Crate radio_utils_emu 

OpenHPSDR Protocol-1 hardware emulator.

Speaks the Hermes / Hermes Lite 2 wire format end-to-end over UDP, so the rest of the workspace (and third-party clients like Thetis, deskHPSDR, the web client) can be developed and tested without real hardware. The CLI binary lives in src/main.rs — cargo run --release -p radio-utils-emu -- --radio hermeslite --echo-live is the standard “virtual band” launch.

Echo modes

radio::EchoMode selects how the emulator handles transmitted IQ:

• Live — the bounded per-frequency LiveBuffer mixes concurrent TXers additively at a real-time write head (feed_from(client_id, samples)) and plays back to listeners with a ~21 ms delay (LIVE_DELAY in radio.rs). Two operators keying simultaneously on the same frequency superimpose like real co-channel signals (QRM); the buffer fills at 1× real-time regardless of how many TXers are active. This is the mode used by hosted multi-user “virtual band” deployments.

• Loop — TX is recorded into the per-frequency FreqRecorder, trimmed of leading/trailing silence on commit, padded with LOOP_TAIL_SILENCE_SEC (currently 500 ms) of silence so each iteration is audibly separated, then loops forever with a 40 ms head/tail crossfade. The recording persists across PTT cycles within a LOOP_SESSION_GAP window (currently 30 s): a slow CW operator who keys “C”, pauses, then keys “Q” gets both letters with the actual inter-cycle silence preserved in the loop, instead of the second cycle overwriting the first.

• None — no echo; RX delivers signal-generator noise only.

Multi-client model

Each Protocol-1 client connection (identified by SocketAddr) gets its own client_task running an tokio::time::interval at the wire packet cadence (1024 Hz typical). The MAX_CLIENTS cap is configurable via protocol1::DEFAULT_MAX_CLIENTS (32) and can be overridden per process through the binary’s --max-clients flag.

Live-mode TX from N clients on one freq mixes additively: each call to radio::EchoBuffer::feed dispatches to LiveBuffer::feed_from which writes additively at the client’s tracked offset. (The client_id parameter on feed is only consulted in live mode.) Loop mode falls back to a single shared append buffer per freq — fine for the typical single-operator-at-a-time use case; concurrent loop-mode TX is not mixed correctly.

Modules

protocol1

radio