order opsignal → tableimport fullseye as fs; fs.ledger.angular_resample(x, rate, rpm, samples_per_rev=64) (実装を直接呼ぶなら import acoustics; acoustics.angular_resample(x, rate, rpm, samples_per_rev=64)、台帳から引くなら opsacoustics.get("angular_resample"))Resample a time record onto the shaft-angle axis (computed order tracking).
Under a changing shaft speed, a component locked to the shaft has a moving frequency and smears across the spectrum, while a structural resonance stays put. Resample the record so the samples are equally spaced in shaft angle instead of in time and the situation reverses exactly: the order becomes a single line and the resonance smears.
rpm is either a single number (constant speed — the transform is then a
pure rescaling) or a per-sample array on the same clock as the signal. The
cumulative revolution count is the trapezoidal integral of rpm/60, and
the signal is linearly interpolated onto a uniform grid in it.
Returns a dict — an angle-domain record is not put into circulation as a
plain signal, deliberately. Its samples are indexed by angle, not time, so
handing it to any op that takes a rate would produce frequencies in Hz
from an axis measured in revolutions: no exception, no NaN, just wrong
numbers. (Same judgement, and the same reason, as motionmag.motion_magnify
not exposing a bare video adapter.) The dict carries signal,
angle_rev, samples_per_rev, revolutions (total),
whole_revolutions, rate (the original time-domain one, for
provenance), mean_rpm, max_order.
max_order is samples_per_rev / 2 — the Nyquist of the angle axis.
Measured: a pure order-3.5 component on a 600 -> 1800 rpm ramp, resampled at 64 samples/rev over 78 whole revolutions, reads amplitude 0.999371 in a single bin of the order spectrum; the same component in the ordinary spectrum peaks at 0.070203 and is 66.5 Hz wide.
Raises ValueError: everything :func:_as_signal refuses, a
non-positive or wrong-length rpm, samples_per_rev outside
[2, 65536], an output over :data:MAX_ANGULAR_SAMPLES, fewer than one
complete revolution in the record, and — the aliasing refusal — a
samples_per_rev whose implied Nyquist order needs content above the
time-domain Nyquist. Asking for 64 samples/rev on a shaft turning at 30 Hz
means representing 960 Hz, which a 100 Hz recording does not contain; the
resampler would happily manufacture it from the interpolation.
py -3.11 examples/acoustic_condition_monitoring.pytable を入力に取れる)order)Provenance: acoustics.py — ACOUSTICS operator registry. この per-op ノートは tools/opdocs.py md が自動生成(手編集しない)。
© 2026 Kazufumi Furuse — Fullseye operator documentation. Licensed under Apache-2.0.