Tagged: shortwave

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.

SimTX: A Multiplayer Shortwave Radio Simulator with Realistic Propagation and rtl_tcp Support

Recently, we came across SimTX, an open-beta multiplayer shortwave radio simulator. Everyone shares the same simulated band, so whatever one user transmits from their virtual station can be picked up by anyone else, simulated propagation permitting. The website suggests running a pirate station, making your own numbers station, or just tuning around and listening.

For realism, the ionosphere is based on IRI-2020 climatology with live ionosonde data assimilated on top, groundwave and noise follow ITU-R models, and every link passes through a Watterson fading channel with Doppler, multipath and storms. Users can transmit from a mic, an audio file or raw IQ from GNU Radio in modes including AM, SSB, CW, NFM, WFM, WSPR and FT8, and can even launch and track their own satellites.

To receive, the SimTX app runs a local rtl_tcp bridge, so SDR++ or any other rtl_tcp-capable SDR program can tune the simulated band as if it were an RTL-SDR, without any real radio hardware. The app runs on Windows, macOS, and Linux, and accounts are created via Discord. The software does not appear to be open source. The demo video below shows a song broadcast from a simulated Amsterdam and received 1145 km away in Budapest.

This may be useful for playing around with and seeing what different TX/RX variables and propagation effects do to signal reception.

We broadcast a song through a simulated ionosphere

DXLens: An iOS App Combining Shortwave Schedules, Propagation Data and Public SDRs

Thank you to Muayyad for sharing news about the release of his iPad/iPhone-compatible application, 'DXLens', designed for listening to remote shortwave SDR receivers. DXLens also comes with features like aggregated shortwave schedules from multiple sources, and propagation data and reception forecasting to help users choose the right global receiver for the conditions. He writes:

DXLens is a newly released iPhone/iPad application built around connecting the shortwave schedule and SDR listening workflows.

A listener can begin with a broadcast from EiBi, Aoki/NDXC, or HFCC, inspect the schedule-source evidence and transmission path, review modeled propagation context and assumptions, and then request compatible public SDR receivers for the frequency.

From there, DXLens provides a native listening workspace with live spectrum and waterfall, frequency/mode/bandwidth controls, receiver switching and reconnection, SDR presets, signal/session information, and local recording.

The app also includes Path Atlas, ionospheric and space-weather context, RF Environment tools, Model Audit, alerts, Custom listening views, and a structured reception logbook.

An important design boundary is that scheduled activity, propagation modeling, public receiver availability, and actual reception are kept separate rather than being presented as equivalent evidence.

The app appears to connect to the KiwiSDR network, and also has support for personal rtl_tcp based receivers.

At the moment, the app appears to be free, with no in-app purchases. DXLens is available on the Apple App Store.

DXLens Screenshots
DXLens Screenshots

Wavelingo: Real-Time AI Shortwave Translation for the KiwiSDR Network

Thank you to Christophe (F4DAN) for writing in about his new project called Wavelingo, an AI real-time shortwave radio translator. The software currently works with the KiwiSDR web SDR network. Christophe has a live public example running at wavelingo.app, however, with a 60-second timeout due to hosting cost constraints. Christophe writes:

Are you listening to a QSO in a foreign language on your transceiver? Click on the closest SDR (KiwiSDR fleet for now, more SDR to come in the future), and get real-time translations.

I opened a telegram channel to share updates and feedbacks on this projects - and provide support.

The software is open source, with the code available on GitHub.

Wavelingo - Real time AI translationfor shortwave radio stations received via the KiwiSDR network.
Wavelingo - Real-time AI translation for shortwave radio stations received via the KiwiSDR network.

RadioWorld Magazine Article about Software Defined Radios for Shortwave Listening

The latest August edition of the RadioWorld Magazine has included an article by James Careless about the use of software defined radios for shortwave radio listening. RadioWorld is a magazine targeted towards radio broadcast owners, managers and engineers all over the world. The article explores SDRplay and RTL-SDR Blog V4 units from the perspective of a shortwave listener new to software defined radios, comparing them to his high-end Sangean ATS-909X2 shortwave digital receiver.

The article can be accessed freely from this link and is found on pages 18-21.

First page of the RadioWorld Magazine article on SDRs.
First page of the RadioWorld Magazine article on SDRs.

The SDRSharp ListenInfo Plugin

SDR# is a popular software defined radio program that is compatible with RTL-SDR, Airspy and several other SDR devices. One feature is the ability for third parties to develop plugins for the software.

One recently released plugin that is gaining popularity is the "ListenInfo" plugin. The ListenInfo plugin uses a publicly available database of shortwave stations to display frequency station info for the LW, MW, SW bands within the SDR# spectrum display.

If you've ever been browsing the shortwave bands and wondered where a station is broadcasting from, and what it's transit power, beam direction and transmit schedule are like, then this will be a very useful plugin for you.

SDR# ListenInfo Plugin
SDR# ListenInfo Plugin

Video on Receiving HF Signals with the RTL-SDR Blog V3

Over on YouTube TheSmokinApe has uploaded a video showing how to use the direct sampling mode on RTL-SDR Blog V3 devices to receive HF transmissions, such as the ham bands, short wave and AM broadcast. In the video he shows how to activate direct sampling mode in SDR#, and then goes on to show reception of a few HF signals.

We note that an appropriate HF capable antenna is required to receive HF signals. The multipurpose dipole kits we sell are for VHF/UHF reception only. A simple and low cost HF antenna could just be a long wire running through your house.

HF Ham Radio with RTL-SDR Made EASY!

TechMinds: Testing the GA-450 Portable HF Active Loop Antenna

Over on the Techminds YouTube channel, Matt has uploaded his latest video which is a review of the GA-450 portable HF active loop antenna. The antenna costs between US$60-$80 + shipping and is available on Chinese market sites like Aliexpress and Banggood. It's advertised as covering 2.3 - 30 MHz, and uses a very portable and sturdy 20cm stainless steel loop. The active base amplifier is powered via a USB-C connector, and it even has a built in lithium battery for portable field use.

In his review Matt shows the antenna in action, noting that it's performance is quite a lot better than expected for it's small size, but it can't compare to his large half-wave end fed antenna. He notes that it appears to work best from 7 - 21 MHz, but not so well below 7 MHz. Overall he recommends it if you're looking for a small sized loop antenna.

GA-450 Portable Active Small Loop HF Antenna