Category: Applications

rtl_icecast: A Terminal Application for Streaming FM to an Icecast Server with RTL-SDR

Thank you to Jouni (OH3CUF) for submitting news about the recent release of his new Linux terminal based open-source software called 'rtl_icecast', which can be used with an RTL-SDR to stream FM audio to an Icecast server.

Icecast is an open-source streaming media server that broadcasts audio and video streams over the internet.

Jouni writes:

rtl_icecast is a shell native application that uses RTL-SDR to receive FM radio signals and stream them to an Icecast server in MP3 format.

The main target usage for this app is to stream your local HAM FM repeater audio to your public shoutcast/icecast server with just a RTL-SDR USB-receiver and for example Raspberry Pi. It can be used to stream broadcast FM too, of course.

The app is native app and uses the RTL-SDR on hardware level directly. No need to pipe or install anything extra. This works out of the box (well, I hope!)."

A block diagram of how the rtl_icecast streamer works
A block diagram of how the rtl_icecast streamer works

Khanfar Phosphor: Real-time GPU Accelerated Spectrum Visualization for SDRs

We recently posted about new software programs from M. Khanfar on Feb 21 and Feb 4. So far, he has released spectrum analysis and FM demodulator software, as well as a power-based direction-finding program. Khanfar is continuing the pace and has just released a new program called "Fosphor Spectrum Visualization Windows Version" (scroll to the end of the page to find it).

This program is based on a GNU Radio backend and the Fosphor engine, a high-performance GPU-based spectrogram engine for real-time rendering. Kahnfar's software also adds frequency scanning capabilities. The software is for Windows only and consists of a single exe for ease of running. It supports RTL-SDR, Airspy and HackRF devices.

The software is free to download but is not open-source. As mentioned in the previous post, antivirus software can flag M. Khanfar's software as suspicious. We suspect these are false positive results due to the PyInstaller system used to create the exe, but please take your own precautions just in case.

Also, we just want to note that this program is based on the GPLv3 licensed https://github.com/osmocom/gr-fosphor. With this program not being open source, we are unsure if it violates the licensing. If any licensing experts are on here, please chime in on the comments.

UPDATE: Khanfar has released the code on GitHub under the GPLV3 licence, so all licensing concerns are alleviated.

Fosphor Spectrum Visualization Windows Version

TechMinds: Using your RTL-SDR Locally with Just a Web Browser

In the latest video on the TechMinds YouTube channel, Matt shows how an RTL-SDR can be used with a browser-based RTL-SDR web app at https://radio.ea1iti.es. We've featured EA1ITI's RTL-SDR web app a few times on the blog in the past, as it's a nice demonstration of what the HTML5 USB API is capable of.

In the video, Matt shows the software in action, receiving signals and he goes through the various settings available.

More information about the software can be found on the help page at https://radio.ea1iti.es/help.html, and the software is available on GitHub.

How To Use Your RTL-SDR Locally With Just A Web Browser

Khanfar Direction Finder: RTL-SDR and Directional Antenna Based Direction Finding Software

Recently, on Feb 21, we posted news about the release of some spectrum analysis and FM demodulator software from M. Khanfar. Now he has just released his latest software "Khanfar Direction Finder" (scroll to the end of the page), a Windows radio direction finding tool for RTL-SDR dongles.

Khanfar Direction Finder appears to work on the principle of power measurements through the use of directional antennas. Four directional antennas are connected to four RTL-SDR dongles positioned in the N/S/E/W directions.

The antenna pointing towards the signal source will receive it stronger and the antenna pointing away from it will receive it weaker. The two other antennas may receive the signal with some intermediate strength based on the angle. The software automatically combines the power information from all four antennas, resulting in a bearing.

The 'Quintet' version of the software also contains a map that can be used to plot the determined bearings.

Both versions of the software are free to download but not open-source. As mentioned in the previous post, antivirus software can flag M. Khanfar's software as suspicious. We suspect these are false positive results due to the PyInstaller system used to create the exe, but please take your own precautions just in case.

Khanfar Direction Finder Compass Screen
Khanfar Direction Finder Compass Screen
Khanfar Direction Finder Map Screen
Khanfar Direction Finder Map Screen
Khanfar Direction Finder

RTL-SDR Jamming Detector Software

Over on GitHub, Alejandro Martín has recently released his open-source 'rtl-sdr-analyzer' software, which is an RTL-SDR-based signal analyzer and automatic jamming detector. The software is based on Python and connects to the RTL-SDR via an rtl_tcp connection.

Alejandro's software is advertised as having the following features:

  • 📊 Real-time Visualization: Advanced spectrum analysis with waterfall display
  • 🔍 Smart Detection: Automatic signal anomaly and jamming detection
  • 📈 Dynamic Analysis: Adaptive baseline calculation and threshold adjustment
  • ⚙️ Flexible Configuration: Fully customizable detection parameters
  • 🌐 Network Support: Built-in RTL-TCP compatibility for remote operation

The software works by continuously monitoring a frequency range, and creating a log whenever a signal is detected that exceeds a certain power value and duration. It can also monitor 'z-score', which determines if the current signal mean has deviated significantly from the baseline, which could indicate a jamming or interference event.

rtl-sdr-analyzer: An RTL-SDR Signal Analyzer & Jamming Detector
rtl-sdr-analyzer: An RTL-SDR Signal Analyzer & Jamming Detector

TechMinds: Building a Portable ADS-B Aircraft Tracker and VHF Airband Radio Receiver

Over on the TechMinds YouTube channel, Matt has uploaded a video demonstrating a portable ADS-B aircraft tracker with VHF airband radio reception as well. The build consists of a 7-inch screen, Raspberry Pi 4 and two RTL-SDR dongles.

In the video, Matt shows what hardware is required, how it's all put together, and how to install the OS and software and set it up. The software Matt uses for displaying aircraft is tar1090, a comprehensive web interface for ADS-B data. For receiving AM VHF airband communications, he uses an HTML5-based RTL-SDR receiver that can run directly in the Chromium browser and connect to a local RTL-SDR through the web interface.

Your Very Own Aircraft Tracker With VHF Airband Radio - RTL-SDR & PiADSB

calcRadio: A Casio FX-CG20 Calculator Front End Interface for RTL-SDR

In the past, RTL-SDR.COM reader JJ has shared with us his LegoPi project, which demonstrated a clever way to enclose a self-contained RTL-SDR build, as well as his multi-feature living room radio build, which combined an RTL-SDR for live radio and an internet-based radio system with MP3 player.

Recently, he submitted to us a new project called 'calcRadio' (information about the calcRadio can be found at the end of the linked page). The calcRadio project consists of a similar self-contained RTL-SDR build as seen in his previous projects (RTL-SDR with speakers and a single-board computer), but this time, it's controlled via an old Casio FX-CG20 calculator. The calculator's interface is programmed in C, and JJ has uploaded his open source code on GitHub.

JJ writes:

The front-end is made of an older CASIO calculator, the fx-CG20, which can be programmed in C thanks to the non-official CASIO SDK: https://github.com/Jonimoose/libfxcg/releases (the fx-CG20 built-in basic language was way too slow).

The back-end is same as last build, a Strong SRT 2023 TV box, flashed with Armbian + Ubuntu and a bash script to handle everything. Under Linux, the Android board is known as Amlogic Meson GXL (S905X) P212 Development Board. It has about the same CPU power as a Raspberry Pi 3 Model B+ but with less power consumption, built-in storage and infrared port.

The key to make it work was the presence of a cloning port on the calculator, which was connected to the UART port on the Android board, allowing serial communication to be established.

The calcRadio build

TechMinds: Building a DIY Standalone SDR with a Raspberry Pi, 5-Inch TouchScreen, SDRplay RSPdx and the PiHPSDR Software

Over on the TechMinds YouTube channel, Matt has uploaded a video showing how he created a DIY standalone SDR using an Elecrow 5-inch touchscreen display, Raspberry Pi 5 and an SDRplay RSPdx. The software he uses is PiHPSDR, which is compatible with the SDRplay and RTL-SDR dongles.

In the video, Matt shows how to set up the hardware, the Raspberry Pi OS, and the required software and drivers. He then shows the setup running PiHPSDR and the various settings and features available in the software.

Could This Be The BEST SDR Receiver? Using PiHPSDR & SDRPlay RSPdx