MoonSpectrum

MoonSpectrum 是一个面向 MoonBit 生态的科学信号处理基础库。它提供复数运算、DFT/FFT、频谱分析、窗函数、卷积、基础 FIR 滤波和命令行分析工具，目标是补齐 MoonBit 在传感器数据、实验数据、振动信号、周期信号和教学验证中的基础算法能力。

本项目不做音频播放、采集或设备后端，也不依赖 native FFI。当前版本优先保证算法清晰、测试可复现、跨后端可运行，后续再扩展 STFT 谱图、IIR 滤波、Welch PSD、重采样和 WebAssembly 可视化。

Why

MoonBit 已经有一些音频、图形、矩阵和工程工具包，但通用科学信号处理方向还缺少一个小而稳的基础库。MoonSpectrum 的定位是：

• 给 MoonBit 项目提供可复用的 FFT、频谱、窗函数、卷积和基础滤波能力。
• 给 OSC2026 评审提供可直接运行的测试、示例数据和 CLI。
• 给后续生态扩展留下清楚边界，而不是把音频引擎、数据框、可视化和控制系统混在一起。

Features

• Complex 复数类型：加减乘、缩放、幅值、近似比较。
• DFT / radix-2 FFT / inverse FFT。
• 幅度谱、功率谱、频率 bin、主频检测。
• 信号生成：正弦波、方波、脉冲、线性 chirp、确定性白噪声。
• 窗函数：Rectangular、Hann、Hamming、Blackman。
• 卷积：线性卷积、循环卷积。
• 基础滤波：移动平均、FIR 卷积滤波、低通/高通窗函数法 taps。
• CLI：demo、fft、analyze、window、convolve。

Quick Start

moon test
moon run cmd/main -- demo
moon run cmd/main -- fft examples/sine.csv --sample-rate 8
moon run cmd/main -- analyze examples/sine.csv --sample-rate 8
moon run cmd/main -- window hann 4
moon run cmd/main -- convolve examples/sine.csv examples/kernel.csv

Typical output:

{"samples":8,"sample_rate":8,"dominant_bin":2,"dominant_frequency":2,"magnitude":4}

API Sketch

test {
  let signal = sine_wave(length=8, sample_rate=8.0, frequency=2.0)
  let spectrum = fft(real_signal(signal))
  let peak = dominant_peak(spectrum, 8.0)
  inspect(peak.index, content="2")
}

The root package exports the public API. CLI code lives in cmd/main and uses the same library functions as users would.

Project Layout

• complex.mbt - complex arithmetic and approximate comparisons.
• fft.mbt - DFT, FFT, inverse FFT, real signal conversion.
• analysis.mbt - spectra, frequency bins, peak detection.
• signals.mbt - test/demo signal generation.
• windows.mbt - window functions and window application.
• convolution.mbt - linear and circular convolution.
• filters.mbt - moving average, FIR filtering, low/high-pass taps.
• cmd/main - CLI entry point.
• examples - small CSV fixtures for smoke tests.
• docs/competition - OSC2026 proposal and acceptance material.

Verification

moon info
moon fmt --check
moon check --warn-list +73
moon test
powershell -ExecutionPolicy Bypass -File scripts\verify_acceptance.ps1 -SkipPublishDryRun

Release Links

• GitHub: https://github.com/chgttyyr/MoonSpectrum
• GitLink: https://gitlink.org.cn/chgttyyr/MoonSpectrum
• Mooncakes: https://mooncakes.io/docs/chgttyyr/MoonSpectrum

MoonSpectrum is published as the Mooncakes module chgttyyr/MoonSpectrum@0.1.0. The moon.mod file is the source of truth for the package metadata shown on Mooncakes.

Current Boundaries

• FFT currently requires power-of-two input length.
• CSV parser intentionally handles simple single-column numeric fixtures.
• Time zones, timestamps, streaming IO, STFT, IIR, and visualization are future work.
• No native FFI is used in v0.1.0.

Roadmap

• STFT and spectrogram data export.
• Welch PSD and cross-correlation.
• IIR biquad filters.
• Resampling and interpolation helpers.
• Browser/WebAssembly demo for frequency-domain visualization.
• More robust CSV/JSON data pipeline.

License

Apache-2.0.