Category: Digital Signals

Using an RTL-SDR to Decode Broadcast FM RDS Data on Android

Over on YouTube Double A Labs has posted a new video demonstrating how to use an RTL-SDR and Android device to receive broadcast FM stations, and to decode any associated RDS data. 

In the video Double A uses the SDR Touch Android app and the Advanced RDS function to show the RDS information. He goes on to explain the various pieces of information RDS data provides including clock time, active RDS groups and alternative frequencies.

Tune broadcast FM radio and decode Radio Data System (RDS) information using your Android phone and an RTL-SDR USB (see parts list below). RDS can include station identification, song name, the current time for a receiver to sync its clock, alternative frequencies the same program is on, and more!

Tuning FM Radio & Decoding RDS Data on ANDROID using RTL-SDR USB

Frugal Radio: Travelling with SDR & Scanner Gear

Over on his YouTube channel Frugal Radio, Rob has uploaded a new video whilst on holiday travelling through the USA. In the video he shows what sort of scanner radios, antennas and SDR gear he carries with him on his travels. His gear includes a Uniden SDS-100 scanner, a BCD325 scanner, a Radio-Tone RT4 internet network radio and of course an RTL-SDR Blog V3 and laptop.

He goes on to demonstrate the hardware in action from his Hotel room, decoding local digital audio.

A peek in Frugal's Travel Bag : SDR & Scanner gear on the road

Lon.TV Demonstrates Decoding Various Digital Signals with RTL-SDR

Tech YouTuber Lon.TV has recently uploaded a video demonstrating how to identify and decode various digital transmissions with an RTL-SDR dongle. In the video he explains how to use VB Cable to pipe audio from SDR# into various decoders, and then goes on to show DMR, APRS, POCSAG, L-Band AERO, FT8, and JS8/JS8CALL all being decoded via an RTL-SDR Blog V3 dongle.

Software Defined Radio Part 2 - Decoding Digital Transmissions with an RTL-SDR USB Radio

Controlling a Toy RC Car with a HackRF

Over on his blog Radoslav has created a post showing how he has used a HackRF to wirelessly control a toy RC car by reverse engineering the wireless control protocol, and generating the control signals in a C++ program.

Having already created the rf-car HackRF RC car control software on GitHub a few years ago, Radoslav was easily able to modify it for a new RC car that his daughter received. The process was to simply look up the FCC data on it, finding that it operated with 2.4 GHz and used GFSK modulation. He then used the Inspectrum signal analysis tool to determine the bit strings used to control the car. Finally using, his C++ interface to the HackRF he implemented the new bit string and GFSK modulation.

The video below demonstrates Radoslav controlling the RC car with the keyboard on his laptop.

Controlling 2.4GHz FSK car with HackRF

In the past we've posted about another project that also used a HackRF and computer to control a RC drift car, and another project that used the RPiTX software to control an RC toy car with GNU Radio and a Raspberry Pi.

[Project also seen on Hackaday]

Running GR-GSM and IMSI Catcher on a Raspberry Pi 4 with Dragon OS

DragonOS is a ready to use Ubuntu Linux image that comes preinstalled with multiple SDR software packages. The creator Aaron also runs a YouTube channel showing how to use the various packages installed. 

In his latest video Aaron tests his Pi64 image with GR-GSM and IMSI Catcher running with the GNU Radio 3.10 platform on a Raspberry Pi 4. He tests operation with an RTL-SDR and LimeSDR.

GR-GSM is a GNU Radio based program capable of receiving and analyzing mobile GSM data. We note that it cannot decode actual messages without additional information about the encryption key, but it can be interesting to investigate the metadata. GSM is mostly outdated these days, but still used in some areas by some older phones and devices. IMSI Catcher is a script that will record all detected GSM 'IMSI' numbers received by the mobile tower which can be used to uniquely identify devices.

Short video setting up and testing GR-GSM on DragonOS Pi64 w/ GNU Radio 3.10 and the RTL-SDR. The current DragonOS Pi64 build has GNU Radio 3.8 and all the necessary tools to accomplish what's shown in this video. If you'd like to test the build shown in this video, it's temporarily available here until I finish and put it on Source Forge.

A LimeSDR and DragonOS Focal's Osmo-NITB-Scripts was used to create the GSM900 lab environment. The RTL-SDR was able to see and decode the GSM900 network and although only briefly shown in the video, the IMSI Catcher script works.

Here's the fork used for this video and for testing. There's also a pull request on the main GR-GSM repo for this code to be added.

DragonOS Pi64 Testing GR-GSM + IMSI Catcher w/ GNU Radio 3.10 (RTLSDR, Pi4, LimeSDR, OSMO-NITB)

Troubleshooting TV Reception with Spektrum and an RTL-SDR

Thank you to "Double A" for submitting his latest YouTube tutorial video that shows how to use an RTL-SDR together with the Spektrum software to optimize TV reception by comparing TV antennas, repositioning antennas and detecting interference.

Double A's video first shows how to setup the RTL-SDR and how to install and use the Spektrum analyzer software. He then compares a popular highly rated phased array TV antenna against cheaper log periodic TV antenna, with the results showing that the phased array works a lot better at most TV frequencies even with accurate positioning. He goes on to show how he scans for FM, 5G and local electronics interference and the effect of an FM filter can help.

RTL-SDR USB as Spectrum Analyzer to Improve Antenna TV Reception and Detect Interference

DAB+ Decoder Version 2.4 Released and YouTube Demonstration Video

Version 2.4 of the RTL-SDR compatible DAB/DAB+ decoder called has recently been released for download on GitHub. The main changes include various bug fixes, the addition of Windows 11 support, and the return of the Android APK (but only with rtl_tcp support).

The author has also released a new YouTube video tour, demonstrating the software in action, and explaining all the features.

Showing a SDR to listen DAB/DAB+.

Demonstrating the New 3D Maps in SDRAngel

In December of last year we posted about a video demonstrating the many features that the SDRAngel software comes standard with. Recently they've added a new feature which are 3D maps that can be used to visualize signal data.

In the latest video demonstration they show these 3D maps projecting NOAA weather satellite images onto a 3D globe and at the same time tracking the NOAA satellites over the globe as it produces imagery. They also show the software visualizing a 3D model of aircraft on the globe, using live ADS-B data to show aircraft maneuvers when taking off, cruising and landing. With multiple SDRs they also show how the visualization can be combined with air traffic voice. Finally they also show marine vessels being visualized via live AIS data. There appear to be a wide range of vessel 3D models implemented.