README
Signal Processing
The Signal Processing Plots module is designed for plotting computed signals.
Install
npm install @signalprocessing/plots --save
Usage
@signalprocessing/windows module can be both imported as commonJS or ES module.
1. Create index.js
let fft = require("@signalprocessing/transforms").fft ;
let amplitudeSpectrum = require("@signalprocessing/plots").amplitudeSpectrum ;
//Sampling Rate
let Fs = 1500;
//Sampling Period
let T = 1 / Fs;
//Length of signal
let L = 1000;
//Time array
let t = Array.from({ length: L }, (x, i) => i * T);
//A signal containing a 30 Hz sinusoid of amplitude 0.5 and a 100 Hz sinusoid of amplitude 1.
let S = Array.from( t, (x, i) => 0.5 * Math.sin(2 * Math.PI * 30 * x) + Math.sin(2 * Math.PI * 100 * x));
//Compute the Fourier transform of the signal.
let [real, imag] = fft(S);
//Plot amplitude spectrum
amplitudeSpectrum(real, imag, Fs, "myDiv");
//myDiv is id of html div element to create plot chart on it.
- Create index.html and add index.js as script into your html file. Then create div element with id
myDiv
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>Document</title>
</head>
<body>
<div id="myDiv">
<!-- Plotly chart will be drawn inside this DIV -->
</div>
<script src="./index.js" charset="utf-8"></script>
</body>
</html>
- In Node, there is no browser window. So you should create a web server to serve your html file.
To simplify this step I am using Parcel and cross-env modules.
If you have already setup your http server, then you may skip these step.
However, I am strongly recommending you to use cross-env and Parcel to make your code works on different platforms.
Install and save these modules as development.
npm install --save-dev cross-env parcel-bundler
- Run the script below in the terminal to see results in the browser. In the first run, it will take a few minutes to build your files.
cross-env NODE_ENV=development parcel index.html --no-hmr --open
- Alternatively, you may also add scripts declaration into your package.json file
"scripts": {
"watch": "cross-env NODE_ENV=development parcel index.html --no-hmr --open "
},
- And then run the command below in working directory.
npm run watch
