Replace the per-sample ring-buffer FIR convolution with block-level
overlap-save convolution using rustfft. For a block of M samples and
N taps the old approach costs O(N·M); the new one costs O(M log M),
with rustfft using SIMD (AVX2/SSE4) internally.
Key changes:
- Add rustfft = "6" dependency
- Add BlockFirFilter: overlap-save filter with pre-computed H(f) and
a single forward+inverse FFT pair per block (no per-sample multiply)
- ChannelDsp.process_block() now:
1. Batch-mixes entire block to baseband in one vectorisable loop
2. Applies BlockFirFilter to I and Q (one FFT pair each)
3. Decimates and demodulates as before
- Keep the old FirFilter for unit tests (sample-by-sample interface)
- Add BlockFirFilter unit tests (DC passthrough, length preservation)
- IQ_BLOCK_SIZE promoted to pub const for use in filter sizing
For the default config (4096-sample blocks, 64 taps, decim=40):
Old: ~262144 multiply-adds per FIR × 2 components = ~524k per block
New: ~2 × (3 × 8192 × log2(8192)) ops, all SIMD-vectorised by rustfft
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Signed-off-by: Stan Grams <sjg@haxx.space>
Drop optional feature gating - SoapySDR hardware support is now required.
Make soapysdr a required dependency in Cargo.toml instead of optional.
Update server to always enable soapysdr backend and its dependencies.
Simplify initialization to always use RealIqSource instead of conditional
fallback to MockIqSource.
This assumes SoapySDR library is installed on the system.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Introduces the trx-backend-soapysdr crate with a compilable SoapySdrRig
struct that satisfies the Rig + RigCat trait bounds. RX methods
(get_status, set_freq, set_mode, get_signal_strength) are implemented;
TX-only methods return RigError::not_supported. as_audio_source returns
None for now (overridden in SDR-07). Wires the crate into the workspace
and trx-backend (feature "soapysdr"), and fixes the non-exhaustive match
on RigAccess::Sdr in trx-server main.rs and rig_task.rs.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Signed-off-by: Stan Grams <sjg@haxx.space>
sjg
