Category: Other

V2X2MAP: Visualize European 5.9 GHz V2X Vehicle and Traffic Signal Messages with an Android App and ESP32

Thank you to Peter for writing in and sharing news about his Android app called V2X2MAP, which makes Vehicle-to-Everything (V2X) radio traffic visible on a live map via an attached ESP32 board. The app is not free but costs only a small US$2.49 fee.

V2X is a cooperative wireless system in which vehicles and roadside infrastructure continuously broadcast small messages in the 5.9 GHz band. Equipped cars broadcast their position, speed, heading, and brake status about 10 times per second, while traffic signals broadcast their phase and timing, lane geometry, and event-driven hazard warnings. It can be thought of as something like ADS-B or AIS for cars, though at a much shorter range (typically a couple of hundred meters), with the added feature that roadside infrastructure also transmits.

V2X is designed to enhance vehicle safety, allowing vehicles to know about obstacles, traffic phases, and road geometry in advance. Currently, two incompatible standards are used: the older DSRC (Wi-Fi-based) and the newer C-V2X (cellular-based). Most markets are moving towards C-V2X because it provides short and long-range communications.

The V2X2MAP Android app works together with a $20 Waveshare ESP32-C5 board, which has an onboard 5.9 GHz WiFi 6 radio. The ESP32 receives the older Wi-Fi DSRC signals, particularly the ITS-G5 standard, which appears to be used only in Europe. Once running, V2X2MAP and the ESP32 decode the surrounding V2X broadcasts and plot live vehicles, hazard warnings, and traffic-light countdowns on a map of your immediate area.

V2X2MAP Screenshots
V2X2MAP Screenshots

Receiving ADS-B With a Semtech LR2021 LoRa Chip

Over on his blog, Zoltán Papp and team have created an interesting write-up investigating whether Semtech's LR2021, one of the latest LoRa transceiver chips, which draws only 10.4 mA at 3.3V, can be used as a single-chip ADS-B receiver at 1090 MHz. The LR2021 natively supports OOK modulation, and the datasheet even hints at ADS-B reception. Building on prior work, the team captured live ADS-B signals with an SDR and replayed them into the LR2021 eval board for repeatable bench testing.

The initial 3 MHz Rx bandwidth configuration had only a 50% packet success rate with no reception above -50 dBm, because the AGC could not settle within the short 8 us preamble. Extending the sync pattern into the Mode S 'df' field enabled reception across the full dynamic range, but at the trade-off of broadcast message reception only. Manchester decoding and CRC also had to be moved to the host, since, for an unknown reason, Manchester decoding with inverse polarity would not work on the chip.

Measured sensitivity came in about 5 dB shy of the theoretical -89 dBm, with most of the gap blamed on the eval board's front end being matched for 868 MHz rather than 1090 MHz. The team notes that with a modified front end, the theoretical sensitivity should be possible.

With the rise in Raspberry Pi costs due to the consumer memory chip crisis, cheaper ADS-B receiver hardware is welcome. Some existing microcontroller-based ADS-B decoders that we've seen recently include ADSBee and PicoADSB.

Signal Hound SDR Hardware used to Capture and Replay ADS-B For Testing
Signal Hound SDR Hardware used to Capture and Replay ADS-B For Testing

RPITX-UI: A Modernized, Easier to Use Fork of the RPITX Raspberry Pi Transmitter Software

Thank you to Ihar Yatsevich for writing in about his release of rpitx-ui, a modernized fork of F5OEO's popular rpitx project. If you were unaware, rpitx is software that turns a Raspberry Pi (most Pi hardware apart from the Pi 5 is supported) into a low cost RF transmitter by generating signals directly on a GPIO pin, requiring no extra hardware beyond a wire antenna. Ihar writes:

rpitx-ui started as a fork of F5OEO’s rpitx and has evolved into a modernized, easier-to-use version of the original Raspberry Pi RF transmitter project. The goal is to make rpitx easier to build, install, use, and extend on modern Raspberry Pi OS systems.

In rpitx-ui, the build system has been migrated to CMake, the project installs system-wide, and it has been adapted for 64-bit Raspberry Pi OS (Debian Trixie). Most transmitter binaries have been rewritten in modern C++20 with shared DSP, audio, and CLI libraries. SSB and AM now use an internal DSP chain with direct DMA output instead of shell pipelines (removing the large SSB startup delay), NFM is a standalone transmitter with wide/narrow deviation presets, WFM with RDS has configurable PI, PS, RadioText and 50/75 us pre-emphasis, CW/Morse has safer parsing with adjustable WPM, and a new RFgen mode supports noise, sweep, and multitone generation. Audio modes also now accept any libsndfile compatible format rather than only WAV.

The UI itself has been improved with file selection for common modes, loop or once playback, custom messages for POCSAG/RTTY/CW, Opera call sign input, SSB sideband selection, NFM deviation selection, and RDS parameter setup. Full source and build instructions can be found on the rpitx-ui GitHub page.

PicoADSB: An Ultra-Compact All-in-One ADS-B Receiver Now on Kickstarter

Over on Kickstarter, Lambda58 LLC has released a campaign for their PicoADSB product, a self-contained 1090 MHz ADS-B receiver that replaces a typical SDR plus Raspberry Pi feeder setup with a single SD-card-sized PCB measuring 25mm x 15mm and weighing only 3 grams. At the time of this post, the campaign has reached around $12,700 against a $10,000 goal, and closes on May 16. The maximum claimed reception range is 500km+. At this time, there is no support for 978 MHz UAT, though they mention staying tuned for updates.

A photo of the board shows that it is based on an ESP32-C3-Mini-1 for the WiFi web server, and on what appears to be a separate microcontroller and an L-band tuner chip. The antenna input is fed via a U.FL connector to a 1090 MHz SAW filter, an LNA, and then the tuner. We suspect that the microcontroller is used for its ADC and for ADS-B demodulation. 

PicoADSB appears to compete with ADSBee, which we previously covered. ADSBee is based on the Raspberry Pi Pico chip. However, ADSBee supports both 1090 MHz and 978 MHz on the same board, but costs a little more at US$152 for a set.

PicoADSB with SDCard for Comparison
PicoADSB with SDCard for Comparison

SPECTRAL-GSM: A Web-Based GSM Interception Platform Built on OsmocomBB

OsmocomBB is an open-source project that replaces the stock baseband firmware on old Motorola phones (C118, C139, etc.) that use the Texas Instruments Calypso chipset. By flashing custom "layer23" firmware over serial, these cheap legacy handsets become capable of accessing raw GSM radio data at the baseband level, enabling cell scanning, burst capture, and passive subscriber identity harvesting.

SPECTRAL-GSM builds on this by wrapping OsmocomBB into a full GSM intelligence suite controlled from a single browser tab. The system supports up to five phones simultaneously and provides a structured pipeline: scan local GSM cells, capture raw bursts on a target channel, crack the A5/1 encryption using rainbow tables on a 2 TB SSD, and then use the recovered session key for real-time voice and SMS decryption. Additional modules handle passive IMSI catching, targeted single-IMSI surveillance, silent SMS location probing via a USB modem, and OpenCellID cell tower mapping.

The developer notes that the platform is intended for authorized research, law enforcement, and educational use. At the moment, Mini0com has not provided a link or website to the software, only providing a PDF file, and video demonstrations of the system on their YouTube channel. Contact details for Mini0com can be found in the description on the YouTube videos below.

Spectral-GSM OsmocomBB

OTP Capture Demonstration Using Spectral-GSM OsmocomBB

TRNXSDR-Carrier: A Modular Baseboard for SDR Modules

Over on GitHub, user acruxcz has released the TRNXSDR-carrier, an open hardware baseboard platform designed to host and interconnect multiple SDR modules. The board is built around a Xilinx XC7Z015 FPGA with 1 GB of DDR3 RAM at 1066 MHz, and features four SMA RF connectors, Gigabit Ethernet, an SFP optical port (with GTX support planned for up to 5 Gbit throughput), and USB-C with Power Delivery. It is not a standalone SDR, instead it acts as a central hub that requires external SDR modules connected via its expansion slots.

The slot system is a defining feature. The baseboard provides two high-speed primary slots (one with JESD204B support via GTX), two lower-speed primary slots, and room for an expansion board adding a further six slots and ten module positions in total. Planned RF modules include Lime Microsystems LMS6002D and LMS7002M chips, as well as Analog Devices AD9361/AD9363/AD9364 transceivers. A custom GNU Radio OOT source block is already functional, and initial RX testing at 433 MHz shows a clean signal with minimal noise floor. SoapySDR driver support, which would bring compatibility with SDR++, SDRangel, and other tools, is planned.

The hardware design is at Rev 1.0 with a Rev 2.0 in progress to address known bugs. The project is actively under development. It is not yet known if the developers plan to sell hardware, or leave it as open-source plans. 

The TRNXSDR-Carrier Board
The TRNXSDR-Carrier Board

PhaseLatch: Using a 1970’s Microprocessor Chip with a Modern 20 MSPS ADC

Back in September 2025 we posted about Anders Nielsen's PhaseLoom, an SDR based on the MOS Technology 6502 chip - the chip behind the early age of home computing, powering iconic systems like the Apple I & II, Commodore 64, Atari, and Nintendo Entertainment System.

Anders has now moved on and created PhaseLatch, which combines the 6502 with a modern ADC that can be memory-mapped directly onto the 6502's data bus. Although achieving the theoretical max ADC bandwidth of 20 MSPS is not possible with the underpowered 6502, Ander's notes that when combined with some external RAM he was still able to perform some DSP on the 6502 such as tone detection.

The entire project is open source on GitHub, and Anders sells pre-made boards for experimentation.

6502 SDR with 20MHz ADC!

Integrive-100: A Standalone MIMO SDR for Real-Time Precision

Thank you to Jayoung from HTWAVE for submitting news about the upcoming crowdfunding campaign for their "Integrive-100" software-defined radio. The Integrive-100 is an AD9361 based SDR with 70 MHz – 6 GHz tuning range, 2x2 MIMO TX/RX channels and up to 56 MHz bandwidth per channel.

They note a defining feature is a pre-built and validated FPGA-based PHY baseline with API access, allowing researchers to skip the basic infrastructure development steps and move straight to developing onboard DSP algorithms on the AMD Zynq-7020 FPGA/ARM CPU.

They write:

SDRs have long served as flexible testbeds for wireless communication research. Their ability to define functions through software makes them ideal for rapid prototyping. However, many SDRs struggle with non-deterministic latency caused by relying on a host PC for real-time signal processing where samples must traverse a communication interface and be handled by a non-real-time OS. This makes it difficult to accurately measure real-time performance, a fundamental requirement for 5G/6G research. This challenge is exactly why we decided to build our own SDR from the ground up.

By leveraging FPGA acceleration, we offloaded real-time signal processing entirely to the board, eliminating host PC dependency. While PC connectivity remains an option for monitoring and logging, the critical signal processing is handled on-board, ensuring that jitter is minimized and allowing you to test your algorithms in the most precise environment possible. Furthermore, by integrating an ARM processor and Embedded Linux, we’ve enabled high-level resource management and seamless compatibility with existing SDR software stacks.

In MIMO environments or scenarios involving high mobility, phase noise and phase synchronization are significant hurdles. Since our goal was industrial-grade deployment, we focused intensely on phase coherence. Unlike low-quality oscillators that degrade RF signal quality, we utilized high-performance components to achieve ultra-low phase noise and synchronized dual oscillators to ensure inter-channel phase consistency.

The best indicator of this stability is our OFDM 256-QAM constellation, which demonstrates the superior phase stability and synchronization our platform can achieve. Furthermore, our real-time video streaming demo, successfully transmitting high-throughput data with zero errors, stands as a testament to the integrity of our synchronization and phase noise control.

Finally, we provide robust API access (C, C++, Python), allowing users to control the system through simple function calls without needing deep FPGA expertise. By supporting standard software frameworks, researchers can easily port their existing projects to our hardware. Our goal is to eliminate the days or weeks spent on infrastructure setup. We want you to achieve productivity from Day 1.

HTWAVE MIMO SDR Video transmission

Left: Integrive-100, Right: OFDM 256-QAM constellation Stability Demo
Left: Integrive-100, Right: OFDM 256-QAM constellation phase stability demo