Tagged: airspy

VMA Radio Lab: DecSAT Extended into a Multi-SDR Receiver with DVB-T/T2, DAB+ and Analog PAL TV

Last week we posted about DecSAT, an open-source program by CasualArclamp that turns a HackRF One into a DVB-S/S2/S2X satellite receiver and analyzer. Now Vitor Martins Augusto has written to share his fork, 'VMA Radio Lab' (initially called DecSAT-VMA), which extends DecSAT into a general-purpose broadcast receiver and measurement tool.

The biggest difference between DecSAT and VMA Radio Lab is multi-SDR operation. VMA Radio Lab can run several SDRs at once, each with its own VFOs, including the HackRF, PlutoSDR, USRP B210, RTL-SDR, SDRplay RSP1 and Airspy. One SDR can be dedicated to a sweeping wideband overview, such as the full 950 - 2150 MHz satellite IF. It also pulls in DVB-T/T2, DAB/DAB+ and TETRA decoding from CasualArclamp's sibling projects DecDVB-T, DecDAB and DecLAB, and adds analog radio, PAL color TV with teletext, measurement tools such as a vectorscope and transport stream analyzer, and control of CrazyScan-compatible TBS tuner cards for LNB power and hardware DVB reception.

Meanwhile, the original DecSAT remains satellite-focused. Since our last post it has added support for Fobos SDR, Airspy and network IQ input (including rtl_tcp), and has merged some of VMA's early RTL-SDR, PlutoSDR, B210 and analog TV code.

VMA Radio Lab is GPLv3 and available as a Windows 64-bit build and source zip on the website. We note that TETRA audio needs a separate ACELP codec DLL that isn't included for legal licensing reasons, and the bundled development notes describe several of the newer decoders, such as AIS and ACARS, as experimental. 

Decscat-VMA Screenshot
Decscat-VMA Screenshot

AI Disclaimer: The original DecSAT lists Claude as a contributor. While VMA does not disclose it, the development notes included with the VMA Radio Lab source suggest that its extensions were also written with the help of AI.

dec406: Decoding Second-Generation COSPAS-SARSAT 406 MHz Distress Beacons with an RTL-SDR

Thank you to Fabrice Morel (F4MLV) for writing in and sharing his project 'dec406', an open-source Linux decoder for COSPAS-SARSAT 406 MHz distress beacons. These are the EPIRBs carried on ships, ELTs on aircraft, and personal locator beacons (PLBs) carried by hikers. When activated, they transmit a digital message with a unique ID and often a GPS position, which satellites relay to rescue coordination centers.

What makes dec406 interesting is that it decodes the newer second-generation beacons. Unlike the narrowband first-generation signal, these use a ~50 kHz wide DSSS/OQPSK spread-spectrum signal that must be despread and BCH error-corrected before it can be read. Fabrice tested it with an RTL-SDR, and Bernard (F6BVP) at the F4KLO La Villette radio telescope used an Airspy on the MEOSAR satellite downlink near 1544 MHz, decoding system and calibration beacons in the USA, Cyprus, Brazil and Togo.

Fabrice has published real IQ recordings, and running 'make demo-real-sgb' downloads one and checks the decode. The live scanner supports RTL-SDR, Airspy, PlutoSDR, and HackRF, and the code is MIT licensed. More details are in the F4KLO field report. As Fabrice notes, never radiate test transmissions on 406 MHz. Fabrice has also sent us a PDF article of his results, which you can download here.

A Wide SGB Burst Near 406.05 MHz Received with an RTL-SDR in SDRangel (Top), dec406 Decoding a French Second-Generation System Beacon in Self-Test Mode (Bottom)
A Wide SGB Burst Near 406.05 MHz Received with an RTL-SDR in SDRangel (Top), dec406 Decoding a French Second-Generation System Beacon in Self-Test Mode (Bottom)

AI Disclaimer: While Fabrice does not mention it, the dec406 README and .gitignore reference a "Claude assistant memory" CLAUDE.md file, which suggests that Claude was used to help develop the software.

NightDX: Automated Overnight Shortwave DX Listening with an Airspy HF+

Thank you to Marco Zennaro for writing in and sharing NightDX, a free terminal app for macOS, Windows and Linux that lets an Airspy HF+ do your overnight shortwave listening for you. The menu interface is deliberately styled like early-90s DOS software.

NightDX pulls the EiBi, AOKI and HFCC broadcast schedules, plus live solar flux and Kp from NOAA. A propagation model then predicts what should reach your location and calibrates itself against what your own radio hears. The HF+ sweeps all the bands in about 10 seconds to see which carriers are really there, and overnight NightDX records the best stations, putting ones you've never logged first.

Optional AI features can then label each recording as speech, music, or noise using an AudioSet classifier, and transcribe and translate it with OpenAI's Whisper, which helps when writing reception reports. In the morning, a browser report shows the recordings with audio players, one-click reception reports drafted in Gmail, and a QSL card log.

We note that NightDX doesn't claim to identify stations. It shows schedule names as candidates and flags recordings where the evidence doesn't fit, such as the wrong language or a signal far too strong for the predicted path. Only the Airspy HF+ (Discovery or Dual Port) is supported for now, so there is no RTL-SDR support. Marco notes that other SDRs such as the Perseus and Elad are being looked into. The code is open-source under the MIT license and available on GitHub.

NightDX Screenshots
NightDX Screenshots

AI Disclaimer: Marco notes that NightDX was built with the help of Claude.

sdrtop Update: Wi-Fi Airtime Tools, POCSAG Pager Decoder and Native Airspy R2 Support

Earlier this month we posted about sdrtop, a Rust-based SDR bench instrument that runs in a terminal and is aimed at measurement rather than listening. Viktor László (MusiThang on GitHub) has now written in again to share several updates. Viktor notes that the goal is still to "make radio signals and the measurements behind them inspectable, rather than hiding everything behind a decoded result."

The biggest additions are new Wi-Fi tools. sdrtop can now survey 2.4 GHz channels 1 to 13 and name the least busy one, inspect a single channel frame by frame at three time scales, and show a channel's airtime use second by second. These tools need 20 Msps, so you need an SDR like the HackRF. There is also a new POCSAG pager decoder written from the ITU standard without external libraries. Viktor tested it over the air by transmitting with a HackRF and PortaPack Mayhem and receiving with an Airspy R2.

The Airspy R2 is now natively supported too. Its gain staging follows the R2's Linearity and Sensitivity gain curves, and sdrtop warns you before the tuner clips. RTL-SDRs are still fully supported, and native support for the SDRplay RSP1B and Airspy HF+ Discovery is in progress. The code is open source under the GPLv3 and available on GitHub.

Some screens from sdrtop
Some screens from sdrtop

AI Disclaimer: The project's CREDITS.md file notes that Claude Code was used for implementation, architecture discussion and problem-solving.

Demod Updates: Adds Support for OpenWebRX, FT8 Decoding, CarPlay and an Android Version

Back in July, we posted about Demod, an iOS and iPadOS SDR receiver app that works as a client for rtl_tcp, SpyServer, and KiwiSDR. The developer, Alphonse, recently wrote in again to share updates. Alphonse writes:

Since the launch, Demod has added:

  • OpenWebRX support on top of KiwiSDR, SpyServer and rtl_tcp. Public receivers are browsable on a built-in map, so it can be tried without any hardware.
  • FT8, CW and RTTY decoding on the phone.
  • Identify. Tap an unknown signal and it measures it, checks the shortwave broadcast schedules against the receiver's location and the time, and names the likely station and how far away it is.
  • Live on-device transcription and translation of what you're listening to.
  • CarPlay, and a "car radio" Seek that jumps to the next real signal for the current mode and stops there (the next AM station, SSB voice or CW signal). It also works from headphones and the steering wheel. 
  • A band scanner, recording and 15-second rewind of live radio, and Siri ("Tune Demod", "Ask Demod what this signal is").
  • A three-pane iPad layout, a mains-hum filter, an auto-contrast waterfall and squelch that works on every source.

Android: Demod is now on Google Play, with the same receiver support and decoders. Android Auto support coming soon.

Alphonse has also decided to share with the community 15 free codes for each platform that let you download the app for free. These codes are first come, first served, so if a code no longer works, it will have already been claimed.

iOS (iPhone/iPad) — redeem in the App Store app: tap your profile photo → Redeem Gift Card or Code. Or tap the link directly: https://apps.apple.com/redeem?ctx=offercodes&id=6782193839&code=CODE1
KTKAWEXFT36F, LWPN4RNLTFMK, HMJKF39KLPN9, FM7JEHP7H7XA, 3F9PALW93KYM, MJ7TH3E9E3W9 ,P7P3NJR66XKT, K7WKYKNNRPMY, 94WLYNRLKNFR, 4XE7WAYHX4PN, 3KLPHAE9TTHX, MY64T9JWW3HA ,TXWWHNPMNYAX, LPJALTHR966K, EMRLANKKF7L6

Android — redeem in the Play Store app: profile icon → Payments & subscriptions → Redeem code. Or tap the link: https://play.google.com/redeem?code=CODE1
3SD4H680XKNUGNP9V6SXT8U, 68XKMWQEGUXLW2T6W41XEUR, 2N8E2KY22V9L49D92NQ86DX, VHG4UJPUJ6DGRVZGYGA331Z, 3N48JPPJ8F5RUA9S2E55C2N, 7N4BMSA3X1J893QQGC9H6ZM, VVQBLBGFBJED9GU7Y3UZQZK, NTC82UE8KT1RMSFF9GW1LVA, LBLKS33KUG3PQML1KYVK2P2, 9THCT76YXV61HAFK9ZY22J7, CMF62T6LA46V6PVCUZ4BYZG, S895G4U1E5FZ3QZA255FPU1, QQR944S4BUCA1XKCEBAJPPU, PDYWFXGWUJBV9C9UACTJ065, EXZRMG3RB3XJUEB42Z6KTZH

Demod iOS and Android Client for WebSDRs
Demod iOS and Android Client for WebSDRs

OnAir: A Digital TV and DAB Decoder for SDRs

Thank you to Kristijonas for writing in and sharing with us his project, OnAir. OnAir is an easy-to-use digital TV decoder for DVB-T2, DVB-T, ATSC 1.0, ATSC 3.0, ISDB-T, and a digital audio decoder for DAB / DAB+ and FM Radio. It also supports Analog TV modes such as PAL, SECAM, and NTSC, and data modes like ADS-B, GNSS (GPS, GLONASS, BeiDou), and DMR.

It supports various wideband SDRs, including HackRF, PlutoSDR, BladeRF, LimeSDR, USRP, Airspy R2, and SDRplay. RTL-SDRs unfortunately do not have enough bandwidth to decode digital TV channels in SDR mode, but the software still supports RTL-SDRs for narrowband signals.

The software is easy to install, with an installer .exe being available for Windows, a .deb file for Debian Linux, and a .dmg file for macOS. 

OnAir Screenshot
OnAir Screenshot

AI Disclaimer: This software lists Claude as a contributor.

OpenWXSDR Updates: Decoder Improvements and Sondehub.org Uploads

Back in May, we posted about the release of OpenWXSDR, an open-source Python framework that turns one or more RTL-SDR or Airspy SDRs into a fully automated radiosonde ground station running on a Raspberry Pi 4/5 or Linux x86 machine.

Recently, OpenWXSDR creator Mike (DL2MF) wrote in to share that V1.0.62 has been released, bringing improvements to decoder quality and stability. The update also improves the software's setup and configuration stages and adds a radiosonde statistics page.

Another development is that the sondehub.org aggregation site has verified the OpenWXSDR telemetry data and now allows the upload of DFM06, DFM09, DFM17, M10, M20, RS41, and RS92 radiosonde data to its network via OpenWXSDR.

OpenWXSDR Screenshot
OpenWXSDR Screenshot

Tech-ni-shn Measures RTL-SDR Blog and Airspy Sensitivity

Thank you to Kevin Murphy (ZL1UJG) (aka Tech-ni-shn) for writing in and submitting some RTL-SDR and Airspy sensitivity measurements that he has recently done over on his YouT ube channel. In his tests, Kevin measures an RTL-SDR Blog V4, RTL-SDR Blog V3 + SpyVerter, Airspy HF+ Discovery, and Airspy Mini using a signal generator, attenuators, and SDR#.

His results show that the RTL-SDRs and Airspy devices have very similar minimum discernible signal (MDS) levels, all measured around ~-133 dBm. Kevin has provided a PDF summary of his results, and the video below.

Video#012 SDR Sensitivity and Noise figure