal spline wavelets

• coif — Coiflets

• db — Daubechies wavelets

• fk — Fejér-Korovkin wavelets

For additional information, see wdenoise.

Method — Denoising method

Bayes (default) | BlockJS | FDR | Minimax | SURE | UniversalThreshold

Denoising method to apply, specified as one of the following:

• Bayes — Empirical Bayes

• BlockJS — Block James-Stein

• FDR — False Discovery Rate

• Minimax — Minimax Estimation

• SURE — Stein's Unbiased Risk Estimate

• UniversalThreshold — Universal Threshold

For additional information, see wdenoise.

Rule — Thresholding rule

Median (default) | Mean | Soft | Hard | James-Stein

Thresholding rule to use. Valid options depend on the denoising method.

• Block James-Stein — James-Stein

• Empirical Bayes — Median, Mean, Soft, Hard

• False Discovery Rate — Hard

• Minimax Estimation — Soft, Hard

• Stein's Unbiased Risk Estimate — Soft, Hard

• Universal Threshold —Soft, Hard

For additional information, see wdenoise.

Programmatic Use

waveletSignalDenoiser

waveletSignalDenoiser opens the Wavelet Signal Denoiser app. Once the app initializes, import a signal to denoise by clicking Import.

waveletSignalDenoiser(sig)

waveletSignalDenoiser(sig) opens the Wavelet Signal Denoiser app, and imports and denoises sig using wdenoise with default settings. The app plots sig, the denoised signal, and its coarse scale approximation.

sig is a variable in the workspace.

• sig can be a 1-by-N or N-by-1 real-valued vector.

• sig is double precision.

Tips

To denoise more than one signal simultaneously, you can run multiple instances of the Wavelet Signal Denoiser app.