Tagged: rtl-sdr

Tech Minds: Testing Out A New Signals Intelligence Tool Called Intercept

Over on the Tech Minds YouTube channel, Matt has uploaded a video where he tests out 'Intercept', a new tool for RF signals intelligence with RTL-SDRs and other wireless devices. It is open source with code available on GitHub and can be installed on Linux and OSX devices.

Intercept is a tool that combines multiple external decoder tools into one easy-to-access web interface. It is capable of the following:

  • Pager Decoding - POCSAG/FLEX via rtl_fm + multimon-ng
  • 433MHz Sensors - Weather stations, TPMS, IoT devices via rtl_433
  • Aircraft Tracking - ADS-B via dump1090 with real-time map and radar
  • Listening Post - Frequency scanner with audio monitoring
  • Satellite Tracking - Pass prediction using TLE data
  • WiFi Scanning - Monitor mode reconnaissance via aircrack-ng
  • Bluetooth Scanning - Device discovery and tracker detection

We note that features like WiFi and Bluetooth scanning will require a separate WiFi and Bluetooth adapter to be connected. In terms of supported SDR hardware, Intercept supports RTL-SDRs, as well as any SDR supported by SoapySDR.

In the video Matt shows how to install Intercept, and shows it decoding data from the various supported signal types.

Intercept Radio Signals For Intelligence Gathering With An RTL SDR

Guglielmo FM and DAB Receiver Software Updated to Version 0.7

Thank you to Marco for letting us know that his Guglielmo software has recently been updated to Version 0.7.

Guglielmo is an FM and DAB receiver for Linux, Windows and MacOS. It supports all major SDRs, including RTL-SDR, Airspy, SDRplay, HackRF, and LimeSDR. It is designed to be easy to use for media users rather than hobbyist technical users.

Version 0.7 adds the following features:

  • Raspberry PI appimage
  • UI improvements
  • Basic skins support
  • Logo handling

The new Raspberry Pi appimage, and binaries for other platforms can be found on the GitHub Releases page. Just expand the "assets" tab.

Guglielmo: Screenshot of the DAB Interface

Mykola: A New Fast Multichannel Scanner Application for RTL-SDR, Airspy and HackRF

A new multichannel SDR scanner application called 'Mykola' has recently been released by a Ukrainian programmer with the same name as the application. A scanner application allows users to scan a much wider bandwidth than the SDR's instantaneous bandwidth, while automatically searching for active signals.

Mykola advertises extreme scanning speed abilities, adaptive noise floor, and simultaneous demodulation of 3 channels (20 in the paid pro version). It currently supports RTL-SDR, Airspy R2, and HackRF SDR devices. Some of the other features include automatic normalization of the noise floor, audio panning, and support for Windows and macOS.

The application is free, but a pro version will be available in the future, which enables additional features such as stored channel scanning, recording, voice activation, CTCSS/DCS decoder, SDR migration, channel editor, and a base channel set. The pro version is not yet available, and pricing has not been announced. 

Features of the Mykola Scanning Software
Features of the Mykola Scanning Software
Mykola Scanner Interface
Mykola Scanner Interface

SDRSharp Frequency Manager Python Application

Thank you to Argilli Marco (IU4HMY) for writing in and sharing with us his Python application called "SDR# Frequency Manager 1.0.1" for managing frequency lists in SDR#. SDR# is a popular free SDR program commonly used with RTL-SDR and Airspy dongles. Argilli writes:

SDR# Frequency Manager is a Python application designed to simplify the management and editing of frequency lists used by SDR#. The software allows you to open, edit, and save SDR# XML frequency files in a clear and structured interface.

The application is free but closed source and available on his website.

SDR# Frequency Manager Python Application

The Thought Emporium Explores IMSI Cell Phone Tracking and Other Advanced Cell Phone Attacks with Software Defined Radios

Over on YouTube, The Thought Emporium channel has uploaded a video outlining how mobile phones constantly leak unique IMSI identifiers over the air, making passive location tracking much easier than most people expect. While LTE and 5G improve security, older 2G and 3G protocols still expose permanent subscriber IDs that can be collected and linked to movement over time.

The video highlights how accessible this surveillance is. A cheap RTL-SDR USB dongle, basic antenna, and free software pre-installed on DragonOS are enough to passively collect IMSI numbers from nearby phones running on 3G. Once you know a person's unique IMSI number, you can easily track their movements if you have cheap radios monitoring the areas they frequent.

They also show how it's possible to use a more advanced TX-capable SDR like a USRP B210 to create a Stingray device, which is a fake cell-tower base station that you can force nearby cell phones to connect to. Once connected to the Stingray, all communications from your phone can be tapped. Finally, they discuss SS7 attacks, which, while difficult and/or expensive to gain access to the SS7 walled garden, can allow malicious actors to easily reroute security-related messages, such as 2-factor authentication.

The video finishes with potential defenses, including turning phones off when needed, forcing more secure LTE/5G-only connections, and using tools that detect fake cell towers. Privacy-focused mobile services that rotate identifiers are also discussed.

Recreating NSA Spy Tech Was WAY Too Easy

 

Building a P25 Police Scanner with an RTL-SDR Blog V3 and ZimaBoard 2

Over on YouTube, creator "MostlyBuilds" builds a networked digital police scanner using an RTL-SDR Blog V3 dongle and a compact x86 single-board computer called the ZimaBoard 2. The system receives over-the-air police radio signals, decodes digital P25 voice traffic, and turns it into an audio stream that can be listened to from any device on the home network, such as a phone, tablet, or computer.

The video walks through the hardware setup, ZimaBoard 2 features, and software configuration using ZimaOS and Docker. The open-source OP25 decoder handles the digital radio decoding, while containerized services stream the audio using Icecast and MediaMTX. MostlyBuilds also explains how to find local police frequencies, avoid encrypted channels, and verify signals using a handheld radio.

To make the stream more usable, a custom Python script inserts silence during gaps in transmissions, creating a continuous audio feed. Finally, MostlyBuilds ends the video by showing a small ESP32-based client prototype that plays the stream through a speaker, plus a breakdown of the full audio pipeline.

DIY Digital Police Scanner With ZimaBoard 2

RadioTranscriber: Real-Time Public Safety Radio Transcription with Whisper AI

Over in our new forums, user Nite has shared a new open-source project that he's created called RadioTranscriber, a real-time speech-to-text tool for public safety radio feeds using OpenAI’s Whisper large-v3 model. The idea is to take live scanner audio, such as authenticated streams from Broadcastify, and continuously turn it into readable text with minimal babysitting. The project grew out of earlier experiments with Radio Transcriptor, which we posted about back in June, but quickly evolved into a more robust, long-running setup with better audio conditioning and fewer of Whisper’s common hallucinations.

Under the hood, RadioTranscriber is a Python script that pulls in a live stream, cleans it up with filtering, normalization, and WebRTC VAD, then runs Whisper large-v3 with beam search for transcription. A set of custom “hallucination guards” strips out common junk text and replaces alert tones with simple markers, while daily log rotation and basic memory management let it run unattended for long periods, even on a modest CPU-only machine. Although it’s tuned to the author’s local dispatch style, the config and prompt are easy to adapt, and the full code is available on GitHub for anyone who wants to experiment or build on it.

How OpenAI's Whisper Works
How OpenAI's Whisper Works

Discovery Dish 1420 MHz Hydrogen Line Feed Tested with a WiFi Grid Dish

Thank you to Alex P for writing in and sharing with us his detailed evaluation of the Discovery Dish 1420 MHz hydrogen line feed when paired with a low-cost 1m WiFi grid dish. The goal was to see how well this near off-the-shelf setup performs as a hydrogen line radio telescope. The Discovery Dish feed integrates the dipole very close to the internal LNA and filters to minimize losses, uses a weather-sealed enclosure, and is built around a low-noise Qorvo QPL9547 amplifier, which has a very low noise figure at 1420 MHz.

Alex used 4NEC2 with a simple geometry approximation to analyze the beam pattern and also experimentally determined the optimal feed-to-dish spacing for the WiFi grid. The results show that the Discovery Dish feed significantly outperformed a more standard feed + external LNA setup.

Alex also shows how he uses aluminum foil, or conductive foam, to shield the feed from all signals during a background correction scan. Generally, for background correction scans, we recommend pointing towards a cold area of the sky (any area far away from the Milky Way with little to no hydrogen), but Alex prefers this method.

Discovery Dish 1420 MHz Hydrogen Line Feed Tested on a WiFi Grid Dish
Discovery Dish 1420 MHz Hydrogen Line Feed Tested on a WiFi Grid Dish