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.

Printed Case Lets Pair Of RTL-SDRs Go Mobile

May 29, 2024 by Tom Nardi 25 Comments

We’ll admit to not fully knowing what [Jay Doscher] has planned for the pair of RTL-SDR Blog V4 software defined radios (SDRs) that are enclosed in the slick 3D printed enclosure he’s designed. But when has that ever stopped us from appreciating a nice design when we see one?

Inside the ventilated enclosure is the aforementioned pair of RTL-SDR Blog V4 (SDRs), as well as a StarTech USB hub that they’re plugged directly into. It seems like it wouldn’t take much to adapt this design to any other pair of USB gadgets, such as flash drives or WiFi adapters.

In fact, if they’re smaller than the RTL-SDR [Jay] has used here, you could probably get away with only needing to modify the one side panel of the case.

The simple modularity of the design, with two end pieces and the top and bottom plates, makes such modifications easy as you don’t need to reprint the whole thing if you just want a different antenna aperture. It also makes it easy to print without support material, and with just a few tweaks, looks like it could be adapted to use laser-cut panels for the sides. This would not only be faster than printing, but depending on the material, could make for a very stout enclosure.

We’ve covered several designs from [Jay] over the years, including a number of heavy-duty mobile “doomsday” computers that certainly fit in with this same design aesthetic. After all, why not face the end of the world with a little style?

Pi 5 And SDR Team Up For A Digital Scanner You Can Actually Afford

February 10, 2024 by Dan Maloney 29 Comments

Listening to police and fire calls used to be a pretty simple proposition: buy a scanner, punch in some frequencies — or if you’re old enough, buy the right crystals — and you’re off to the races. It was a pretty cheap and easy hobby, all things considered. But progress marches on, and with it came things like trunking radio and digital modulation, requiring ever more sophisticated scanners, often commanding eye-watering prices.

Having had enough of that, [Top DNG] decided to roll his own digital trunking scanner on the cheap. The first video below is a brief intro to the receiver based on the combination of an RTL-SDR dongle and a Raspberry Pi 5. The Pi is set up in headless mode and runs sdrtrunk, which monitors the control channels and frequency channels of trunking radio systems, as well as decoding the P25 digital modulation — as long as it’s not encrypted; don’t even get us started on that pet peeve. The receiver also sports a small HDMI touchscreen display, and everything can be powered over USB, so it should be pretty portable. The best part? Everything can be had for about $250, considerably cheaper than the $600 or so needed to get into a purpose-built digital trunking scanner — we’re looking at our Bearcat BCD996P2 right now and shedding a few tears.

The second video below has complete details and a walkthrough of a build, from start to finish. [Top DNG] notes that sdrtrunk runs the Pi pretty hard, so a heat sink and fan are a must. We’d probably go with an enclosure too, just to keep the SBC safe. A better antenna is a good idea, too, although it seems like [Top DNG] is in the thick of things in Los Angeles, where LAPD radio towers abound. The setup could probably support multiple SDR dongles, opening up a host of possibilities. It might even be nice to team this up with a Boondock Echo. We’ve had deep dives into trunking before if you want more details.

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