Category: Digital Signals

HamRadioWeb FT8 WSJTx JTDX Remote Control Android App

Thank you to Patricio (LU5AKF) for sharing with us the release of HamRadioWeb.com's new FT8 WSJTx JTDX remote control Android app. Previously, we posted about HamRadioWeb's browser-based remote FT8 and FT4 receiver, and this Android app seems like a natural continuation of their software.

Patricio writes:

The app allows amateur radio operators to remotely control their JTDX or WSJT-X station from any Android phone or PC — no VPN, no port forwarding required.

What operators can do with it:

  • Monitor real-time FT8/FT4 decodes and band activity, just like sitting in front of JTDX or WSJT-X
  • Respond to CQ calls and transmit CQ remotely
  • Check where your signal is being heard via PSKReporter
  • Explore a worldwide activity map and a public DX spot page
  • Keep a contact log — auto-detected or manually added/imported
  • Follow community rankings and chat with other operators

The station connection is handled by a free Windows companion app (HamRadioWeb Companion) that links JTDX or WSJT-X to the user's account.

No radio at hand? The app opens in demo mode with simulated data so anyone can explore before creating an account.

Screenshots from the HamRadioWeb.com FT8 Remote Control App.
Screenshots from the HamRadioWeb.com FT8 Remote Control App.

Demod Analyzer: Analyze Digital Modulation (BPSK, QPSK, 16-QAM) in IQ Files

Thank you to Attila Zsellér, who has submitted his latest Python program called "Demod Analyzer". This program is designed for analyzing BPSK/QPSK/QAM16 signals in recorded IQ samples. Atilla writes:

I'm developing OpenStint, an SDR-based lap timing solution for rc racing and motorsport, which [RTL-SDR.COM] presented during the summer. Active transponders emit short bursts of data containing a unique id. By the time of reception, it's often full of various impairments. People are sometimes sending me IQ recordings for debugging purposes, and I was in need of a tool that can do a basic initial analysis on them, just to see if there is a chance of decoding anything.

It's a set of tools, doing a typical RX chain, with instant visual feedback:

  1. Segment the bursts of transmissions based on RSSI
  2. Apply phase/frequency offset (with an "auto" button that just works)
  3. Optional upsample + (matched) filtering
  4. Symbol synchronization
  5. Optional blind-EQ

It supports BPSK/QPSK/QAM-16. By the end of the process, you see the demodulated bits and MER & EVM figures.

There are sample recordings of actual transponders in the repository. It's Python, and the CI builds a Windows-variant. Images are in the github repository.

Demod Analyzer Screenshot
Demod Analyzer Screenshot

AI Disclaimer: The submitted notes that this program was created via vibe coding.

LakeShark: P25 Phase 1, FM, POCSAG, ADS-B and Sub-GHz with an RTL-SDR on the LilyGO T-Display P4 (ESP32-P4)

Thank you to Samuel Reynolds (aka SAMS0N1TE on GitHub), for writing in and sharing with us his project called 'LakeShark'. LakeShark is firmware for the LilyGO T-Display P4 (an ESP32-P4-based microcontroller with a 4.1 Inch touchscreen, detachable keyboard, GPS, and nine-axis motion sensor), which allows a USB-connected RTL-SDR Blog V3 or V4 to be used for P25 Phase 1 trunking, FM, POCSAG, ADS-B, and sub-GHz capture. Samuel writes:

LakeShark supports P25 Phase I conventional and trunked voice, analog FM, POCSAG pager decoding and 1090 MHz ADS-B, with a spectrum display and waterfall for tuning around.

There are a few other things that might interest your readers:

  • Passive sub-GHz pulse recording with export to Flipper .sub files, so captures can be transferred to a Flipper and opened in its Sub-GHz app.'
  • Offline maps showing aircraft and MeshCore nodes, plus GPS track recording with GPX export.
  • Mixed P25/FM scan lists and a field journal for saving notes with radio readings, position and sensor data.
  • MeshCore messaging and LoRa experiments using the onboard SX1262. The optional MIX-RF keyboard adds CC1101, nRF24 and NFC tools.

The T-Display-P4 touchscreen works on its own, but you can also use the keyboard or connect a Flipper Zero over Bluetooth. LakeShark also supports a headless ESP32-P4 Nano receiver controlled from the Flipper. That lets you keep the radio and antenna in a bag while tuning from the Flipper.

Version 2.2.0 is available now. Experimental work includes manually tuned P25 Phase II decoding, HackRF support and GPS-based scan filtering. Those have separate limitations documented in the wiki. Next steps include live-RF validation, Phase II automatic call following and further work on portable power and everyday usability.

There’s also an experimental CELL WATCH app for surveying cellular-band activity and comparing it against a saved baseline. It’s meant for spotting changes worth investigating, rather than identifying a cell site as malicious or claiming to detect an IMSI catcher.

LakeShark builds on xtrsdr, OP25 and other open-source projects. ADS-B Scope also provided a reference for part of the aircraft position decoding. Full credits are in the README.

Showcase, photos and overview:
https://terminalbay.com/?m=lakeshark-showcase

Source and credits:
https://github.com/SAMS0N1TE/LakeShark

Version 2.2.0 downloads:
https://github.com/SAMS0N1TE/LakeShark/releases/tag/v2.2.0

Flipper companion app:
https://github.com/SAMS0N1TE/LakeShark-Flipper

Wiki and guides:
https://terminalbay.com/?m=wiki

LakeShark is part of a growing repertoire of ESP32-P4 microcontroller RTL-SDR applications. Just last week we posted about OrcSDR, a standalone RTL-SDR application built around the M5Stack Tab5. Back in May, we also posted about a portable open-source 1090 MHz ADS-B firmware for the LILYGO T-Display-P4.

Previously, RTL-SDR applications have only run on full general-purpose CPUs running an OS like Windows/Linux/MacOS/Android. But the ESP32-P4 has shown that commodity microcontrollers are now powerful enough to run an RTL-SDR too, via custom bare-metal drivers and software.

LakeShark Running on A LilyGO T-Display-P4 next to a HackRF (left) and Flipper Zero (right).
LakeShark running on A LilyGO T-Display-P4 next to a HackRF (left) and a Flipper Zero (right).
LarkShark Screens
LarkShark Screens

SDR–: A Software-Defined Radio Application with Visual Signal Path

Thank you to Julian for writing in and sharing with us his interesting project called SDR-- (SDR minus minus). SDR-- is an open-source app that lets you wire devices, decoders, and displays together on a desktop window or browser-based canvas. It is described as "a software-defined radio application with a visual signal path. Connect devices, decoders, displays, and recorders on a canvas, then pin the controls you use to a rack."

A separate Rust server, which can sit on the same PC or a remote computer (like a Raspberry Pi), handles the DSP. Julian notes that SDR-- has native RTL-SDR support, and decoders for ADS-B, AIS, POCSAG, FT8, SSTV, and RDS are already implemented, with more in progress. The app also has a built-in signal generator and a repository of IQ recordings that can be used for experimentation and testing the various decoders.

The project releases are available on GitHub releases, and they cover Windows, Linux, and MacOS. 

SDR-- Screenshot
SDR-- Screenshot

HamRadioWeb: A Browser-Based Remote FT8/FT4 Receiver with Live Heatmaps, Performance Metrics and DX Cluster

Thank you to Patricio for writing in and sharing with us his release of HamRadioWeb, a browser-based remote receiver with a focus on FT8 and FT4 reception. If you're not aware, FT8 and FT4 are amateur radio digital fixed-format modes that can be decoded even with very weak signals. 

The software works by running a small server bridge app alongside JTDX/WSJT-X on the shack PC. Users can then log in from anywhere in the world on any device via the browser-based system. Once logged in, you can transmit and monitor, just as if you were sitting in a ham shack.

HamRadioWeb is designed to streamline remote FT8/FT4 operating directly from any mobile browser or PC without requiring complex setups like VPNs or port forwarding. In addition to remote TX/RX control, it features:

  • Live FT8 geospatial heatmaps and signal footprint visualization.
  • Grid-level SNR benchmarking against nearby stations.
  • Azimuthal radar & path telemetry relative to the shack.
  • Automated DXCC and award hunting synchronized with logbook data.

It’s built to make remote digital mode operating visual, data-driven, and easily accessible on the go.

HamRadioWeb is free for unlimited decodes, but limited to 10 TX's per day. Premium is a paid service costing $4.99 per month, which provides unlimited access.

HamRadioWeb: A Demo of the FT8/FT4 Terminal Display
HamRadioWeb: A Demo of the FT8/FT4 Terminal Display

IC-SDR: A New Multimode SDR Software for Windows Written in Go

Thank you to Luis Lopez Martinez for writing in and sharing the release of his open-source software, IC-SDR, a new multi-mode SDR application for Windows written in Gowith a focus on performance and efficiency. Luis writes:

IC-SDR supports AM, NFM, WFM, LSB and USB demodulation, along with several integrated digital decoders:

  • AIS
  • ADS-B (1090 MHz and UAT 978 MHz)
  • Radiosondes
  • APRS
  • RTL_433
  • DMR
  • SSTV
  • TETRA

It also includes a memory bank, real-time spectrum and waterfall displays, an audio recorder with automatic silence removal, and a frequency-segment scanner with instant triggering.

The Windows release can be found on the project's GitHub Releases page.

FreeDV RADE: An Open-Source Digital Voice Mode for HF that Beats SSB at Low SNR

Thank you to Rebecca Key (KO4KVG) for writing in and sharing with us an article she's written over on the ARDC website about a relatively new amateur open-source radio digital voice mode called FreeDV RADE.

ARDC is a private foundation that issues grants that support amateur radio and digital communications technologies. FreeDV is an ARDC grantee, and it has been using the funds to develop "a digital voice mode that could compete with SSB across varying signal-to-noise conditions on HF while providing more natural-sounding speech".

Last year, they released the FreeDV Radio Autoencoder (FreeDV RADE), which is their flagship digital voice mode. FreeDV RADE incorporates both machine learning and classical DSP, resulting in working audio at SNRs as low as -2 dB, with only half the bandwidth of a typical 3 kHz SSB voice signal. The article goes on to describe how the audio quality, power, and bandwidth efficiency are superior to other digital voice modes. 

The article also mentions how FreeDV RADE is seeing increased adoption by hardware manufacturers, with FlexRadio now supporting the mode in several radios. It also mentions upcoming improvements, including a goal of reducing bandwidth use to under 1 kHz.

FreeDV Software
FreeDV Software

Carshepherd: An Android RTL-SDR App For the Early Awareness of Nearby Emergency-Service Vehicles

Thank you to Cees for writing in and sharing his Android app, "Carshepherd," which is currently in the pre-release stage. Carshepherd works with a connected RTL-SDR and TETRA antenna to give drivers early awareness of nearby emergency-service activity (such as police, ambulance, fire) by detecting the TETRA uplink signal.

Cees notes that this is essentially the same as what hardware devices like 'Target Blu Eye' do to detect emergency services. Laser/radar detectors are illegal in most European countries, and while not advertised as such for legal reasons, Carshepherd could be a legal alternative for detecting laser/radar speed traps, detecting ProViDa video-based pacing vehicles, or just for general awareness.

The app works by continuously sweeping the TETRA bands, looking for the signature of a TETRA carrier. Once it detects a confirmed uplink carrier, it estimates proximity, which then triggers a readout and audible alert. The TETRA uplink is not always active, but emergency service vehicles often send bursts of uplink data every few seconds with GPS position updates, and, of course, during voice PTT.

The algorithm is based on a large labeled dataset from dozens of real-world test drives. The dataset trains an AI classifier that can even tell you whether an emergency unit is keeping pace with you (e.g., traveling down the same stretch of motorway as you) or whether you are approaching a stationary unit.

Carshepherd currently only works in countries whose emergency services use the TETRA communications protocol, which includes most of Europe and various other countries, but notably not the USA. However, Cees notes that they are working on a US version that will listen to the P25 network.

While Carshepherd has not yet been released, the pricing is indicated as €3.99 per month. You can sign up for the waitlist at www.carshepherd.nl.

Sept 5 2026 Update: Carshepherd is now live on the Google Play Store.

Carshepherd Android UI
Carshepherd Android UI