sandeepmistry / rtlsdrjs

📡 Turn your Realtek RTL2832U based device into an SDR receiver using JavaScript

📡 rtlsdr.js

Turn your Realtek RTL2832U based device into an SDR (Software Defined Radio) receiver using JavaScript.

Supports Node.js and WebUSB compatible browsers.

Requirements

Hardware

• Realtek RTL2832U based USB adapter with R820T tuner chip

Software

• Node.js 8.x or later + node-usb requirements
• Web browser that supports WebUSB

Setup

Node.js

Install: npm i rtlsdrjs

Require: const RtlSdr = require('rtlsdrjs');

Browser

Download a rtlsdr.js build from a release.

Include rtlsdr.js in you HTML page: <script src="path/of/rtlsdr.js"></script>

Usage

let readSamples = true;

async function start() {
  //
  // request a device
  // - displays prompt in browser
  // - selects first device in Node.js
  //
  // RtlSdr.getDevices() can be used to get a list of all RTL SDR's attached to system
  //
  const sdr = await RtlSdr.requestDevice();

  //
  // open the device
  //
  // supported options are:
  // - ppm: frequency correction factor, in parts per million (defaults to 0)
  // - gain: optional gain in dB, auto gain is used if not specified
  //
  await sdr.open({
    ppm: 0.5
  });

  //
  // set sample rate and center frequency in Hz
  // - returns the actual values set
  //
  const actualSampleRate = await sdr.setSampleRate(2000000);
  const actualCenterFrequency = await sdr.setCenterFrequency(1090000000);

  //
  // reset the buffer
  //
  await sdr.resetBuffer();

  while (readSamples) {
    //
    // read some samples
    // - returns an ArrayBuffer with the specified number of samples,
    //   data is interleaved in IQ format
    //
    const samples = await sdr.readSamples(16 * 16384);

    //
    // process the samples ...
    //
  }
}

Acknowledgements

This library is based on Jacobo Tarrío's (@jtarrio) work in Google's Radio Receiver Chrome app, which used work from the RTL-SDR project. The Chrome USB API layer has been replaced with node-usb on Node.js and WebUSB when running in the browser.

License

Apache 2.0

rtlsdrjs's Issues

(Dumb) question

First of all, thank you for such an awesome library!

i have a question that's probably dumb, since i'm just dipping my feet to SDR world here. I ask it anyway.

I'm wondering what the data actually is that's coming out? Is it for only single frequency, or maybe frequency range somehow?

I would like to create sort of a scanner to show which frequencies have data. How could i do that? I mean from the current data how can i know which frequency range is it, to be able to compose wide spectrum of frequencies?

Documentation for front end

The current documentation doesn't give a good method to load the library.

I have tried a few methods, but here is the current use case I am unable to get working... I am trying to serve up the library from an isolated virtual machine and let the client alone load the RTL-SDR device. In other words, the dongle is NOT connected to the system running nodejs.

Error on the client:

Uncaught ReferenceError: require is not defined
    at browser.js:1

express application loader

const RtlSdr = require('rtlsdrjs');
const express = require('express')
const app = express()
const port = 9943

/* The folder structure
public/
 |_ rtlsdjs/
 |      |_ lib/
 |_____ browser.js
 |_ index.html
 */
app.use(express.static('public'))

app.listen(port, () => {
  console.log(`Example app listening at http://localhost:${port}`)
})

The web content...

<script src="rtlsdrjs/browser.js"></script>
<script>
let readSamples = true;

async function start() {
  //
  // request a device
  // - displays prompt in browser
  // - selects first device in Node.js
  //
  // RtlSdr.getDevices() can be used to get a list of all RTL SDR's attached to system
  //
  const sdr = await RtlSdr.requestDevice();

  //
  // open the device
  //
  // supported options are:
  // - ppm: frequency correction factor, in parts per million (defaults to 0)
  // - gain: optional gain in dB, auto gain is used if not specified
  //
  await sdr.open({
    ppm: 0.5
  });

  //
  // set sample rate and center frequency in Hz
  // - returns the actual values set
  //
  const actualSampleRate = await sdr.setSampleRate(2000000);
  const actualCenterFrequency = await sdr.setCenterFrequency(1090000000);

  //
  // reset the buffer
  //
  await sdr.resetBuffer();

  while (readSamples) {
    //
    // read some samples
    // - returns an ArrayBuffer with the specified number of samples,
    //   data is interleaved in IQ format
    //
    const samples = await sdr.readSamples(16 * 16384);

    //
    // process the samples ...
    //
  }
}
</script>

[Error: LIBUSB_ERROR_BUSY] { errno: -6 }

what is it?