Category: RTL-SDR

Iridium-Sniffer: A Standalone Iridium Satellite Burst Detector and Demodulator

Thank you to Aaron, who is most well known for creating the DragonOS distribution, for writing in and sharing with us a new open-source program he's recently released over on GitHub.

The program is called 'Iridium-Sniffer', and it is a standalone Iridium satellite burst detector and demodulator written in C. Typically, gr-iridium has been used for Iridium demodulation in the past, but it can be clunky and slow on lower-power embedded systems like the Raspberry Pi, as it requires the large GNU Radio dependency.

The program is compatible with iridium-toolkit, which performs the actual decoding and analysis of the Iridium packets demodulated by iridium-sniffer.

If you're not familiar with it, Iridium is a large global communications satellite constellation that provides services such as voice, messaging, and data. An antenna like our RTL-SDR Blog Active Patch antenna, combined with an SDR, can be used to receive these signals. Some data on Iridium is encrypted, but there is some unencrypted data that can be decoded when combining tools like iridium-sniffer and iridium-toolkit.

Iridium-sniffer is compatible with the HackRF, BladeRF, USRP (UHD), and SoapySDR (which includes RTL-SDR). Note that higher-bandwidth SDRs can receive much more of the ~30 MHz Iridium band, and therefore decode more data at once.

The Iridium Satellite Constellation
The Iridium Satellite Constellation

Multimon Pager Decoding on Android

Sarah (aka SignalsEverywhere) has recently released another open-source Android app that enables the multi-signal decoder Multimon-ng to be used on Android. Multimon-ng is a commonly used decoding app, that supports various protocols such as POCSAG/FLEX pagers, as well as DTMF, ZVEI, EAS and more.

The app requires the SDR++ Android app to be running in the background with an SDR like an RTL-SDR connected. The role of SDR++ is to receive the signal and send the demodulated audio over a network connection to the Multimon-NG app, which performs the final decoding.

The app APK can be downloaded from Sarah's website via a minimum $0 donation, or alternatively, built and installed from source.

Multimon-ng on Android!

Pocket 25: An Android P25 Phase 1 Digital Voice Radio Decoder

Thank you to reader "EN53" for submitting news about a newly released open source Android app called Pocket 25. Pocket 25 is an Android-based APCO Project 25 (P25) phase 1 digital voice decoder based on the DSD-Neo decoder engine. It was developed by Sarah Rose (aka SignalsEverywhere), whose other software we have posted about in the past.

APCO P25 phase 1 trunked digital voice systems are commonly used in the United States, Canada, Australia, and other countries by emergency services. As long as the P25 network is unencrypted, it is commonly decoded to audio with an RTL-SDR and decoding software such as DSDPlus or SDRTrunk.

Pocket 25 allows users to now decode P25 signals on portable Android devices. An RTL-SDR can be connected to an Android device via a USB-OTG cable, or a remote networked RTL-SDR can be used via an rtl_tcp connection. The app also supports RadioReference accounts, automatic GPS site hopping, smart filtering, and logging.

In the readme, Sarah also notes that, because Pocket 25 is based on the DSD-Neo engine, it supports additional digital voice protocols, including DMR, NXDN, and others. However, the interface is designed around P25, so non-P25 systems may show incorrect metadata.

The software is open source and code can be found on the GitHub. There is also an active discussion about the app on RadioReference.

Pocket25 | Running DSD-Neo on Android!

Telive osmo-tetra-sq5bpf: An Experimental TETRA Decoder that Enables Voice Decryption (If You Have the Key)

Thank you to Jacek / SQ5BPF for letting us know that he's recently released a modified version of the Telive TETRA decoder for Linux. The modification allows the user to listen to TEAx-encrypted voice signals if they have the decryption key. Typically, if a TETRA signal is encrypted, there is no way to listen to it, unless you have obtained the decryption key from the network operator, or extracted it from TETRA keyloader hardware.

But because the TEA1 encryption was broken due to a backdoor being discovered in 2023, he has also added support for using the 32-bit short key directly, which can be automatically recovered from TETRA traffic using his other software called teatime. TEA1 encryption is being phased out, but many deployments still use it.

The software is designed for advanced users to compile and run, so very little documentation is provided. However, there is a blog post here that explains the overall steps. Some additional information can be found on SQ5BPF's RadioReference post here.

TETRA Decoding (with telive on Linux)
TETRA Decoding (with telive on Linux)

Web-Spectrum: Web-Based Spectrum Analyzer and GPS Signal Analyzer with RTL-SDR Support

Over on GitHub we've recently seen a new open source program release called "web-spectrum". Web-spectrum is a multi-purpose browser-based tool. One interesting feature is that it allows you to view the GNSS spectrum (via a connected RTL-SDR or SDRplay with an appropriate antenna), decode it to a position, and also analyze the signal for jamming. It uses gnss-sdr or Gypsum as the backend GNSS processing tool.

The tool can also be used as a real-time spectrum analyzer, and for this, it supports RTL-SDR and SDRplay as well as the tinySDR Ultra spectrum analyzer.

Finally, in addition to GPS decoding, it also supports ADS-B and ISM band decoding.

Web-Spectrum: A Browser based tool for spectrum analyzer, GNSS analysis, and ADS-B and ISM band decoding.

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