Article / Software Defined Radio

SDR Software Options: Thetis, ZeusSDR & AetherSDR

N6MUD practical guideRadio / Software / Audio

Start with the radio you own, then choose the software that fits the way you operate.

For an N6MUD reader exploring ESSB, the transmit audio controls are an obvious attraction. But radio compatibility, operating system, and the connections to your other station tools deserve attention before EQ. These three projects serve different hardware and operating needs; they are not interchangeable clients for every SDR.

Official sources checked October 13, 2026. This is a source-based overview, not a comparative on-air test. Features and downloads can change.

01 / Apache Labs and HPSDR

Thetis

Thetis is a desktop SDR console in the OpenHPSDR family; the ramdor repository focuses on Apache Labs radios. It may suit an operator who wants detailed audio controls and connections to external station applications.

The official Thetis releases list v2.10.3.15 as the latest release when checked, with a Windows x64 MSI installer. The v2.10.3.13 notes document 5-, 10-, and 18-band parametric TX/RX EQ, adjustable Q, audio and I/Q streaming over TCI, and a redesigned recording/playback system. Those are useful areas to explore for voice processing and station integration.

Hermes Lite 2 download option: use the MI0BOT Thetis for Hermes Lite 2 downloads for the HL2-specific build. Its release notes say the main ANAN Thetis build is not HL2-aware. The HL2 version can be installed without the main Thetis release and does not overwrite an existing installation. Back up your databases and follow the release notes for keeping HL2 and ANAN databases separate.

Read the upgrade instructions for your starting version: the notes call for a database backup when moving from a version older than v2.10.3.13 and describe a database update. Confirm your radio and firmware match the chosen build.

Development statusThe release notes retain an announcement that public releases would stop. A newer July 2, 2026 update in the official repository README says development resumed for remote operation. Treat those remote features as planned work, rather than assuming they are in the downloadable release.

02 / An integrated HPSDR console

ZeusSDR

ZeusSDR’s official site describes a station console for OpenHPSDR Protocol 1 and Protocol 2 radios, using WDSP for signal processing. Desktop downloads are offered for Windows, macOS, and Linux, with a mobile web app that pairs with a Zeus Server. The station engine is open source; the client is proprietary.

It may suit operators who want audio processing and station tools together. Listed capabilities include a 10-band EQ, compression, off-air audio preview, integrated FT8/FT4 and FreeDV, logging, and Protocol 2 PureSignal. For a local audio example, see the N6MUD Zeus EQ settings and transmit profile.

Check the hardware notes closely. The site reports Hermes-Lite 2 transmit verification for FM and TUNE; G2/G2 MkII receive and carrier-transmit checks, with PureSignal convergence on G2 MkII; and receive verification for ANAN-100D/Angelia. It says Hermes, Metis, and older ANAN boards are not yet wired up. Protocol support alone is not a promise that every radio or mode has been verified.

03 / A workstation for FlexRadio

AetherSDR

AetherSDR’s official site presents an independent, GPLv3 open-source workstation for FlexRadio 6000, 8000, and Aurora transceivers. It offers native Linux, macOS, and Windows builds, and identifies v26.10.2 as its latest release when checked.

It may suit a FlexRadio operator looking for a native desktop workflow with audio and station integration. The site lists GPU-rendered spectrum and waterfall displays, multiple slices and detachable panadapters, an RX/TX processing strip with EQ, compression and de-essing, DAX audio/IQ connections for digital-mode applications, and SmartLink remote operation.

Firmware matters: the stated active test target is a FLEX-8600 running firmware 4.2.18. The site says earlier 4.x firmware works and 3.x is unsupported. Check its download section for your platform’s package. Some noise-reduction options are platform-specific, including NVIDIA BNR and macOS MNR; do not assume identical processing choices on every computer.

04 / Match the station first

Where to start

Use this as a shortlist based on the projects’ documented scope, rather than a ranking of audio quality or reliability.

Your starting point	Explore	Check first
Apache Labs station on Windows	Thetis	Build, firmware, and database migration notes.
Supported HPSDR radio; integrated tools	ZeusSDR	Model-specific receive and transmit verification.
FlexRadio station; native desktop client	AetherSDR	Radio firmware and platform-specific features.

Once compatibility is settled, compare the work you do every day: microphone routing, saving a voice profile, recording receive audio, and connecting your preferred logging or digital-mode tools. For ESSB experiments, keep a known-good profile and change one stage at a time so you can hear what each adjustment does.