filters.periodic_tests

Periodic tests of band filters (IEC 61260-3:2016): test frequencies and verdict.

IEC 61260-3:2016 is the short list of tests a laboratory runs on a working octave-band or fractional-octave-band filter every year or two, to show that it still meets the class it was built to under IEC 61260-1:2014. This module gives two things for it.

The test frequencies of Clause 13. The relative attenuation of three filters of the set is measured at 15 normalized frequencies, an abbreviation of the Table 1 mask of IEC 61260-1 (13.3, NOTE 1). Formula (1) carries the octave-band frequency parameters $R_k$ of its Table 1 ($G^0$, $G^{1/8}$, $G^{1/4}$, $G^{3/8}$, $G$, $G^2$, $G^3$, $G^4$) to a bandwidth designator $1/b$,

and Formula (2) mirrors them below the mid-band, ${\Omega }_{-k}=1/{\Omega }_k$, with the same acceptance limits. For octave bands ${\Omega }_k=R_k$ (NOTE 2). periodic_test_frequencies returns the 15, for any $b$; Annex C prints them for one-third-octave filters to five decimals, and they are reproduced there to the last digit. It is the same mapping as Formula (9) of IEC 61260-1 that phonometry.filters.class_limits uses for its breakpoints.

The verdict on a laboratory’s results. verify_filter_periodic grades what a laboratory measured, clause by clause, by the conformance rule of IEC TC 29 that IEC 61260-3 5.1 states (phonometry.metrology.verify_conformance): the measured deviation within the acceptance limit and the actual expanded uncertainty within the maximum permitted by Annex B of IEC 61260-1:2014, both inclusive. The clauses it grades are the ones that are a measured deviation with such a pair:

• 10.2, the relative attenuation at the exact mid-band frequency of every filter of the set: $\pm 0.4$ dB (class 1) or $\pm 0.6$ dB (class 2), with the Annex B maximum Table B.1 sets for the relative attenuation measured, 0.20 dB up to 2 dB and 0.30 dB above (a filter that has drifted past 2 dB at its mid-band is a failure, not a result 5.3 makes unusable);
• 10.3, the alternative for time-invariant filters: the deviation of the time-averaged output of an exponential sweep from Formula (17) of IEC 61260-1, within the same limits (10.3.6), with the Annex B maximum for time-invariant operation, 0.20 dB (9.2.3);
• 11.7, the level linearity deviation of three filters over the linear operating range: the limits of IEC 61260-1 5.13.3 ($\pm 0.5$ dB or $\pm 0.6$ dB) down to 40 dB below the upper boundary and of 5.13.4 ($\pm 0.7$ dB or $\pm 0.9$ dB) further down, with the Annex B maxima 0.20 dB and 0.35 dB on either side of those 40 dB;
• 11.9, the level linearity on every other level range, 30 dB below its upper boundary: 5.13.3, 0.20 dB;
• 13, the relative attenuation of the same three filters at the 15 test frequencies against Table 1 of IEC 61260-3, with the Annex B maxima 0.20 dB, 0.30 dB and 0.50 dB for a relative attenuation up to 2 dB, up to 40 dB and above 40 dB.

A stop-band row of Table 1 prints a minimum and $+\infty$ (“+70; +∞”), an acceptance interval with no upper limit, which is how it is judged.

What a complete test covers. 11.3 and 13.1 test the level linearity and the relative attenuation of three filters of the set, and 13.4 tests each of them at every $k$ from -7 to 7 whose frequency lies above 0.5 times the exact mid-band frequency of the lowest filter of the set and below 1.5 times that of the highest. A record with fewer filters, or with a NaN at a frequency 13.4 requires, is incomplete (FilterPeriodicVerification.incomplete) and does not pass. The record says which filter a level linearity result was measured on (linearity_midband_frequencies_hz) and where the set and the tested filters lie (set_midband_frequencies_hz, tested_midband_frequencies_hz); without them that coverage cannot be checked, FilterPeriodicVerification.coverage_checked is false and the statement says so.

What 5.3 makes unusable. A result whose actual uncertainty exceeds the maximum permitted “shall not be used to evaluate conformance to this standard for periodic testing” (5.3). Such a result is neither a pass nor, by itself, a failure of the filter; FilterPeriodicVerification.unusable lists them and the verdict does not pass while any is left.

What a pass here is, and is not. It is a verdict on the numbers put in. The checks that are not a deviation with a maximum-permitted uncertainty are the laboratory’s own record: the instruction manual and markings of Clause 4, the preliminary inspection of Clause 6, the power supply of Clause 7, the environmental conditions of Clause 8, the overload indications of 11.5 and 11.8, and the self-generated noise of Clause 12, which compares the output with the input short-circuited against the lower limit the manual states and has no maximum-permitted uncertainty in Annex B. And even a filter that passes every periodic test supports no general conclusion about the specifications of IEC 61260-1 unless the model’s pattern approval under IEC 61260-2 is publicly available (1.5): the statement the verdict writes is the one Clause 14 k) or l) prescribes for the case at hand.

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

FilterPeriodicMeasurements(
    midband_attenuations_db: Sequence[float] | None = None,
    midband_uncertainties_db: Sequence[float] | None = None,
    bandwidth_deviations_db: Sequence[float] | None = None,
    bandwidth_uncertainties_db: Sequence[float] | None = None,
    set_midband_frequencies_hz: Sequence[float] | None = None,
    linearity_deviations_db: Sequence[float] | None = None,
    linearity_levels_below_upper_db: Sequence[float] | None = None,
    linearity_uncertainties_db: Sequence[float] | None = None,
    linearity_midband_frequencies_hz: Sequence[float] | None = None,
    range_linearity_deviations_db: Sequence[float] | None = None,
    range_linearity_uncertainties_db: Sequence[float] | None = None,
    relative_attenuations_db: Sequence[Sequence[float]] | None = None,
    relative_attenuation_uncertainties_db: Sequence[Sequence[float]] | None = None,
    tested_midband_frequencies_hz: Sequence[float] | None = None,
)

What a laboratory measured in the periodic tests of IEC 61260-3:2016.

Every result comes with the actual expanded uncertainty the laboratory calculated for it, for a coverage probability of 95 % (5.2), in the same position of a sequence of the same length. A clause left at None was not measured. Everything is in decibels.

Attributes

FilterPeriodicVerification(
    filter_class: int,
    fraction: float,
    pattern_approval_public: bool,
    measurements: FilterPeriodicMeasurements,
    clauses: tuple[PeriodicTestClause, ...],
)

The IEC 61260-3:2016 verdict on the periodic tests of a band filter.

Attributes

FilterPeriodicVerification.clause(clause: str) -> PeriodicTestClause

The verdict on one clause.

Parameters

Returns: Its PeriodicTestClause.

Raises

property

Whether the record says enough to check what a complete test covers.

The filter of every 11.7 result (linearity_midband_frequencies_hz) and, for Clause 13, the mid-band frequencies of the set and of the tested filters, without which incomplete cannot count the three filters of 11.3 or the test frequencies of 13.4.

property

(clause, result) for every result outside its acceptance limits.

property

(clause, what is short) for every result a complete clause lacks.

11.3 and 13.1: the level linearity and the relative attenuation of three filters; 13.4: each tested filter at every test frequency above 0.5 times the exact mid-band frequency of the lowest filter of the set and below 1.5 times that of the highest. A clause not measured at all is in missing instead. What the record does not say cannot be listed here, and coverage_checked tells whether it said enough.

property

The clauses a complete periodic test grades that were not measured.

"10" (10.2 or 10.3), "11.7" and "13"; 11.9 applies only to a filter with more than one level range and is never missing.

property

Whether the filter completed the periodic tests successfully.

Every clause a complete test grades was measured on the filters and at the frequencies it requires (nothing missing or incomplete), and every result demonstrates conformance: no deviation outside its limits and no uncertainty above its maximum.

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

Draw every result’s margin to its acceptance limits, clause by clause.

One marker per result, grouped by clause: the distance from the deviation to its nearer acceptance limit, with the actual uncertainty as its error bar; a result at or above zero lies within its limits. A result drawn hollow is one 5.3 forbids using.

Requires matplotlib (pip install phonometry[plot]); returns the Axes.

Parameters

property

The statement IEC 61260-3:2016 Clause 14 prescribes for the result.

14 m) when a result exceeds its acceptance limits, followed by the tests that did not complete and why; the 5.3 notice when results cannot be used; a notice naming the clauses not measured and the filters and frequencies a clause lacks; and otherwise 14 k) with a public pattern approval or 14 l) without one, which carries the caveat of 1.5: without it no general conclusion about IEC 61260-1 can be drawn. A pass on a record that does not say which filters and frequencies it covers ends by saying that this was not checked.

property

(clause, result) for every result 5.3 forbids using.

Constant (mapping).

PERIODIC_TEST_ATTENUATION_LIMITS_DB = {1: ((-0.4, 0.4), (-0.4, 0.5), (-0.4, 0.7), (-0.4, 1.4), (16.6, inf), (40.5, inf), (60.0, inf), (70.0, inf)), 2: ((-0.6, 0.6), (-0.6, 0.7), (-0.6, 0.9), (-0.6, 1.7), (15.6, inf), (39.5, inf), (54.0, inf), (60.0, inf))}

periodic_test_frequencies(fraction: float) -> np.ndarray

The 15 normalized test frequencies of IEC 61260-3:2016 Clause 13.

${\Omega }_k$ for k = -7, -6, ..., 7, by Formula (1) for $k\ge 0$ and Formula (2), ${\Omega }_{-k}=1/{\Omega }_k$, below the mid-band. Multiply by a filter’s exact mid-band frequency for the test frequencies in hertz (C.2). 13.4 drops the ones below 0.5 times the lowest mid-band frequency of the set or above 1.5 times the highest.

Parameters

Returns: A read-only array of the 15 normalized frequencies, ascending, index k + 7; PERIODIC_TEST_ATTENUATION_LIMITS_DB[c][abs(k)] are their acceptance limits.

Raises

PeriodicTestClause(
    clause: str,
    title: str,
    labels: tuple[str, ...],
    verifications: tuple[ConformanceVerification, ...],
    normalized_frequencies: tuple[float, ...] | None = None,
)

The verdict on one clause of IEC 61260-3:2016.

Attributes

property

The results whose deviation exceeds its acceptance limits.

Only those measured with an acceptable uncertainty: a result that is also unusable shows nothing about the filter (5.3).

property

Whether every result of the clause demonstrates conformance (5.1).

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

Draw every result of the clause against its limits.

Clauses 10 and 11 are drawn as IEC 61260-1:2014 Figure C.1 draws its examples: the limits, the deviation, its uncertainty and the maximum-permitted band. Clause 13, whose limits run from a few tenths of a decibel to 70 dB, is drawn as each result’s margin to its nearer limit against the test frequency: at or above zero it conforms.

Requires matplotlib (pip install phonometry[plot]); returns the Axes.

Parameters

property

The results whose uncertainty exceeds the maximum permitted (5.3).

verify_filter_periodic(
    filter_class: int,
    measurements: FilterPeriodicMeasurements,
    *,
    fraction: float,
    pattern_approval_public: bool = False,
) -> FilterPeriodicVerification

Grade the periodic tests of a band filter, IEC 61260-3:2016.

Each clause measured is judged result by result by the conformance rule of IEC TC 29 (5.1), with the acceptance limits the clause sets and the maximum-permitted uncertainties of IEC 61260-1:2014 Annex B; see the module docstring for which clause reads which. The verdict passes when every clause a complete test grades was measured (10.2 or 10.3, 11.7 and 13) on the three filters and at the test frequencies it requires, and every result conforms; its statement is the text Clause 14 prescribes for the case.

Parameters

Returns: A FilterPeriodicVerification.

Raises