metrology.compliance

IEC 61260-1:2014 filter and IEC 61672-1:2013 weighting class verification.

Filters. Acceptance limits on relative attenuation transcribed from the official text (BS EN 61260-1:2014, Table 1, standard pages 15-16): octave-band breakpoint frequencies with class 1 and class 2 minimum/maximum limits. Fractional-octave-band breakpoints are derived with Formulas (9) and (10) (subclauses 5.10.3-5.10.4) and limits between breakpoints are interpolated linearly in lg(Omega) per Formula (11) (subclause 5.10.6). Relative attenuation is deltaA(Omega) = A(Omega) - Aref (Formula 8) with A = Lin - Lout (Formula 7); here Aref is the attenuation at the exact mid-band frequency (subclause 5.9: the pass-band reference attenuation).

IEC 61260-1:2014 defines only classes 1 and 2. Class 0 (the tightest, laboratory-grade class) lives only in the withdrawn IEC 61260:1995 / EN 61260:1995 Table 1 and its US twin ANSI S1.11-2004 Table 1, whose class 1/2 masks differ numerically from the 2014 edition (e.g. the 2014 pass-band reference tolerance is ±0.4 dB for class 1 vs ±0.3 dB in 1995, and the 2014 stop-band edge minimum is +1.2 dB vs +2.0 dB in 1995). The two editions are therefore kept as separate mask tables selected by the edition argument ("2014" default -> classes 1/2; "1995" -> classes 0/1/2). The 1995 / ANSI-2004 octave-band table was transcribed digit-for-digit and cross-checked between the two standards (they agree exactly).

Weightings. A/C/Z frequency-weighting acceptance limits transcribed from BS EN 61672-1:2013, Table 3 (standard page 22): the design-goal responses and the class 1 and class 2 upper/lower limits at the 34 nominal frequencies from 10 Hz to 20 kHz. A lower limit of -inf means only the upper limit applies (subclause 5.5.6 checks measured deviations at the nominal frequencies).

The historical B weighting is verified against ANSI S1.4-1983: design goals from the B column of Table IV (whose A and C columns equal IEC 61672-1:2013 Table 3 digit for digit) and tolerance limits from Table V, whose instrument Types 1 and 2 fill the class 1 / class 2 verdict slots (the stricter laboratory Type 0 mask is exercised by the CI conformance report). The AU weighting is verified against IEC 61012:1990: design goals are the sum of the nominal A response and the Table 1 nominal U response (with the subclause 2.2 explicit AU values at 25/31.5/40 kHz), checked against the Table 1 tolerances for the filter as a separate unit, the tighter of the two tolerance readings the standard offers. IEC 61012 publishes a single tolerance set, so both verdict slots carry the same margin for AU.

Auto-generated from the source docstrings by scripts/generate_api_docs.py (make api-docs). Do not edit by hand.

class_limits

class_limits(
    fraction: float,
    filter_class: int,
    omega: np.ndarray,
    *,
    edition: str = '2014',
) -> tuple[np.ndarray, np.ndarray]

Acceptance limits on relative attenuation at normalized frequencies.

Parameters

Name	Description
fraction	Bandwidth designator denominator b (1 for octave, 3 for one-third octave, …).
filter_class	Performance class: 1 or 2 for edition="2014"; 0, 1 or 2 for edition="1995".
omega	Normalized frequencies f/fm (> 0).
edition	"2014" (IEC 61260-1:2014, classes 1/2) or "1995" (IEC 61260:1995 / ANSI S1.11-2004, classes 0/1/2).

Returns: Tuple (minimum, maximum) relative attenuation in dB per point; the maximum is +inf outside the pass-band.

Note

The exact band-edge point Omega = G^(1/2) is treated as pass-band. The 1995 edition’s Table 1 prints a dedicated minimum (+2.3/+2.0/ +1.6 dB) at that single frequency, which this convention relaxes to the pass-band minimum; the discrepancy has measure zero — any continuous response violating the edge row is caught at edge + eps by the interpolated stop-band mask. The 2014 edition defines only the G^(1/2) - eps and G^(1/2) + eps rows, which the masks match exactly.

filter_class_compliance

filter_class_compliance(
    bank: OctaveFilterBank,
    *,
    num_points: int = 32768,
    edition: str = '2014',
) -> FilterComplianceResult

Verify a filter bank and package the verdict as a reportable result.

Runs verify_filter_class and stores the outcome together with the bank’s second-order sections, mid-band frequencies, per-band decimation factors and sampling rate, so the returned object can redraw the measured relative attenuation and render an accredited .report() fiche without keeping a reference to the bank.

Parameters

Name	Description
bank	The filter bank to verify.
num_points	Frequency grid points per band (>= 16).
edition	"2014" (IEC 61260-1:2014, classes 1/2) or "1995" (IEC 61260:1995 / ANSI S1.11-2004, adds the stricter class 0).

Returns: A FilterComplianceResult.

FilterComplianceResult

FilterComplianceResult(
    overall_class: int | None,
    bands: tuple[dict[str, Any], ...],
    fraction: int,
    edition: str,
    sos: tuple[np.ndarray, ...],
    band_frequencies: np.ndarray,
    factors: tuple[int, ...],
    fs: float,
    num_points: int,
    range_limited: bool = False,
)

IEC 61260-1 class-compliance verdict of an OctaveFilterBank.

Wraps the dictionary of verify_filter_class together with the minimal filter-bank data needed to redraw the measured relative-attenuation curve, so the result exposes the standard plot / report pair without holding a reference to the (possibly stateful) bank.

Attributes

Name	Description
overall_class	The strictest class every band meets (0/1/2), or None when at least one band meets no class of the edition.
bands	The per-band verdict dictionaries of verify_filter_class (one {"freq", "class", "margin_class<c>_db", ...} per band), as an immutable tuple.
fraction	Bandwidth designator b (1 for octave, 3 for one-third-octave).
edition	"2014" (IEC 61260-1:2014, classes 1/2) or "1995" (IEC 61260:1995 / ANSI S1.11-2004, classes 0/1/2).
sos	Per-band second-order sections of the analysed bank (one array per band), kept so the relative attenuation can be recomputed with scipy.signal.sosfreqz exactly as the verifier does.
band_frequencies	The exact mid-band frequencies f_m in Hz.
factors	Per-band decimation factor; the band’s processing sample rate is fs / factor (the multirate rate the SOS were designed at). Stored because the response must be evaluated at that decimated rate, which the verifier’s public return does not expose.
fs	The bank’s full sampling rate in Hz.
num_points	Frequency grid points per band used by the verification, retained so the redrawn curve matches the analysed grid.
range_limited	True when at least one band’s stop-band mask extends beyond its processing Nyquist frequency, so the verification could not exercise the full Table 1 mask there (the multirate anti-aliasing removes signal energy beyond it, but the limits are not demonstrated); the stated class then attests the verified frequency range and the .report() fiche prints a qualifying note.

FilterComplianceResult.available_classes()

FilterComplianceResult.available_classes() -> list[int]

The performance classes carried by the per-band verdict dictionaries.

Reads the margin_class<n>_db keys of a band verdict, so it reflects the edition (the 1995 edition adds class 0; the 2014 edition keeps only classes 1 and 2). An empty result (a bank with no bands in range) carries no verdicts, so this returns an empty list.

FilterComplianceResult.plot()

FilterComplianceResult.plot(
    ax: Axes | None = None,
    *,
    language: str = 'en',
    **kwargs: Any,
) -> Axes

Plot the worst-margin band against its class-limit corridor.

Draws the measured relative attenuation of the binding band over the acceptance corridor of the achieved (or, when non-compliant, the loosest) class; see phonometry._plot.metrology.plot_filter_class. Requires matplotlib (pip install phonometry[plot]) and returns the Axes.

Parameters

Name	Description
language	Label language, "en" (default) or "es".

FilterComplianceResult.reference_class()

FilterComplianceResult.reference_class() -> int

The class whose corridor the fiche/plot overlays.

The achieved overall class when the bank complies, else the loosest class of the edition (the one it comes closest to meeting).

Raises

Exception	When
ValueError	If the result carries no bands, so there is no reference class to report.

FilterComplianceResult.report()

FilterComplianceResult.report(
    path: str,
    *,
    metadata: ReportMetadata | None = None,
    engine: str = 'reportlab',
    verbose: bool = False,
    language: str = 'en',
) -> str

Render an IEC 61260-1 filter-class-compliance fiche to a PDF.

Writes a one-page accredited report: the standard-basis line, an optional metadata header block, a per-band classification table beside the mask-overlay plot (the result’s own plot), the boxed class-compliance result, an optional verdict row against a supplied required_class and a footer with the fixed disclaimer.

Parameters

Name	Description
path	Destination path of the PDF file.
metadata	Optional ReportMetadata; None produces a prediction fiche (body, result and disclaimer only). A supplied required_class drives the verdict row.
engine	Rendering back end; only "reportlab" is supported.
verbose	Accepted for a uniform signature; it has no effect on the single-layout filter-compliance fiche.
language	Fiche language: "en" (default, English) or "es" (Spanish, with a comma decimal separator).

Returns: The written path as a str.

Raises

Exception	When
ValueError	If engine is not "reportlab".
ImportError	If reportlab is not installed (pip install phonometry[report]).

verify_aircraft_noise_system

verify_aircraft_noise_system(
    *,
    directional: dict[float, dict[float, float]] | None = None,
    frequency_response: dict[float, float] | None = None,
    linearity: dict[str, float] | None = None,
    resolution: float | None = None,
) -> dict[str, Any]

Verify measured performance against IEC 61265:1995 tolerances.

Each supplied measurement is checked against the standard’s limit; the one-third-octave filtering itself is covered by the IEC 61260 class-2 verification (subclause 4.6) and is not repeated here.

Parameters

Name	Description
directional	Microphone directional response as {frequency_hz: {angle_deg: |Δsensitivity| dB}} (Table 1, §4.4.2).
frequency_response	System response deviations {frequency_hz: deviation_db} against the ±1.5 dB limit (§4.5.1).
linearity	Level non-linearity {"reference": dB, "other": dB} against the ±0.4/±0.5 dB limits (§4.5.2).
resolution	Readout resolution, in dB, against the 0.1 dB limit (§4.7).

Returns: {"passed": bool, "checks": [{"quantity", "limit", "value", "ok", ...}]}; passed is the conjunction of every check.

Raises

Exception	When
ValueError	If a frequency or angle is out of the tabulated range.

verify_filter_class

verify_filter_class(
    bank: OctaveFilterBank,
    num_points: int = 32768,
    *,
    edition: str = '2014',
) -> dict[str, Any]

Verify a filter bank against the IEC 61260 class limits.

Each band’s relative attenuation (referenced to the attenuation at its exact mid-band frequency) is checked against every acceptance-limit class of the selected edition’s Table 1, evaluated on a dense frequency grid up to the band’s processing Nyquist. The Table 1 breakpoint frequencies inside that range are always included in the evaluation, so the pass-band constraints are checked even if the grid were coarse. Frequencies beyond the processing Nyquist cannot carry signal energy at the band’s decimated rate (the multirate anti-aliasing filter removes them), so they are treated as compliant; because the Table 1 limits there are nevertheless not demonstrated, the returned range_limited flag is set whenever a band’s stop-band mask extends beyond its processing Nyquist, and the per-band checked_to_omega records how far the check reached.

Parameters

Name	Description
bank	The filter bank to verify (its designed SOS are analyzed; works for stateful and stateless banks alike).
num_points	Number of frequency grid points per band (>= 16).
edition	"2014" (IEC 61260-1:2014, classes 1/2) or "1995" (IEC 61260:1995 / ANSI S1.11-2004, adds the stricter class 0).

Returns: Dict with overall_class (the strictest class every band meets, or None), range_limited (True when at least one band’s stop-band mask extends beyond its processing Nyquist, so the returned class attests the verified frequency range rather than the full Table 1 mask; see above) and bands: a list of {"freq", "class", "checked_to_omega", "margin_class<c>_db"} for each class c of the edition, where a positive margin means the limits are met with that much room and checked_to_omega is the highest normalized frequency the band’s verification could reach (its processing Nyquist over f_m).

verify_weighting_class

verify_weighting_class(
    wf: WeightingFilter,
    *,
    sweep_points: int = 4096,
) -> dict[str, Any]

Verify a frequency-weighting filter against its standard’s tolerances.

A/C/Z are checked against IEC 61672-1:2013 Table 3 (classes 1 and 2). The historical B weighting is checked against ANSI S1.4-1983: Table IV design goals with the Table V tolerance limits, whose instrument Types 1 and 2 fill the class 1 / class 2 verdict slots (an overall_class of 1 then reads “ANSI S1.4-1983 Type 1”). AU is checked against IEC 61012:1990: design goals are nominal A + nominal U (Table 1, plus the subclause 2.2 explicit AU values at 25/31.5/40 kHz) with the single Table 1 tolerance set for the filter as a separate unit, so both class slots carry the same margin and overall_class is 1 (complies) or None. G is not supported here (ISO 7196 defines one +/-1 dB instrumentation tolerance, no class structure; the CI conformance report pins it), nor is D (the tolerance tables of the withdrawn IEC 537 did not survive it; the conformance report pins the D response against its published transfer function and tabulated curve).

The filter’s relative response (normalized to its 1 kHz gain) is evaluated at the exact base-10 frequency behind each nominal label below the Nyquist frequency (IEC 61672-1 Table 3 NOTE: the design goals are computed at f = 1000 * 10^(0.1 (n - 30)), e.g. 15 848.9 Hz for “16 kHz”; IEC 61672-3:2013 subclause 13.3 tests the deviation at the same exact frequencies, and IEC 61012 Table 1 lists the same exact frequencies). The deviation from the design-goal weighting is checked against the two acceptance masks.

A dense logarithmic sweep between the checked frequencies additionally enforces IEC 61672-1 subclause 5.5.7: at any frequency between two adjacent nominal frequencies, the deviation of the response from the analytic design goal (Annex E for A/C/Z, the ANSI S1.4-1983 Appendix C formulas for B, the A response cascaded with the IEC 61012 Table 2 poles for AU) must stay within the larger of the two adjacent limits. Without it a resonance or notch between the nominal frequencies would go unnoticed (for B and AU the sweep is applied as the analogous engineering check). Both the per-frequency verdicts and the sweep must pass for overall_class. The sweep samples sweep_points grid frequencies; a violation narrower than the grid spacing could in principle fall between samples, so raise sweep_points for higher-Q suspects (the verdict attests the sampled grid, not a continuous proof).

The response is taken from the designed second-order sections (evaluated with sosfreqz at their design rate), so it is exact and deterministic; it does not model the runtime resampling stages that high_accuracy adds around them, whose anti-alias response is flat across the audio band checked here. The Z weighting is a flat bypass and always complies.

When rows that carry a finite lower acceptance limit fall at or above the Nyquist frequency (e.g. the 8-16 kHz class 1 rows of a 16 kHz sampled system, or the 25-40 kHz AU rows of a 48 kHz one), they cannot be checked and range_limited is True: the returned class then attests conformance over the checked frequencies only, not conformance over the standard’s full frequency range.

Parameters

Name	Description
wf	The weighting filter to verify (A, B, C, AU or Z).
sweep_points	Number of points of the 5.5.7 between-nominals sweep (>= 64).

Returns: Dict with overall_class (1, 2 or None), range_limited (see above), bands: a list of {"freq", "class", "deviation_db", "margin_class1_db", "margin_class2_db"} where freq is the nominal label, a positive margin means the limits are met with that much room, and between_nominals: {"worst_freq", "margin_class1_db", "margin_class2_db"} for the sweep.

weighting_class_limits

weighting_class_limits(
    weighting_class: int,
) -> tuple[np.ndarray, np.ndarray, np.ndarray]

IEC 61672-1:2013 Table 3 acceptance limits for a performance class.

The limits apply to every IEC 61672-1 weighting (A, C, Z); they qualify the deviation of the measured relative response from the design goal at each nominal frequency, not the response itself. (The B and AU masks that verify_weighting_class uses come from ANSI S1.4-1983 Table V and IEC 61012:1990 Table 1 instead and are not returned here.)

Parameters

Name	Description
weighting_class	1 or 2 (IEC 61672-1:2013 performance class).

Returns: Tuple (frequencies, lower, upper) of the 34 nominal frequencies (Hz) and the lower/upper deviation limits in dB. A lower limit of -inf means only the upper limit applies.