RTL-SDR With Only A Browser

March 23, 2025 by Al Williams 15 Comments

Surely by now you’ve at least heard of RTL-SDR — a software project that let’s cheap TV tuner dongles work as a software-defined radios. A number of projects and tools have spun off the original effort, but in his latest video, [Tech Minds] shows off a particularly unique take. It’s a Web browser-based radio application that uses WebUSB, so it doesn’t require the installation of any application software. You can see the program operating in the video below.

There are a few things you should know. First, you need the correct USB drivers for your RTL-SDR. Second, your browser must support WebUSB, of course. Practically, that means you need a Chromium-type browser. You may have to configure your system to allow raw access to the USB port, too.

Watching the video, you can see that it works quite well. According to the comments, it will work with a phone, too, which is an interesting idea. The actual Web application is available as open source. It isn’t going to compete with a full-fledged SDR program, but it looked surprisingly complete.

These devices have grown from a curiosity to a major part of radio hacking over the years. Firefox users can’t use WebUSB — well, not directly, anyway.

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Writing A GPS Receiver From Scratch

March 18, 2025 by Bryan Cockfield 21 Comments

GPS is an incredible piece of modern technology. Not only does it allow for locating objects precisely anywhere on the planet, but it also enables the turn-by-turn directions we take for granted these days — all without needing anything more than a radio receiver and some software to decode the signals constantly being sent down from space. [Chris] took that last bit bit as somewhat of a challenge and set off to write a software-defined GPS receiver from the ground up.

As GPS started as a military technology, the level of precision needed for things like turn-by-turn navigation wasn’t always available to civilians. The “coarse” positioning is only capable of accuracy within a few hundred meters so this legacy capability is the first thing that [Chris] tackles here. It is pretty fast, though, with the system able to resolve a location in 24 seconds from cold start and then displaying its information in a browser window. Everything in this build is done in Python as well, meaning that it’s a great starting point for investigating how GPS works and for building other projects from there.

The other thing that makes this project accessible is that the only other hardware needed besides a computer that runs Python is an RTL-SDR dongle. These inexpensive TV dongles ushered in a software-defined radio revolution about a decade ago when it was found that they could receive a wide array of radio signals beyond just TV.

Hacker Tools, Hacked Tools

December 14, 2024 by Elliot Williams 3 Comments

We just love a good DIY tool project, and more so when it’s something that we can actually use cobbled together from stuff in our closet, or hacked out of cheap “toys”. This week we saw both a superb Pi Pico-based logic analyzer and yet another software frontend for the RTL-SDR dongle, and they both had us thinking of how good we have it.

If you don’t already have a logic analyzer, or if you have one of those super-cheap 8-channel jobbies, it might be worth your while to check out the Pico firmware simply because it gets you 24 channels, which is more than you’ll ever need™. At the low price of $4, maybe a little more if you need to add level shifters to the circuit to allow for 5 V inputs, you could do a lot worse for less than the price of a fancy sweet coffee beverage.

And the RTL dongle; don’t get us started on this marvel of radio hacking. If you vaguely have interest in RF, it’s the most amazing bargain, and ever-improving software just keeps adding functionality. The post above adds HTML5 support for the RTL-SDR, allowing you to drive it with code you host on a web page, which makes the entire experience not only cheap, but painless. Talk about a gateway drug! If you don’t have an RTL-SDR, just go out and buy one. Trust me.

What both of these hacker tools have in common, of course, is good support by a bunch of free and open software that makes them do what they do. This software enables a very simple piece of hardware to carry out what used to be high-end lab equipment functions, for almost nothing. This has an amazing democratizing effect, and paves the way for the next generation of projects and hackers. I can’t think of a better way to spend $20.

Use Your RTL, In The Browser

December 13, 2024 by Jenny List 14 Comments

The web browser started life as a relatively simple hypertext reading application, but over the 30+ years since the first one displayed a simple CERN web page it has been extended to become the universal platform. It’s now powerful enough to run demanding applications, for example a full software-defined radio. [Jtarrio] proves this, with an application to use an RTL-SDR, in HTML5.

It’s a fork of a previous Google-Chrome-only FM receiver, using the HTML5 WebUSB API, and converted to TypeScript. You can try it out for yourself if you have a handy RTL dongle lying around, it provides an interface similar to the RTL apps you may be used to.

The Realtek digital TV chipset has been used as an SDR for well over a decade now, so we’re guessing most of you with an interest in radio will have one somewhere. The cheap ones are noisy and full of spurious peaks, but even so, they’re a bucket of fun. Now all that’s needed is the transmit equivalent using a cheap VGA adapter, and the whole radio equation could move into the browser.

Junk Box Build Helps Hams With SDR

November 20, 2024 by Dan Maloney 5 Comments

SDRs have been a game changer for radio hobbyists, but for ham radio applications, they often need a little help. That’s especially true of SDR dongles, which don’t have a lot of selectivity in the HF bands. But they’re so darn cheap and fun to play with, what’s a ham to do?

[VK3YE] has an answer, in the form of this homebrew software-defined radio (SDR) helper. It’s got a few features that make using a dongle like the RTL-SDR on the HF bands a little easier and a bit more pleasant. Construction is dead simple and based on what was in the junk bin and includes a potentiometer for attenuating stronger signals, a high-pass filter to tamp down stronger medium-wave broadcast stations, and a series-tuned LC circuit for each of the HF bands to provide some needed selectivity. Everything is wired together ugly-style in a metal enclosure, with a little jiggering needed to isolate the variable capacitor from ground.

The last two-thirds of the video below shows the helper in use on everything from the 11-meter (CB) band down to the AM bands. This would be a great addition to any ham’s SDR toolkit.

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Portable Multi-SDR Rig Keeps Your Radios Cool

September 3, 2024 by Tom Nardi 12 Comments

With as cheap and versatile as RTL-SDR devices are, it’s a good idea to have a couple of them on hand for some rainy day hacking. In fact, depending on what signals you’re trying to sniff out of the air, you may need multiple interfaces anyway. Once you’ve amassed this arsenal of software defined radios, you may find yourself needing a way to transport and deploy them. Luckily, [Jay Doscher] has you covered.

His latest creation, the SDR SOLO, is a modular system for mounting RTL-SDRs. Each dongle is encased in its own 3D printed frame, which not only protects it, but makes it easy to attach to the base unit. To keep the notoriously toasty radios cool, each frame has been designed to maximize airflow. You can even mount a pair of 80 mm fans to the bottom of the stack to really get the air moving. The current design is based around the RTL-SDR Blog V4, but could easily be adapted to your dongle of choice.

In addition to the row of SDR dongles, the rig also includes a powered USB hub. Each radio connects to the hub via a short USB cable, which means that you’ll only need a single USB cable running back to your computer. There’s also various mounts and adapters for attaching antennas to the system. Stick it all on the end of a tripod, and you’ve got a mobile radio monitoring system that’ll be the envy of the hackerspace.

As we’ve come to expect, [Jay] put a lot of thought and effort into the CAD side of this project. Largely made of 3D printed components, his projects often feature a rugged and professional look that really stands out.

Read Utility Meters Via SDR To Fill Out Smart Home Stats

July 30, 2024 by Donald Papp 21 Comments

[Jeff Sandberg] has put a fair bit of effort into adding solar and battery storage with associated smarts to his home, but his energy usage statistics were incomplete. His solution was to read data from the utility meter using RTL-SDR to fill in the blanks. The results are good so far, and there’s no reason similar readings for gas and water can’t also be done.

[Jeff] uses the open source home automation software Home Assistant which integrates nicely with his solar and battery backup system, but due to the way his house is wired, it’s only aware of about half of the energy usage in the house. For example, [Jeff]’s heavy appliances get their power directly from the power company and are not part of the solar and battery systems. This means that Home Assistant’s energy statistics are incomplete.

Fortunately, in the USA most smart meters broadcast their data in a manner that an economical software-defined radio like RTL-SDR can access. That provided [Jeff] with the data he needed to get a much more complete picture of his energy usage.

While getting data from utility meters is conceptually straightforward, actually implementing things in a way that integrated with his system took a bit more work. If you’re finding yourself in the same boat, be sure to look at [Jeff]’s documentation to get some ideas.