Tagged: LoRa

GridDown Secure Messenger: Using an SX1262 LoRa Radio as a Drone Scanner and Secure Messenger

Back in March, we posted about GridDown, an open-source Android tablet-based situational awareness system designed to operate without an internet connection, which uses sensors such as an RTL-SDR, a SARSAT receiver and an ESP32-S3/SX1262 LoRa radio.

Recently, GridDown developer Cameron wrote in again and shared with us that the LoRa firmware for GridDown has now been released as an open-source project called "GridDown Secure Messenger" (main website).

The project uses a LILYGO T-Deck CYPHER-M8K (an ESP32-S3 with SX1262, 2.8" display, keyboard, and GPS) to implement secure, encrypted off-grid text messaging, and it also doubles as a 900 MHz drone scanner, with the ability to decode drone Remote ID.

Cameron has also provided two YouTube shorts [1] [2], showing the firmware in action.

Example Renders of the GridDown Secure Messenger Running on a LILYGO T-Deck CYPHER-M8K.
Example Renders of the GridDown Secure Messenger Running on a LILYGO T-Deck CYPHER-M8K.

AI Disclaimer: The renders appear to have been AI-generated.

ESP32 Bit Pirate Updates: New LoRa and Meshtastic Analysis Features

Back in September 2025, we posted about the "ESP32 Bus Pirate" firmware, which transforms an ESP32-S3 into a multi-protocol debugging and hacking tool. We later covered an update in March 2026 that added waterfall displays, cellular modem support, and an external radio expander.

Although the ESP32 does not have true SDR capabilities, it can leverage its numerous built-in radio hardware components to achieve a range of interesting SDR-like features. Recently, "Geo," the creator of the ESP32 Bus Pirate, wrote in to share some recent firmware updates with us.

Geo notes that the project is now called "ESP32 Bit Pirate" and now includes LoRa/SX1262 support and Meshtastic analysis features.

ESP32 Bit Pirate can now transmit and receive LoRa packets, monitor RSSI, scan frequency activity, display a simple waterfall view and perform Channel Activity Detection. Radio parameters including frequency, bandwidth, spreading factor, coding rate, transmit power, preamble and sync word can be configured directly from the interface.

Packets can also be recorded to the ESP32 filesystem and replayed later together with their original radio configuration.

A dedicated Meshtastic analysis shell has also been added, allowing users to send, receive and inspect Meshtastic packets. The goal is not to replace a Meshtastic node, but to provide a debugging and experimentation interface for understanding and interacting with LoRa/Meshtastic traffic.

The latest update has also added new LoRa hardware support for the Heltec Vision Master T190 and Heltec WiFi LoRa 32 V4, a browser-based debugging ecosystem, a Python scripting lab, and a BPIO2 USB adapter mode.

The project is entirely open source, and the code can be found on their GitHub page.

ESP32 Bit Pirate LoRa Support Added
ESP32 Bit Pirate LoRa Support Added

NyxScope: A Windows Multi-Protocol SDR Decoder Program with Multiple Digital Native Decoders

WARNING: Multiple people have noted that this program is not working as expected and may be overly buggy.

Recently, we've learned about NyxScope, a multi-protocol SDR receiver program for Windows that comes with multiple native decoders built right into the software. Their own description describes this all-in-one program best:

You get spectrum and waterfall, multiple concurrent VFOs, trunked-radio following, digital voice, aviation and marine tracking, paging, ISM sensors, HD Radio, and transcription, in one binary.

NyxScope includes decoders for P25 Phase 1 and Phase 2 voice, EDACS and NXDN control channels, ADS-B, AIS, ACARS, POCSAG, FLEX, LoRa CSS PHY + LoRaWAN MAC, Morse, RDS, CTCSS/DCS, Iridium decoding (with voice), and also includes a signal classification tool, Bluetooth LE scanner, and Whisper voice-to-text transcriber. It also outsources decoding of other protocols to mature decoding software such as multimon-ng, rtl_433, dsd-neo, nrsc5, direwolf, dumpvdl2, dump978, rs41mod where required, noting that the outsourced decoders are bundled with the software, meaning no extra installation work is required.

The software supports RTL-SDR, HackRF, Airpsy, bladeRF, SDRplay, Fobos and PlutoSDR. It also supports using multiple SDRs used in parallel.

The software does not appear to be open source, but it is provided for free with a limitation of 3 concurrent VFOs and a limitation on recording, transcribing, and pager messages. A perpetual per-machine license for $89.95 can be purchased to lift these restrictions and add access to their FCC frequency lookup database.

AI-Disclaimer: While the developers have not noted any use of AI tools, we suspect that AI was used in the creation of this software.

NyxScope Screenshot Scanning the 800 MHz Band
NyxScope Screenshot Scanning the 800 MHz Band

GridDown: An Offline-First Situational Awareness Platform with RTL-SDR, SARSAT, Meshtastic

Thank you to Cameron from BlackAtlas LLC for submitting their project GridDown, which is an open source Android tablet-based situational awareness system designed to operate without an internet connection. At its core, it appears to be a tablet with custom software, and then you can add sensors such as an RTL-SDR for ADS-B+Remote ID, a SARSAT receiver, and a Meshtastic ESP32-S3+SX1262 device. A demonstration of the UI can be found at https://griddown.blackatlas.tech.

Cameron writes:

[GridDown is] an offline-first situational awareness platform built for emergency preparedness, field response, and tactical operations in infrastructure-degraded environments — designed to work when cell towers are down, internet is unavailable, and operators are fully off-grid.

The platform is a Progressive Web App (~120,000 lines of vanilla JavaScript, no frameworks) that runs on Samsung Galaxy tablets, laptops/PCs, and works completely offline after initial setup. It's built by BlackAtlas LLC and is available for trial at https://griddown.blackatlas.tech.

The system has many facets to it, including:

  • Encrypted voice and text messaging via an ESP32-S3 with SX1262 LoRa transceiver
  • Passive RF sensing with the ESP32-S3 and SX1262.
  • Three passive drone detection methods: WiFi fingerprinting, FAA Remote ID reception, and 900 MHz control/telemetry link detection
  • Automatic gunshot detection via a ES7210 quad-channel I2S microphone on the ESP32-S3.
  • Automatic RF jamming detection
  • SARSAT beacon receiver
  • SSTV Encode/Decode
  • Meshtastic integration
  • APRS via Bluetooth TNC
  • ADS-B reception
  • RadioCode gamma spectrometer integration
  • Offline maps

ADS-B detection is handled by a Raspberry Pi 5 running an RTL-SDR Blog V4 dongle. Cameron writes:

The Pi connects to the tablet's built-in WiFi hotspot (no internet required — the hotspot functions as a local network only), and a Node.js bridge reads aircraft data from readsb and subscribes to the Remote ID receiver's MQTT output, then serves a unified WebSocket and REST API to the tablet. GridDown renders aircraft and drone tracks as heading-rotated silhouette icons on its offline map with altitude labels, age-based alpha fade, and emergency squawk alerting (7500/7600/7700). A 10,000 mAh USB-C PD battery provides approximately 5 hours of field runtime for the Pi.

The full setup script, hub bridge, and hotspot connection scripts ship with the project.

The software is dual-licensed, with it being open source GPL v3 (note that the GitHub link appears to be broken - we have asked for clarification) for non-commercial use, or a commercial licence for hardware bundles and business deployments. 

Alternatively, BlackAtlas LLC is selling ready-to-use kits, with the core tablet coming in at $799. Other bundles include the Tablet + SARSAT receiver for $1,299, the Tablet + Meshtastic bundle for $1,299, and the Tablet + ADS-B/Remote ID bundle for $1,999.

The GridDown Web Interface
The GridDown Web Interface

TEMPEST-LoRa: Emitting LoRa Packets from VGA or HDMI Cables

University researchers from China have recently shown in a research paper that it is possible to maliciously cause a VGA or HDMI cable to emit LoRa compatible packets by simply displaying a full-screen image or video. This has potential security implications as a malicious program could be used to leak sensitive information over the air, completely bypassing any internet or air-gap security systems.

In the past, we have demonstrated that TEMPEST techniques can be used to spy on monitors and security cameras by analyzing the unintentional signals they emit. This research takes the idea a step further by determining what particular images need to be displayed to create a LoRa packet with data. 

In the paper, the researchers mention using either off-the-shelf LoRa devices or low-cost SDRs such as the HackRF to receive the packets. The advantage of the SDR method is that it allows for customization of the frequency and the use of LoRa-like packets, which can achieve even longer ranges and higher data rates. The team show that they were able to achieve a receive range of up to 132 meters and up to 180 kbps of data rate.

TEMPEST-LoRa Test Setup
TEMPEST-LoRa Test Setup
(Demo video) TEMPEST-LoRa: Cross-Technology Covert Communication

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

Tech Minds: Testing Meshtastic Compatible Lilygo LoRa Devices

In the latest video on the Tech Minds YouTube channel Matt tests out the Meshtastic software running on varius Lilygo LoRa devices. Meshtastic is software that can run on cheap LoRa hardware that enables off-grid mesh network based communications.

Being mesh network based means that there are no central repeaters, and instead each device can extend the range of the network by being a repeater itself. Meshtastic can run on various cheap 'Lilygo' branded LoRa devices that come in 433, 868 or 915 MHz license free frequencies depending on your regional band plan.

In his video Matt tests out various models in the Lilygo range, including a ESP32 based wrist watch and he also shows how to install the firmware on each using the online flasher.

Meshtastic Compatible Lilygo Lora Devices

Tech Minds: Demonstrating RTL_433 Running on ESP32 Devices

Earlier in the month we posted about how rtl_433 has been ported to ESP32 devices that are combined with CC1101 or SC127X transceiver chips, such as the low cost LILYGO LoRa 32 boards available on Aliexpress.

Over on YouTube Matt from the Tech Minds channel has uploaded a video showing how to set up rtl_433 on an ESP32 device, and how to set it up with a home automation service like Home Assistant, Node Red or OpenHAB via an MQTT broker.

RTL 433 ON ESP32 DEVICE - MQTT HOME ASSISTANT