Tagged: SSTV

SDR– Updated to V2.2: Many New Decoders, Tools and KrakenSDR Direction Finding and Beamforming Support Added

Last month we posted about the release of SDR-- (SDR minus minus), an open-source app that lets you visually wire together a receiver on a canvas. Since that time, Julian, the developer of SDR--, has been busy adding support for many decoders, various tools, and improving performance. Julian has also added KrakenSDR support, with radio direction-finding and beamforming blocks. Julian shares the following update for SDR-- V2.20:

New Decoders

  • Aviation and satellite: VDL2, HFDL, Inmarsat Aero and STD-C, Iridium, Drone Remote ID, 406 MHz beacons
  • Voice: TETRA, Tetrapol, GSM downlink, DECT, D-STAR, FreeDV, NXDN, dPMR
  • Data: LoRa (LoRaWAN, Meshtastic, MeshCore), ISM sensors, End-of-Train, DSC, BLE, Wi-Fi survey
  • Weather: NOAA APT, Meteor LRPT, WEFAX, radiosondes with landing forecast
  • Broadcast: DVB-T/T2, DVB-S2X, DAB packet mode, DRM with xHE-AAC

Coherent and mobile

  • Direction finding, beamforming and passive radar on the KrakenSDR
  • An iOS app with CarPlay for DF while driving is in TestFlight. Android is coming soon.

Hardware

  • Native Support: KrakenSDR, RTL-SDR Blog V4 Lite, AntSDR, PlutoSDR, SDRplay, Airspy, bladeRF and ESP-SDR
  • NanoVNA and antenna rotators
  • rtl_tcp and ADS-B Beast output for other apps

Tools

  • A satellite node with Doppler correction, plus a map with footprints and tracks
  • A spectrum monitor that classifies signals automatically, and a scanner with priorities and lockouts
  • Antenna calculator, noise figure, PER tester, SID monitor
  • Audio denoise, call recording, and a decoder log grouped by station
  • Event outputs: CSV, desktop notifications, PostgreSQL, InfluxDB

App

  • A redesigned UI with a unified look for every node
  • Multi-user editing, remote access from a browser, built-in HTTPS
  • An MCP server, so an AI assistant can build and tune a canvas

Performance

All measured on an M4 Max, full results at https://sdrmm.com/benchmarks:

  • DSP against GNU Radio:
  • FIR is 3.5x faster
  • NCO is 3x faster
  • FM demod is 4x faster
  • DDC is 1.6x faster
  • A 4096-point FFT is 1.6x faster than FFTW
  • Decoding rate in noise (48 trials per decoder across an SNR range):
  • ADS-B: 68%, against 56% for readsb and 50% for dump1090-fa
  • POCSAG: 73%, against 50% for multimon-ng
  • DMR: 81%, against 60% for dsd-fme
  • NXDN: 67%, against 23% for dsd-fme

(feel free to verify yourself with cargo xtask compare dsp)

The speed comes from hand-written SIMD kernels (NEON, AVX2, AVX-512), one shared downconversion for all channels on a radio, and a DSP path that never locks or allocates. The noise gains come from decoding IQ directly with
coherent receivers and soft decisions.

SDR-- Screenshot
SDR-- Screenshot

AI Disclaimer: This software is likely to be AI-assisted or vibe-coded.

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

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.

SDROxide: A New SDR Client for HAMs and SWLs written in Rust

Thank you to Josef (OE3JJS) for writing in and sharing with us the release of his new open-source software called SDROxide, an SDR client designed for HAMs and SWLs (short-wave listeners), written in Rust. The software supports Linux, Windows, macOS, and also has a web client. As it supports SoapySDR, RTL-SDR dongles are supported for RX. Josef writes about SDROxide:

It's a completely new project written in Rust, supporting many SDR interfaces (CAT/Audio, CAT/IQ, SoapySDR, HPSDR, TCI) and with loads of features built in that used to require extra programs: FT8/FT4, SSTV, RTTY, PSK, OLIVIA, THOR, FSQ, a CW/RTTY/PSK skimmer, there's dx cluster and sota/pota spotting, a logbook with integrations for QRZ.com, HamQTH, eQSL, LoTW, there's neural-network noise reduction, a 3D "hamclock" that visualizes QSOs, satellites, Aurora, CME cones, with up-to-date images of the sun's surface, and you can run the client locally, remote with native binary, or remote via the web (WASM).

Josef notes that the project is fully open-source and available on GitHub.

SDROxide: SSB Workspace
SDROxide: SSB Workspace
SDROxide: FT8 Workspace
SDROxide: FT8 Workspace

AI-Disclaimer: The author notes the use of local and hosted LLMs in the development of this software.

Decoding SSTV Transmissions from the QO-100 Satellite

Over on his YouTube channel dereksgc has uploaded a video showing how to decode Slow Scan Television (SSTV) transmissions from the QO-100 satellite. QO-100 is a commercial geostationary communications satellite available in some parts of the world that also carries a popular transponder for amateur radio. SSTV is an amateur radio communications analog protocol for transmitting images over a narrowband RF signal.

In the video dereksgc shows how to use SDR Console V3 together with a program like MMSSTV for decoding the image. He goes on to discuss the specific SSTV frequencies on QO-100, the different SSTV modes, and some demonstrations of images being received.

Decoding SSTV transmissions from the QO-100 satellite (QO-100 pt.2)

Receiving SSTV From the Russian UmKA-1/RS40S Cubesat

YouTuber 'saveitforparts' was recently contacted by the ground controller of the Russian UmKA-1/RS40S cubesat asking if he'd like to try and receive an SSTV image from the satellite. UmKA-1/RS40S is a small educational satellite assembled by a Russian high school. Originally it was intended for a radio astronomy experiment, but due to technical issues it's been switched to the secondary ham radio mission only.

Saveitforparts uses an RTL-SDR, directional Yagu antenna, PC running the MMSSTV decoder, and Android phone running the Stellarium satellite tracking app. After a few failed attempts he was able to eventually successfully track and receive the SSTV image as well as some telemetry.

We note that the SSTV image appears to have been specifically scheduled for saveitforparts personally, so if you try to receive this satellite yourself you will probably only be able to receive the telemetry signal.

Receiving Targeted Message From Russian Satellite

Testing the ATS25 Max-Decoder Receiver

Thank you for Manuel Lausmann for submitting his videos where he tests out and upgrades an ATS25 Max-decoder receiver. The ATS25 Max-decoder is a low cost portable HF receiver which has a large number of decoders built in such as RTTY, Hell, FT8 and FT4. Manuel notes that more decoders are still to come, such as SSTV. The built in decoders make it superior to it's predecessors the x1 and x2.

We note that the ATS25 Max appears to be around US$75 on Aliexpress, but these appear to be Max units without the "-decoder" add on. So if you are looking at purchasing one, please make sure to check that you are getting one with the text "max-decoder".

Manuel also notes that older models of the ATS25 can be retrofitted with a decoder PCB and converted into an ATS25 Max-decoder with a firmware update written by Bernhard Binns.

Note that Manuel's videos below are narrated in German, however the YouTube subtitle auto-translate feature works well enough to understand what is being said. In the first video Manuel demonstrates and reviews the ATS25 Max-Decoder, showing off some of the decoding features.

In the second video Manuel shows how to update an old model ATS25 in to the ATS25 Max by soldering on the decoder board.

Alter ATS25 umbauen zum max Decoder Teil 1 Die Hardware

Using an RTL-SDR Dongle to Receive Pictures from the ISS

Over on YouTube we've seen a good video from channel Ham Radio DX where presenter Hayden shows how to use an RTL-SDR to receive slow scan television (SSTV) images from the International Space Station (ISS). Often the ISS will transmit SSTV images down to earth on the VHF 2 meter bands as part of an event. With an RTL-SDR and simple antenna it's possible to receive those images.

In the video Hayden discusses the SSTV transmission, and demonstrates some SSTV decoding happening in real time as the ISS passes over his location. If you're looking to get started in ISS SSTV reception, this is a good video to get an idea of what's involved. He finishes the video with some useful tips for reception.

Using a RTL SDR Dongle to receive pictures from the ISS! | Software Defined Radio