spectrogram — ONED signal op

• 資料種類:signal → image2d

• 呼叫: import fullseye as fs; fs.ledger.spectrogram(x, rate=1.0, win=256, hop=None)(要直接呼叫實作,import dsp; dsp.spectrogram(x, rate=1.0, win=256, hop=None);從台帳取用則 ops1d.get("spectrogram"))

• 經台帳呼叫的回傳值: fullseye.ledger.spectrogram(...) 只回傳**宣告的 out 型別 image2d 的值**(底層函式還會回傳輔助資訊)。需要被捨棄的部分時,請用 fullseye.ledger.spectrogram.raw(...),或直接呼叫 dsp.spectrogram。

• 底層回傳: (freqs, times, S) — S が本体

用法

> 該運算子的說明尚無譯文,以下照原文給出。

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.

參考(範例資料・文獻)

• 範例資料目錄(下載 URL / 授權) —— 2-D 用 skimage.data(BSD/公有領域)加合成圖,3-D 給出真實資料源(Stanford/PDS 等)的下載 URL。

• 運算子來歷與參考文獻 —— 該運算子族所依據的研究/方法出處。

• 演算法的正典(作者・年份)與用途見上面的族使用指南。

可執行的範例(實際呼叫該運算子並已驗證的樣例)

• acoustic_condition_monitoring — py -3.11 examples/acoustic_condition_monitoring.py

型別可銜接的下一個運算子(可接受 image2d 作為輸入)

—

同類別(signal)

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

*Provenance: dsp.py — ONED 運算子登記表。本條目由 tools/opdocs.py md 自動產生(請勿手動編輯)。*

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