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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

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

Videos from the Software Defined Radio Academy 2024 Conference Now On YouTube

Videos of talks from the Software Defined Radio Academy 2024 (SDRA'24) conference have recently been uploaded to YouTube. SDRA'24 was hosted primarily as an online conference but was also held physically at the German Friedrichshafen HAMRADIO conference in June 2024.

The talks are slowly being released on YouTube with eight talks released so far on their SDRA'24 playlist. Make sure you subscribe to their YouTube channel to be notified when more talks are released.

Some of the talks of interest that are released include:

  • FobosSDR by RigExpert
  • CW Bandwidth Optimization
  • DMR Tier III base station - TRX in software defined radio
  • High Res Propagation Measurements

You can find the titles of talks of videos that haven't been released yet on the SDRA'24 programme page. Some interesting yet to be released talks include:

  • High Resolution Propagation Measurements Using a WSPRSONDE-8 beacon and a RX888 SDR
  • GNU Radio Project Update
SDRA'24 - 01 - Welcome and Introduction

WarDragon: Real-Time Drone Remote ID Tracking with Snifflee, TAR1090 and ATAK

Over on YouTube Aaron, creator of DragonOS and the WarDragon kit has uploaded a video showing how he was able to detect drone Remote ID with a Bluetooth dongle and plot it on a TAK map. Remote ID is an RF system regulated in many countries that broadcasts drone information, including GPS position, often over Bluetooth Long Range or Wi-Fi. Note that the Bluetooth dongle is not an SDR, but this story may still be interesting for many readers.

The setup uses Sniffle, which is an open-source Bluetooth sniffer program for TI CC1352/CC26x2 based Bluetooth hardware. Sniffle passes sniffed data packets into SniffleToTak which is open-source software that relays the drone ID packets into a TAK server, which can then be viewed in TAK software like ATAK.

Aaron tests the setup with his DJI drone flying nearby, and shows that the drone is successfully detected and plotted on the TAK map. He also plots the positions of nearby aircraft received via a second ADS-B receiver to show that drones and aircraft can be plotted on the same map.

WarDragon Enhancing Drone Remote ID Real-Time Tracking + ADS-B w/ ATAK (TAR1090, Sniffle) Part 3

TechMinds: A Review of the RigExpert FobosSDR

Earlier this year the Ukrainian company RigExpert released the FobosSDR, and only recently has it become available to most people in the world via global resellers. FobosSDR is an RX-only USB 3.0 device, with a 100 kHz to 6 GHz tuning range, 50 MHz of bandwidth, and 14-bit ADC resolution. Current pricing from US resellers is US$395 and from EU resellers around 495,00 €.

Recently Matt from the TechMinds YouTube channel reviewed the FobosSDR, showing an unboxing, description and review of the hardware. Unfortunately, while the specs on paper look good, Matt notes that the FobosSDR does not perform well.

In the video, Matt starts by testing around the broadcast FM band and shows how the FobosSDR suffers from multiple mirrored signals, even with the gain settings turned right down. He notes that other similarly priced SDRs perform a lot better and that even an RTL-SDR performs better.

Matt then goes on to test the HF bands, noting that there is no gain control available on these bands and that there are also extreme levels of signal mirroring all across the HF band.

Unfortunately, we are starting to see other similar reports about poor performance from the FobosSDR. For example, on arcticdx's blog he also does not recommend the SDR [1][2],

RigExpert Fobos SDR 100KHz To 6GHz SDR Receiver

A Video Review of FobosSDR

Back in April of this year, we posted about the FobosSDR, an upcoming software defined radio product from the Ukrainian company RigExpert. FobosSDR is an RX-only USB 3.0 device, with a 100 kHz to 6 GHz tuning range, 50 MHz of bandwidth, and 14-bit ADC resolution. At the time of the previous post, FobosSDR was not yet for sale, but now we see that it is available from some European distributors with a price of 495,00 € (~US$544).

Recently 'Radio Bunker' has uploaded a video review of the FobosSDR on his YouTube channel. Note that the video is in Spanish, however, you can use the YouTube auto-translate function.

In the video, Radio Bunker unboxes the FobosSDR and explains its specs and features, then goes on to show how to install the drivers and get it up and running with SDR#. He then shows the SDR receiving some signals like broadcast AM, FM, shortwave, DAB, and WiFi in SDR# with 50 MHz bandwidth.

▶️ REVIEW: FOBOS SDR ◀️ UN RECEPTOR SDR DE GAMA ALTA

Pi Pico Rx: A Breadboard Software Defined Radio Based on the RP2040 Raspberry Pi Pico

Over on hackster.io we've seen a story about how maker Jon Dawson designed a self-contained software-defined radio based on the Raspberry Pi Pico that can receive 0 - 30 MHz, with up to 250 kHz of bandwidth. The Raspberry Pi Pico is a microcontroller board based on the Raspberry Pi Foundation's own RP2040 chip.

The Pi Pico Rx's front end consists of a Tayloe Quadrature Sampling Detector (QSD) mixer which makes use of the PIO (Programmable Input/Output) feature on the RP2040. The circuit also has an encoder knob for tuning and a small OLED screen.

Jon had originally created the Pi Pico Rx on a custom PCB, however, his latest work brings the cost down by showing that it can just as easily be implemented on a breadboard with through-hole components.

The full writeup can be found on Jon's blog "101 Things", as can the open source firmware. He has also uploaded a YouTube video explaining and demonstrating the project which we've embedded below.

Software Defined Radio with Pi-Pico

Tech Minds: A Beginners Guide to the Radioberry HF SDR Transceiver Pi Hat

Recently on the Tech Minds YouTube channel, Matt uploaded a video explaining how to set up and use the Radioberry HF SDR Transceiver Pi Hat. The Radioberry is an HF SDR transceiver based on the AD9866 chip. It has an operating frequency between 0 - 30 MHz, a 12-bit ADC, a maximum bandwidth of up to 384 kHz, and one RX and one TX channel. It is designed as a 'Pi hat' which means that it needs to be connected and sit on top of a Raspberry Pi single-board computer.

In his video Matt shows how to set up the Radioberry Raspberry Pi software. The process begins with installing the Raspbian OS, logging into SSH, and running the Radioberry installation script. He then shows how to connect to the Radioberry over a local network using SDR-Console V3. Later he shows how to install the pihpsdr software which gives the Radioberry a desktop control app that can be used with a LCD screen connected to the Raspberry Pi.

Matt goes on to show how he was also able to use the Radioberry TX function to make WSPR contacts across Europe from with his home location in the UK, despite its very low 150 mW output power.

The Beginners Guide To The Radioberry HF SDR Transceiver Pi Hat