station-engine

station-engine is a headless OpenHPSDR station process for Protocol 1 and Protocol 2 radios. It provides radio transport, DSP, transmit control, local audio, band logic, safety services, and a versioned HTTP/WebSocket station protocol. It does not include a user interface.

The source is maintained by Douglas J. Cerrato (KB2UKA) and Christian Suarez (N9WAR).

License

An engine distribution without the optional ASIO host bridge is conveyed under the GNU General Public License, version 3 or (at your option) any later version. A Windows distribution containing the Steinberg ASIO SDK-derived bridge is conveyed under GPL-3.0-only, because the SDK's GPL version 3 option does not include an "or later" grant. The full version 3 text is in LICENSE, which also states the scope summarised here; provenance and per-component attribution are in ATTRIBUTIONS.md; third-party components and their preserved license texts are inventoried in THIRD-PARTY-NOTICES.md.

Most first-party engine code is licensed GPL-2.0-or-later, and those files individually remain available under that license; the version 2 text is in LICENSE.GPL-2.0. The SPE Expert 1.5K Taurus amplifier support under Station.Engine.Hosting/SpeTaurus/ is GPL-3.0-or-later (its provenance is recorded in Station.Engine.Hosting/SpeTaurus/SOURCE.md). The "or later" option on the GPL-2.0-or-later portions permits both engine compositions. Individual source files retain their stated licenses.

This repository is the complete corresponding source for the station engine binary distributed with Zeus SDR. Each release tag here matches the engine shipped in the corresponding Zeus release.

Windows artifacts containing zeus_asio.dll fail packaging unless the public source tag is exactly v<engineVersion> and already exists. This rule also applies to dev builds; a pointer to the latest stable source is not accepted for an ASIO-bearing artifact. Non-Windows dev builds, which do not convey ASIO, retain the existing stable-source pointer and exact per-native source pins.

Native libraries

The native source used by the station engine is included under native/: Zeus-modified WDSP, its statically embedded libspecbleach and RNNoise sources, miniaudio, the GPL-3.0-only ASIO 2.3.4 host bridge and SDK-derived source, the pinned codec2 fetch recipe and patch, and the RADE build glue, shim, exact materialized upstream slices, integrity record, and binary/source binding. Artifact-to-source mapping and the exact per-platform build commands are in NATIVE-BUILD.md. The proprietary VST3 and Audio Unit bridge binaries are not part of the station engine and are not included; the published tree builds against Zeus.Plugins.VstHostStub instead.

Station.AudioRing is first-party code additionally published under the MIT license so it can be reused outside Zeus. Third-party components carry their own licences — see THIRD-PARTY-NOTICES.md.

The Zeus SDR client that drives this engine is a separate, proprietary program communicating over the loopback station protocol documented below. It is not part of this repository and is not covered by this license. ASIO SDK-derived source and binaries do not enter that product.

Trademarks

ZeusSDR™ and Zeus™ are trademarks of the Zeus project maintainers. The engine's GPL licences cover its source code; they grant no right to use those names, logos, or branding for a modified or derivative product. This is the ordinary separation of copyright from trademark, not an added GPL restriction. See TRADEMARK.md for the full policy.

Requirements

• .NET 10 SDK
• macOS, Windows, or Linux on a supported .NET architecture

The checked-in runtime directories provide the native libraries used by the supported release targets. Raspberry Pi and other Linux ARM64 systems use the linux-arm64 runtime assets.

Build

From the repository root:

dotnet restore StationEngine/StationEngine.csproj
dotnet build StationEngine/StationEngine.csproj

Run

The engine requires a loopback TCP port:

dotnet run --project StationEngine/StationEngine.csproj -- --port 6060

For a published native executable, pass the same argument directly:

./StationEngine --port 6060

On Windows, run StationEngine.exe --port 6060.

The process listens only on 127.0.0.1. A successful startup exposes protocol discovery at http://127.0.0.1:6060/api/station/version.

Station Protocol v1

The implementation is the authoritative protocol reference:

• Station.Engine.Hosting/StationProtocolEndpoints.cs defines version discovery.
• Station.Engine.Hosting/StationEngineEndpoints.cs registers the HTTP and WebSocket surface.
• Station.Engine.Hosting/StreamingHub.cs implements /ws framing and session behavior.
• The contracts project defines binary frame layouts, message identifiers, DTOs, and wire helpers.