Hackaday Supercon 2024: Microcontrollers Are Just Radios in Disguise

Thank you to RTL-SDR.COM reader David for letting us know about an excellent talk from Charles Lohr (@cnlohr) at the 2024 Hackaday Supercon about turning microcontrollers into radios by abusing their output GPIOs to create RF generators.

This talk explores ways to leverage every cycle of underpowered microcontrollers to get them doing the work of parts ten times their price, including operations normally done with dedicated radio hardware.

This is a concept we have seen quite often before in projects like RPiTX and Osmo-FL2K which turns a Raspberry Pi and cheap VGA adapter respectively, into an arbitrary RF signal transmitter with no transmit components required.

In his talk Charles Lohr takes this concept further, showing how almost any microcontroller like an ATTiny85, ESP8266, CH32v203, and ESP32-S2 can be turned into a transmitter. In the talk, Charles shows how he used the I2S bus on an ESP8266 to transmit NTSC color video to a TV and transmit LoRa via his LoLRa software. He then notes that he was able to use the ESP32-S2 to transmit LoRa over 2.5 miles away.

Finally, Charles shows how the CH32v203 microcontroller can also be used as a receiver. With some code he wrote he is able to display the received signal on an FFT computed directly on the CH32v203, and even have a web interface to tune to specific frequencies and playback AM audio.

Hackaday Supercon 2024 - Microcontrollers Are Just Radios in Disguise - Charles Lohr

CNLohr's own YouTube video on the topic is also an excellent overview.

How far can I broadcast LoRa packets WITHOUT a radio? - LoLRa

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NickStick Design Releases the RF PowerSnitch USB-C Version

Recently Majodi from NickStick Design wrote in and wanted to share with us some updates to the 'NickStick RF PowerSnitch' which we previously posted about in 2021. The PowerSnitch is a device that can be used to gain a quick insight into RF power levels. This is useful to help prevent exposing your expensive and sensitive RF equipment, like an SDR or VNA, to excessive power levels that could destroy it.

The device uses three LEDs to tell you the power level. Green means you have a safe power level, caution is yellow and danger is red. Yellow is set to around 0 dBm.

The RF PowerSnitch is available on Tindie or lectronz for US$29.50.

In a recent re-release, they replaced the micro USB port with a USB-C power port. They write:

Today, NickStick Design, an electronics design company for Makers, is excited to announce the launch of the RF Power Snitch USB-C, the newest version of its popular RF Power Snitch device. This updated model replaces the micro-USB port of the
original with a USB-C port, making it more versatile and future-proof for today’s connectivity needs.

“Our original RF Power Snitch saved many VNA devices from destructive power levels” Majodi of NickStick Design said. “With the RF Power Snitch USB-C, we’re excited to provide users with an upgrade which aligns with modern connectivity standards.

Over the years many more products in the RF domain became accessible to radio enthusiasts. RF Power Snitch is a valuable companion tool for checking the potentially destructive power of the signals one would want to feed to their equipment. Because, although tools like the TinySA, NanoVNA or SDR devices are extremely affordable today, for a maker it is still an investment worth protecting.

That’s why our goal was to develop a low-cost companion device that can help makers and experimenters (especially beginners) in the RF domain to gain insight in the power levels of a signal before hooking things up to their valuable test equipment. As an extra to this we also made it possible to attach an MCU for doing power readings and plotting.

Website: https://powersnitch.nickstick.nl

The RF PowerSnitch by NickStick Design
The RF PowerSnitch by NickStick Design
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SDR and RF Videos from DEFCON 32

Recently some videos from this year's DEFCON 32 conference have been uploaded to YouTube. DEFCON32 was held on August 8-11, 2024 at the Las Vegas Convention Center. DEFCON is a major yearly conference about information security, and some of the talks deal with wireless and SDR topics.

During the Defcon 32 wireless village, there were several interesting talks and the full playlist can be found here. The talks include introductions to software-defined radio, information about synthetic aperture radar laws, transmitting RF signals without a radio,  information about the allen radio telescope array, an introduction to the electronic warfare being used in Ukraine and much more.

Over on the DEFCON 32 main stage, there were also several interesting RF-related talks including:

  • RF Attacks on Aviation's Defense Against Mid-Air Collisions (Video)
  • Breaking the Beam:Exploiting VSAT Modems from Earth (Video)
  • GPS spoofing it's about time, not just position (Video)
  • MoWireless MoProblems: Modular Wireless Survey Sys. & Data Analytics (Video)
DEFCON32 Logo
DEFCON32 Logo
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SDRplay SDRconnect Preview 5 Released

At the beginning of November, SDRplay Released version 5 of their SDRconnect software. SDRconnect is a relatively new official software platform for the SDRplay line of devices. Unlike their other software, SDRUno, SDRconnect is multiplatform and comes with a cleaner interface.

In their latest 'Preview 5' build the team has added various features listed below. In addition, a week after Preview 5 was released, they also released 'Update 1' which fixed several bugs. You can read about the changes in their Release notes, or via the screenshot below.

SDR Connect Version 5 and Update 1 Release notes
SDR Connect Version 5 and Update 1 Release notes
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Using a HackRF and JavaScript Browser App to Perform Rolljam Replay Attacks on a Car

Over on her website, Charlie Gerard has uploaded a page showing how she was able to perform a replay attack on a car's wireless entry system using a HackRF and a JavaScript browser app she wrote.

Previously, Charlie had already written a JavaScript browser app for ADS-B tracking with an RTL-SDR. To achieve this she used the WebUSB API, which allows USB devices to connect to JavaScript apps in a web browser.

Having recently purchased a HackRF she wanted to see if something similar was possible with the HackRF. In her post, Charlie shows and explains the JavaScript code required to connect to the HackRF from a Chrome browser, and how settings like gain, frequency and sample rate can be adjusted. She then shows how to use the Canvas API to visualize the received data. Finally, she shows how to use the File System Web API to record data, and ultimately retransmit the recorded data with the HackRF.

The replay attack itself is based on the rolljam idea. She uses two HackRF's, with one sitting closer to the car's receiver and jamming it, and another recording the car's keyfob. This prevents the car from incrementing the keyfob's rolling code, allowing it to be recorded and used again at a later time.

Charlie has also posted a video of her tests, which we embedded below.

Hacking my friend's car using JavaScript

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Paper on Building a Low Cost RTL-SDR Based Hydrogen Line Radio Telescope

Back in 2020, we posted a tutorial on how to set up a low-cost Hydrogen Line radio telescope using an RTL-SDR, LNA, and WiFi grid antenna. Since then we have seen similar setups successfully replicated in the community many times.

In a recent Hackaday post, we discovered a paper by Jack Phelps who has written an in-depth technical and scientific description of his attempt at Hydrogen line radio astronomy with similar equipment. His paper goes into deeper scientific explanations and describes the experiment and hardware setup in detail including some signal processing, observation, and calibration equations that might be useful for those looking to understand the science more deeply. 

Jack Phelps Radio Astronomy Setup and some Results
Jack Phelps Radio Astronomy Setup and some Results
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Setting up an ADS-B Radar in a Vehicle Android Head Unit

Over on YouTube channel 'TAKEAPART' has uploaded a short video showing how he tracks aircraft via an RTL-SDR Blog V3 dongle and his car's Android head unit. The head unit is capable of running the ADS-B Radar App available on the Google Play store.

Once the app is installed, it's a simple matter of plugging in the RTL-SDR Blog V3 unit and running the app to start tracking aircraft.

How to ADS-B Radar in the CAR - Tracking Planes...

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A Video on Radar-TUI: A Terminal User Interface Based ADS-B Display

Back in 2022 we first posted about adsb_deku and radar-tui, a TUI (terminal user interface) for displaying ADS-B aircraft locations with an RTL-SDR receiver. A terminal user interface means that no desktop GUI is required, instead, the map and aircraft are drawn in the terminal window using just text characters.

adsb_deku and radar-tui are based on the open-source ratatui library. Recently, Orhun, one of the maintainers of ratatui wrote in and wanted to share a YouTube video he created demonstrating radar-tui in action. In the video, Orhun explains the RTL-SDR, shows how to set up radar-tui, and shows a demo of it in action.

If you're interested in this type of application, another similar terminal based ADS-B UI is coole-radar which we also posted about previosuly in 2019.

Terminal Tool of the Week: RADAR-TUI (View planes around you from the terminal!)

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