spectrogram — ONED signal op

• 数据种类:signal → image2d

• 调用: import fullseye as fs; fs.ledger.spectrogram(x, rate=1.0, win=256, hop=None)(要直接调用实现,import dsp; dsp.spectrogram(x, rate=1.0, win=256, hop=None);从台账取用则 ops1d.get("spectrogram"))

• 经台账调用的返回值: fullseye.ledger.spectrogram(...) 只返回**声明的 out 类型 image2d 的值**(底层函数还会返回辅助信息)。需要被丢弃的部分时,使用 fullseye.ledger.spectrogram.raw(...),或直接调用 dsp.spectrogram。

• 底层返回: (freqs, times, S) — S が本体

用法

> 该算子的说明尚无译文,以下照原文给出。

STFT magnitude spectrogram -> `(freqs, times, S) with S` shape

`(n_freqs, n_frames). Hann-windowed; *hop* defaults to win//2`.

**Same raw convention as :func:spectrum, but a different divisor.** Each

column is the unnormalised `|rfft(frame * hann(win))|`, so it is not an

amplitude either — and dividing by `2/win` is *wrong* here, because the

Hann window has already thrown away part of the signal. The correct one-sided

amplitude conversion divides by the window's coherent gain::

w = np.hanning(win)

amp = S * (2.0 / w.sum()) # bins 1 .. win/2-1; DC / Nyquist: 1/w.sum()

Measured on a unit sine at a bin centre (`rate = 16000` Hz, 1000 Hz,

amplitude exactly 1.0, `win = 256`): the raw column peak is

`63.7497786196906; * 2/win gives 0.49804514546633283` (too small by

exactly the Hann coherent gain `sum(w)/win = 0.498046875`), while

`* 2/sum(w) gives 0.9999965273676957`. Only the second one is the

amplitude that was actually in the signal.

Peak *positions*, frame-to-frame ratios and any dB *difference* are unaffected

by either factor. This function returns magnitudes only — the phase is

discarded, so it cannot be inverted; use `acoustics.stft / acoustics.istft`

for a round-trip.

参考(示例数据・文献)

• 示例数据目录(下载 URL / 许可证) —— 2-D 用 skimage.data(BSD/公有领域)加合成图,3-D 给出真实数据源(Stanford/PDS 等)的下载 URL。

• 算子来历与参考文献 —— 该算子族所依据的研究/方法出处。

• 算法的正典(作者・年份)与用途见上面的族使用指南。

可运行的示例(实际调用该算子并已验证的样例)

• acoustic_condition_monitoring — py -3.11 examples/acoustic_condition_monitoring.py

类型可衔接的下一个算子(可接受 image2d 作为输入)

—

同类别(signal)

lowpass · highpass · bandpass · envelope · rms · local_std · quantize · companding_mu_law

*Provenance: dsp.py — ONED 算子登记表。本条目由 tools/opdocs.py md 自动生成(请勿手工编辑)。*

© 2026 Kazufumi Furuse — Fullseye operator documentation. Licensed under Apache-2.0.