Skip to main content

Exploring Sub-GHz Radio With RTL-SDR and GQRX

Today I took a look at some hardware for working with sub-GHz radio transmissions, especially FM. All of which came in a previous HackerBoxes box. My favorite item was definitely the RTL-SDR dongle! I could play around with this thing for hours surfing the radio waves and listening to weird broadcasts. There's even a Python library named pyrtlsdr for working with these devices so you can scan/record radio transmissions programmatically: https://github.com/roger-/pyrtlsdr

Next I'm going to solder together the FM transceivers included in the box and play around with writing Arduino firmware for them. Those things should work similar to the LoRa modules I've been using but they trade in the long range for increased bandwidth. Should be good for streaming data locally and still have much better range than most home WiFi or Bluetooth.

Here's a video overview of the hardware included in HackerBox 0034 as well as a demo of the RTL-SDR dongle using GQRX to visually and audibly explore the radio waves.



The audio in my videos has also improved a bit since being sent this Purple Panda lapel microphone. If you do any audio recording with your laptop or phone this little mic is cheap and it definitely improves the quality over a builtin mic. [Not a sponsor, they did send this for free but it's also only $20. I really needed a mic.]

Popular posts from this blog

DIY Solar Powered LoRa Repeater (with Arduino)

In today's video I be built a solar powered LoRa signal repeater to extend the range of my LoRa network. This can easily be used as the basis for a LoRa mesh network with a bit of extra code and additional repeaters. Even if you're not into LoRa networks all of the solar power hardware in this video can be used for any off-the-grid electronics projects or IoT nodes!  

A Lesson in LoRa Module P2P Standards (or the Lack Thereof)

I got a handful of LoRa modules from Reyax a while back, the RYLR896 model based on Semtech SX1276 chips. Instead of using an SPI interface they operate over UART using a small set of AT commands. This made them easier to work with since I didn't have to dig too deeply into a bunch of SPI registers and Semtech specs and they communicate between one another really well. My Espruino JS module for them is available here , which I've used in a few of my YouTube videos. And more recently I've written a MicroPython module for them here .   (A pair of Reyax RYLR896  modules) But, always being on the lookout for different boards and platforms I eventually ended up with a few Maduino LoRa boards. These are cool because they have an Arduino-compatible ATmega328 and the same Semtech LoRa chip (via an RFM95) both integrated on one board. They weren't compatible with Espruino or MicroPython though, and they used the SPI interface instead of AT commands so I knew I would need to lo

Always Secure Your localhost Servers

Recently I was surprised to learn that web browsers allow any site you visit to make requests to resources on localhost (and that they will happily allow unreported mixed-content ). If you'd like to test this out, run an HTTP server on port 8080 (for instance with python -m http.server 8080 ) and then visit this page. You should see "Found: HTTP (8080)" listed and that's because the Javascript on that page made an HTTP GET request to your local server to determine that it was running. Chances are it detected other services as well (for instance if you run Tor or Keybase locally). There are two implications from this that follow: Website owners could potentially use this to collect information about what popular services are running on your local network. Malicious actors could use this to exploit vulnerabilities in those services. Requests made this way are limited in certain ways since they're considered opaque , meaning that the web page isn't able