Category: Applications

VibeSDR Now Available on the Apple App Store + Running on an Apple Watch

Back in June, we posted about VibeSDR, an AI vibecoded free and open-source mobile SDR client for rtl_tcp and UberSDR/KiwiSDR/OpenWebRX servers developed for iOS and Android. Recently, Stuart Carr (Stuey3D) wrote in again to let us know that VibeSDR is now available on the Apple App Store for £2.99 and is soon to be available on the Android Play Store too.

In terms of updates, Stuart also notes that he's now developed VibeServer, which provides a more network-efficient way to share RTL-SDRs remotely via an Android phone. VibeServer compresses the data and transfers it at 120KB/s instead of the full 4.8MB/s required by rtl_tcp. 

Stuart has also developed an Apple Watch Buddy app version of VibeSDR which runs directly on an Apple Watch, allowing you to view and listen to the spectrum on your wrist. The watch version is still in beta, but Stuart notes that you can join the free beta on TestFlight.

As before, the latest open source code can be found on the VibeSDR GitHub https://github.com/stuey3d/vibesdr.

Finally, Stuart has provided us with 20 free promo codes to give away for the Apple App Store version of VibeSDR. To win a promo code, simply comment on this post (making sure to enter an email in the email field), reply to the X post, or comment on the Facebook Post (note that for Facebook you must montior your comment for a reply as Facebook does not allow private messages). 

Update: All promo codes have now been allocated, thanks!

AI-Disclaimer: This software was vibecoded with Claude.

VibeSDR Running on an Apple Watch
VibeSDR Running on an Apple Watch
Introducing VibeSDR Jr: A full SDR Client on your wrist.

TrojPix: Covertly Transmitting Data from Air-Gapped Systems via Video Cable Emissions

Researchers from the University of Shandong have recently demonstrated in a paper that they can transmit data from an air-gapped PC by using a Trojan to implement imperceptible pixel modulation in a monitor.

Every electronic device unintentionally emits RF, and PC monitors, TVs, and screens are no exception. In the past, we have shown that with simple TEMPEST tools, it is easy to recover the image on a screen over a distance using an RTL-SDR or Airspy SDR.

TrojPix relies on the unintentional emitted RF from a PC monitor's video cable. By subtly modulating the pixels on a screen, it is possible to enable data transfer via the unintentional emissions. This means that any PC infected with the TrojPix Trojan could transfer data wirelessly to a snooper, even if the PC is totally disconnected from any wired or wireless network. The only way to stop such an attack would be to completely shield the PC with a faraday cage.

The team note that they were able to achieve a peak data throughput of 8.1 MBps over a max range of 208 meters. They tested nine commercially available monitors and fifteen digital video cables, each demonstrating significant usable RF leakage.

The receiver hardware used was a USRP X310 software-defined radio sampling at 10 MHz and the transmissions appear to have been at 148.5 MHz and 297 MHz.

TrojPix Experiment: Receiving Data over 210 neters,.
TrojPix Experiment: Receiving Data over 210 neters,.

DeepSDR: Building a Live Public Safety Incident Map with an RTL-SDR, Whisper and an LLM

Over on Reddit and YouTube, user Hubquhq has shown how he created a live incident map using an RTL-SDR, Whisper and an LLM. The idea behind the system is to monitor multiple public safety voice communication channels with an RTL-SDR, transcribe everything into text using Whisper, and then use an LLM to categorize events and extract details such as addresses. Categorized incidents are then plotted on a map, allowing the user to visualize patterns. 

For example, in his YouTube video, he shows how he mapped cardiac, animal, drug overdose, vehicle collision, rescue, and hazmat events over time, building a powerful database of what is happening in his city.

The program and code does not seem to be available for download anywhere, but Hubquhq does provide a contact link for anyone interested. 

Systems that can monitor every RF voice and data channel on the spectrum and summarize them via an LLM are something we expect to see more of in the future as AI and LLMs improve.

Updates: Updated post with more information here.

DEEP SDR: How I Built an Incident Map

Exploring the Art and Science of Spectral Painting with SDR

Thank you to Paul Maine, who wrote in and wanted to share some experiments he and Gary Schafer have been doing with spectral painting. Spectral painting is the art of drawing pictures directly on the spectrum waterfall, which a software-defined radio makes visible. Paul has written the post below:

What happens when radio technology meets digital artwork? The result is something fascinating called Spectral Painting—the ability to create images that appear inside the radio frequency spectrum.

Gary Schafer (@signalgalaxiesunlimited) and Paul “The SDR Guy” Maine (@paulmaine6433) have teamed up to explore this unique combination of software-defined radio, signal processing, and creativity. Together, they have created companion videos on Spectral Painting and released them at the same time, each approaching the topic from a different perspective. For the best experience, it is recommended to watch Gary’s video first, followed by Paul’s practical demonstration.

Gary begins the journey by diving into the theory behind Spectral Painting. Using GNU Radio flowgraphs and GNU Octave scripts, he explains how images can be transformed into signals and displayed within the frequency spectrum.

Paul then takes Gary’s GNU Radio flowgraph and GNU Octave scripts from theory into practice. Using multiple SDR platforms, he demonstrates how to transmit spectral images using both the HackRF and TRX-DUO SDRs. He then completes the process by receiving and displaying the images using several different SDR receivers, including the RTL-SDR V3, RTL-SDR V4, and Airspy HF+.

Together, these videos provide a complete journey—from understanding the science behind Spectral Painting to seeing it come alive on real SDR hardware.

Below is an example screen capture of Spectral Painting in action.

Spectral Painting Example
Spectral Painting Example

Start with Gary’s video to learn the concepts and signal processing techniques:

Creating Spectral Paintings using Gnu Radio Companion (and other open source tools)

Then watch Paul’s video to see Spectral Painting transmitted and received using real SDR equipment:

E30 Spectral Painting

Adding HD Radio Support to FM DX Webservers with an RTL-SDR

Thank you to Ivan (NO2CW) for submitting news about how he added HD Radio decoding capability to his FM DX Webserver receiver. The FM DX Webserver is a community of worldwide FM broadcast-band online receivers that mostly use SDRs based on the TEF6686 chip, with a few also using RTL-SDR receivers. HD Radio (aka nrsc5) is a proprietary digital audio standard used by FM broadcasters in North America. It's often observed by SDR users in a waterfall as the two rectangles flanking both sides of a broadcast FM signal. Ivan writes:

A major challenge has been that up until now none of the online receivers were HD Radio capable. I have now added this capability with the help of an RTL V3. The online receiver uses a combination of two receivers: a TEF6686 which is known to be highly sensitive and, when an FM HD Radio signal is present, an RTL V3 automatically kicks in to provide HD radio capability opening up HD1, HD etc audio streams together with bundled album art, traffic and weather. The program was initially conceived by discord user seehed and then further developed by me.

The core code for this plugin was developed by GitHub user seehed and can be found here: https://github.com/Seehed/NRSC5_HDRadio. I had to make a few tweaks to get it fully working.

How the Setup Works: The hardware setup requires both a TEF6686 receiver and an RTL dongle operating simultaneously.

I tested an RTL-SDR V4 first, but the necessary DLLs worked much better with an RTL-SDR V3 in my current build.

By default, the server uses the TEF6686 for browsing the FM band for analog signals. When a user tunes to a frequency where an HD Radio signal is present, the logic switches to "HD Mode" and the RTL V3 takes over. The NRSC5 library is used to process the digital signal. In this mode, users will notice the change in audio quality and the available subcarrier streams (HD1, HD2, HD3, etc.) become visible and selectable.

How Users Can Set It Up: To replicate this, a user would need:

  • A working FM DX Webserver with a TEF6686.
  • An RTL-SDR V3 plugged into the same host.
  • The NRSC5 library installed.
  • The plugin from the GitHub link above installed and configured in the webserver directory.

Ivan also notes that currently his Miami NO2CW receiver is the only one on the network supporting HD Radio.

HD Radio on FM DX Webserver. Receiving HD Radio inside the fm dx webserver application.

HD Radio Added to FM DX Webservers via an RTL-SDR
HD Radio Added to FM DX Webservers via an RTL-SDR

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

Testing WSPR HF Propagation with a Raspberry Pi 3B+ and TAPR Shield Running WsprryPi

Thank you to Simone Spadino (SWL ID I8926BA), who wrote in to share his low-cost WSPR setup. WSPR (Weak Signal Propagation Reporter) is an amateur radio mode designed to test propagation paths using very low-power transmissions, with receiving stations reporting spots in real time to the WSPRnet map.

Simone's setup consists of a Raspberry Pi 3B+, which can be made to modulate a square wave RF signal on one of its GPIO pins via the WsprryPi software. Because a square wave generates many harmonics, he used the 20m WSPR shield from TAPR, which provides a low-pass filter to remove them. A dipole made from simple electrical monopole wire was connected to the shield via 50 ohm coax, and the signal was transmitted at 14.0971 MHz.

Transmitting from his rooftop in the center of Bari in southern Italy, Simone had his beacon received in England, Finland, Cyprus, and the Canary Islands, all more than 3100 km away. He repeated the experiment a week later with similar results. This is a reminder of how far low-cost hardware can transmit with a resilient protocol like WSPR.

Simone's WsprryPi Setup
Simone's WsprryPi Setup
WSPR Range with the Raspberry Pi 3
WSPR Range with the Raspberry Pi 3

InmarScope: An Inmarsat AERO and STD-C Decoder with Multichannel Decoding and Automatic Call Following

Over on the SignalsEverywhere YouTube channel, Sarah Rose has released InmarScope, a multichannel L-band Inmarsat decoder that connects directly to an RTL-SDR, Airspy, or HackRF. The software can receive and decode both aeronautical (AERO) and maritime (STC-C / EGC) traffic at the same time. Decoders are dropped directly onto the aligned FFT and waterfall by holding CTRL and left-clicking, and the software lets you stack Aero MSK (600/1200 bps), high-rate OQPSK (10500 bps), AMBE voice (8400 bps), and Inmarsat-C BPSK decoders side by side.

One of the more interesting features is automatic voice-call following. By monitoring the 10500 baud forward-link channels, InmarScope can receive C channel voice assignments and automatically retune the SDR to the assigned frequency, lock the carrier, decode and record the AMBE call, and then hop back to where it was. There is also a two-SDR mode that dedicates a second radio to voice with a live split-view spectrum so one radio stays on the P control channel while the other tunes to voice calls. For assignments that never get broadcast, there is also a Call Hunter feature that uses a squelch threshold to automatically drop the decoder when a call appears. When a call is playing, the built in flight map also decodes the aircraft hex ICAO address and looks it up on airplanes.live, showing the plane's position and route in real time.

Recent updates have added a community-editable band plan, message search and filtering, an IQ recorder that also captures the seconds before you hit record, and a web dashboard for browsing decoded data from a phone.

The software is completely open source on GitHub, and the C++ code can be compiled from source, or a precompiled Windows build is available on sarasforge.dev for $15, with Sarah's Patreon patrons getting it free.

We note that Inmarsat signals such as AERO and STD-C/EGC can be received with our RTL-SDR Blog L-band Patch Antenna, which is available in our store.

Multi-Channel Voice Following Inmarsat Decoder for Windows!

Decoding Inmarsat in 2026