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mySdrPlayback: MacOS Software for Browsing Through IQ Recordings from SDR#, SDRUno and More

mySdrPlayback is a program for MacOS that allows you to easily browse through IQ recordings created from multiple SDR programs. Recently the software's author (@ChrisSmolinski) 
Tweeted that he's added support for SDR# and SDRUno IQ recordings
. The program is described below:

Why use this app? It makes it easy to slog through lots of recording files, looking for interesting signals. Load a file, and a waterfall for the entire file is created. You can scroll around, and if you see anything that looks interesting, you can drag select it, and then demodulate it. You can even save the demodulated audio as a WAVE file, that you can listen to later, send to someone else, or play into your digital decoding software, if it is an RTTY, SSTV, etc. transmission.

Support for other SDR recording file formats is possible, you'll need to work with me by providing sample files and details on the format. This program is presently for macOS only. Support for Windows may happen... stay tuned!

mySdrPlayback now supports SDR# and SDRUno IQ Files.
mySdrPlayback now supports SDR# and SDRUno IQ Files.

LocalRadio: A new RTL-SDR App for MacOS

Thanks to Doug Ward (@dsward) for letting us know about his new RTL-SDR compatible MacOS based app called LocalRadio. LocalRadio is an open source web browser based app that connects to a MacOS server running an RTL-SDR. The software allows you to listen in on any frequency supported by the RTL-SDR in AM or FM modes, and audio is capable of being streamed to multiple devices via a built the LAME MP3 encoder, EZStream and Icecast server. It does not provide an FFT or waterfall display however.

The software introduction reads:

LocalRadio is an experimental, GPL-2 licensed open-source application for listening to “software defined radio” on your Mac and mobile devices. With an inexpensive RTL-SDR device plugged into the Mac’s USB port, LocalRadio provides a casual listening experience for your favorite local FM broadcasts, free music, news, sports, weather, public safety and aviation scanner monitoring, and other radio sources.

LocalRadio’s easy-to-use web interface allows the radio to be shared from a Mac to iPhones, iPads, Android devices, and other PCs on your home network. No additional software or hardware is required for sharing with mobile devices, simply use the built-in mobile web browser to connect to LocalRadio and tune to your favorite stations. You can also listen to LocalRadio audio on your Apple TV and other AirPlay-compatible devices.

LocalRadio does not provide features like FFT waterfalls, panadapters, or signal recording that are found on other SDR software. For those features, GQRX for Mac is highly recommended. GQRX is a good way to discover radio frequencies that can be used with LocalRadio.

LocalRadio is intended for use as in-home entertainment, using a local area network with a private IP address. It has not been tested with a public IP address, particularly for security testing, therefore it is not recommended for that purpose. For simply listening to LocalRadio on the Mac with the RTL-SDR device plugged in, no network is required at all.

LocalRadio Interface in the Safari Web Browser
LocalRadio Interface in the Safari Web Browser

A New Meteor M LRPT Image Decoder for Windows, Linux, MacOS and Raspberry Pi

Thanks to twitter user @LinuxSocist for submitting a link to this new Meteor M weather satellite LRPT decoder called ‘meteor_decoder’ which can be run on both Linux and Windows. Pre-built binary of the software for Windows, Linux Raspberry Pi and MacOS are available at

This software decoder appears to be an excellent choice for those people who want to perform their reception and decoding of Meteor M satellites all in Linux. Previously as explained in this previous post, you were able to receive the QPSK data in Linux with an RTL-SDR and a GNU Radio program, but then you’d still need to boot into Windows or run Wine to run LRPTofflinedecoder in order to generate the image. Now it appears that the image generation can be performed natively in Linux too with meteor_decoder. This help with creating portable automated Raspberry Pi based Meteor M decoder servers.

Meteor M is a class of Russian weather satellites that transmit live weather images of the earth as they pass over your location. They are somewhat similar to the NOAA satellites, although the Meteor satellites transmit higher quality images via a digital LRPT signal, rather than the analog APT signals used by NOAA. With an RTL-SDR, an appropriate antenna and decoding software they can easily be received.

An Example LRPT Image Received with an RTL-SDR from the Meteor-2 M2.
An Example LRPT Image Received with an RTL-SDR from the Meteor M-N2 Satellite.

An RTL-SDR Receiver App Written in Swift for MacOS

Over on YouTube user GetOffMyHack has uploaded a video that shows his development of a Mac based general purpose tuning app for the RTL-SDR, which was written in the Swift programming language. Swift is a programming language which is designed for creating apps for a wide range of smart Apple devices.

GetOffMyHack’s program currently has a spectrum and waterfall view, can tune to any frequency, demodulate NFM and AM, and it also has a built in CTCSS decoder. At the moment the software and code is unreleased, but he writes that in the future the code will be released and made open source once he reaches the next version in the development cycle. Keep an eye on his YouTube channel for any updates.

MacOS Desktop RTLSDR Application written in Swift

New Oregon Scientific Temperature/Humidity Data Receiver Software for MacOS and RTL-SDR

Recently programmer Erik Larsen wrote in to us to let us know about a MacOS application he has been developing to receive temperature and humidity data from Oregon Scientific v2.1 sensors. Oregon Scientific manufactures popular electronic weather stations that transmit data from remote sensors wirelessly. Using an RTL-SDR and Eriks software it is possible to receive the weather station data on a Mac computer and display the data on a GUI. The software can be downloaded from the releases section on its GitHub page.

Note that there are also several Linux based Oregon Scientific decoders available including rtl-433m-sensor, rtl_osv21, and rtl-wx.

Oregon Weather Decoder
Oregon Weather Decoder

SDR++ Version 1.0.0 Released

SDR++ is an open source, cross platform, C++ based GUI general receiver program for various SDRs including the RTL-SDR. Since it's alpha release in mid 2020, it has undergone huge amount of development, and is quickly becoming the main program of choice for many users due to it's efficiency, cross platform and multi-SDR hardware support and increasing feature set. And with an easy GUI very similar to that of SDR#, it's easy for most users to learn.

Recently version 1.0.0 of the SDR++ software has recently been released. This is the first non-beta stable version, so represents a major milestone in development. Over on Reddit programmer u/xX_WhatsTheGeek_Xx summarizes the latest developments.

After over a year of work, I'm proud to released version 1.0.0 of SDR++!

For those who don't know, SDR++ is a crossplatform (Windows, Linux, MacOS, BSD) and open-source ( general purpose receiver software meant to be simple and easy to use. It has advances features like multi-vfo and uses a fully custom DSP making it very efficient.

Here are the following additions compared to the last version:

  • Support for the SpyServer protocol
  • Support for all SDRplay devices
  • Support for all BladeRF devices
  • Support for all LimeSDR devices
  • Optional IQ correction
  • Optional Decimation
  • Broadcast FM Stereo
  • Frequency manager to create lists of frequency and optionally display them directly on the FFT/Waterfall
  • Network sink to stream the audio output via TCP or UDP
  • Options to set the FFT framerate, FFT size and FFT window.
  • Theming with Dark and Light themes supplied by default
  • RigCTL server module to control SDR++ from, for example, gpredict.
  • A bunch of keyboard shortcuts (see wiki on the github page)
  • SNR meter
  • More info when hovering a VFO
  • Colored VFOs to easily identify which is which at a glance
  • Meteor M2 demodulator compatible with LRPTOfflineDecoder and Satdump
  • Ability to resize VFOs by directly dragging the sides on the FFT and waterfall
  • Module manager to easily add or remove any module on the fly without having to restart or edit the config manually
  • File dialogs to select directories in the recorder or files in the file source (instead of having to type in the path)
  • Ability to disable modules that support it (Radio and Meteor M2 demodulator) with one click (to save CPU power or just if they're not needed)
  • Lots of performance improvements
  • Ludicrous amounts of bugfix :)

I'd like to thank the many contributors, patrons and companies (SDRplay, Airspy, Nuand, LimeMicro) who helped make this project possible!

If you have any issue with the software, please open a github issue or contact me directly on the SDR++ discord (see readme on github)

I hope this software comes in useful to at least some of you ;)

We also wanted to highlight the fact that SDR++ runs smoothly with about 50% CPU usage on a Raspberry Pi 4 with an RTL-SDR.

Also according to @cemaxecuter who created DragonOS, if rtaudio is installed on Linux , then an easy to use virtual audio sink becomes usable from SDR++, allowing audio to be easily passed to other programs such as WSJT-X just like on Windows.

A ready to use zip file for Windows is available on the GitHub Releases page, as well as amd64 .deb and .pkg install files for Ubuntu, Debian and MacOS systems. For other systems the compilation instructions are available on the readme or Git main page.

SDR++ V1.0.0 Screenshot

SuperSDR: A KiwiSDR + CAT Client for Ham Radio

Thank you to Marco (IS0KYB) for informing us about the release of his new software called "SuperSDR". SuperSDR allows you to easily synchronize frequency tuning with a remote KiwiSDR via a CAT connection to a standard ham radio. The KiwiSDR is a 14-bit wideband RX only HF SDR which has up to 32 MHz of bandwidth, so it can receive the entire 10 kHz - 30 MHz spectrum all at once.

It allows to use a remote KiwiSDR along with a local (or even remote) standard radio in sync. It works on Linux, Windows and MacOSX.

The main purpose is to have an interactive panadapter that is not forcibly tied to our local antenna, but allows one to try any combination of CAT radio / SDR. I'd like to implement a remote KiwiSDR selection interface to choose the best SDR for the purpose.

I'm still developing it, and it is not complete feature-wise, but it is ready to be used.

Somebody asked me if it would be possible to integrate a RTL-SDR into it and I plan to do that using the old PEPYSCOPE project code [covered in a previous post].

The video below shows a slightly older version of SuperSDR in action.

SDR-Server: An Advanced Open Source RTL-SDR Streaming Server

Developer @dernasherbrezon has recently released a new program called "sdr-server" which is a streaming server. Unlike the more basic rtl_tcp server, sdr-server has some more advanced features like being able to serve multiple clients a slice of the bandwidth simultaneously. When compared to SpyServer, another advanced RTL-SDR compatible streaming server, sdr-server has similar features, however, sdr-server is open source. Some of the key features include:

  • Share available RF bandwidth between several independent clients:
    • Total bandwidth can be 2016000 samples/sec at 436,600,000 hz
    • One client might request 48000 samples/sec at 436,700,000 hz
    • Another client might request 96000 samples/sec at 435,000,000 hz
  • Several clients can access the same band simultaneously
  • Output saved onto disk or streamed back via TCP socket
  • Output can be gzipped (by default = true)
  • Output will be decimated to the requested bandwidth
  • Clients can request overlapping RF spectrum
  • Rtl-sdr starts only after first client connects (i.e. saves solar power &etc). Stops only when the last client disconnects
  • MacOS and Linux (Debian Raspberrypi)
How bandwidth slices can be shared with sdr-server.