GB/T 3241.2-2025Electroacoustics - Octave-band and fractional-octave-band filters - Part 2: Pattern evaluation tests (English PDF)

Foreword

This document is in accordance with the provisions of GB/T 1.1-2020 "Guidelines for standardization work Part 1: Structure and drafting rules for standardization documents" Drafting.

This document is part 2 of GB/T 3241 "Electroacoustic octave and fractional octave filters". GB/T 3241 has been published the following parts.

--- Part 1: Specification;

--- Part 2: Type evaluation test.

This document partially replaces the type evaluation test in GB/T 3241-2010 "Electroacoustic Octave and Fractional Octave Filters" Compared with the relevant content of GB/T 3241-2010, in addition to structural adjustments and editorial changes, the main technical changes are as follows.

a) Added test submission requirements (see Chapter 4);

b) Added essential functions and general requirements (see 6.1);

c) The requirements for test instruments have been changed (see 6.2, 5.2 of the 2010 edition);

d) Added performance test items such as overload indicator and power supply (see 7.3 and 7.5);

e) Deleted performance test items such as anti-aliasing filter and flat frequency response (see 5.7 and 5.9 of the 2010 edition);

f) The performance test method has been changed (see Chapter 7, Chapter 5 of the 2010 edition);

g) The test methods for electromagnetic compatibility items have been changed (see Chapter 8, Chapter 8 of the 2010 edition);

h) The test method for the influence of ambient air temperature and relative humidity has been changed (see Chapter 9, 5.10 of the 2010 edition);

i) Added requirements for type evaluation reports (see Chapter 10).

This document is equivalent to IEC 61260-2:2016 "Electroacoustic octave and fractional octave filters Part 2: Type evaluation test".

The following minimal editorial changes were made to this document.

--- Incorporated the revised content of IEC 61260-2:2016/Amd1.2017, the outer margin position of the clauses involved is marked with vertical Straight double lines (||) are marked.

Introduction

A filter is a device that separates the components of a signal by frequency, and octave and fractional octave filters are devices that have a single A bandpass filter with a transmission band and an upper cutoff frequency and a lower cutoff frequency ratio equal to an octave frequency ratio or a certain power thereof. Octave and fractional Octave filters are usually used in conjunction with sound measuring instruments such as sound level meters for spectral analysis of sound signals.

GB/T 3241 aims to specify the performance requirements for octave and fractional octave filters and to describe the type evaluation tests and periodic tests.

The method is planned to consist of three parts.

--- Part 1: Specification. The purpose is to specify the performance requirements for octave and fractional octave filters.

--- Part 2: Type evaluation test. The purpose is to ensure that all testing laboratories use a consistent method to perform octave and fractional Type evaluation test of octave band filters.

--- Part 3: Periodic test. The purpose is to ensure that all testing laboratories or metrology laboratories perform octave testing in a consistent manner.

and periodic experiments with fractional-octave filters.

To evaluate compliance with performance requirements, this document uses different criteria from GB/T 3241-2010.

GB/T 3241-2010 does not provide any requirements or recommendations for taking measurement uncertainty into account in the evaluation of conformity to performance requirements.

Due to the lack of requirements or recommendations on measurement uncertainty, when the measured deviation from the design target is close to the limit of the allowable deviation, the determination of compliance with the requirement becomes ambiguous. If compliance is determined based on whether the measured deviation exceeds the limit, then the octave and the end user of the fractional-octave band filter will be subject to the risk that the actual deviation from the design target exceeds the limit.

To eliminate ambiguity, the 29th Technical Committee of the International Electrotechnical Commission (IEC) determined at its 1996 meeting that in formulating standards, the measurement uncertainty should be taken into account when formulating the performance evaluation rules.

This document adopts the modified criteria for compliance with the requirements. Compliance is confirmed when the following conditions are met simultaneously.

a) the measured deviation from the design target does not exceed the applicable acceptance limit;

b) The measurement uncertainty does not exceed the corresponding maximum permissible uncertainty.

The acceptance limits are similar to the design and manufacturing tolerance limits in GB/T 3241-2010.

The actual measurement uncertainty and the maximum allowable measurement uncertainty are determined based on a coverage probability of 95%, unless there is more specific information.

Otherwise, the acceptance limits and maximum allowable uncertainties specified in this document can be used to evaluate specific octave or fractional octave filters.

or the contribution of the filter bank to the total measurement uncertainty.

Electroacoustic Octave and Fractional Octave Filters Part 2: Type evaluation tests

1 Scope

1.1 This document provides verification that octave and fractional octave filters (hereinafter referred to as filters) conform to GB/T 3241.1-2025.

Details of all required tests for the mandatory specifications.

1.2 These tests and test methods apply to both Class 1 and Class 2 filters. The purpose is to ensure that all testing laboratories use consistent methods.

The type evaluation test shall not be carried out in accordance with the law.

2 Normative references

The contents of the following documents constitute essential clauses of this document through normative references in this document.

For referenced documents without a date, only the version corresponding to that date applies to this document; for referenced documents without a date, the latest version (including all amendments) applies to this document.

GB/T 3241.1-2025 Electroacoustic octave and fractional octave filters Part 1: Specification (IEC 61260-1.

2014, IDT)

GB/T 9254.1-2021 Electromagnetic compatibility of information technology equipment, multimedia equipment and receivers Part 1: Emission requirements (CISPR32.2015,MOD) Note. There is no technical difference between the content cited in GB/T 9254.1-2021 and the content cited in CISPR22.2008.

GB/T 17626.2-2018 Electromagnetic compatibility test and measurement technology Electrostatic discharge immunity test (IEC 61000-4-2.

2008, IDT)

GB/T 17626.3-2023 Electromagnetic compatibility test and measurement technology Part 3: Radio frequency electromagnetic field radiation immunity test (IEC 61000-4-3:2020,IDT) Note. There is no technical difference between the referenced content of GB/T 17626.3-2023 and the referenced content of IEC 61000-4-3:2006.

GB/T 17626.6-2017 Electromagnetic compatibility test and measurement technology Radio frequency field induced conducted disturbance immunity (IEC 61000-4-6:2013,IDT) GB/T 17626.20-2014 Electromagnetic compatibility test and measurement technology Transverse electromagnetic wave (TEM) emission and immunity test in waveguide Test (IEC 61000-4-20:2010, IDT) GB/T 17799.2-2023 General electromagnetic compatibility standards Part 2: Immunity standards for industrial environments (IEC 61000-6-2:2016,MOD) Note. There is no technical difference between the referenced content of GB/T 17799.2-2023 and the referenced content of IEC 61000-6-2:2005.

ISO/IEC Guide 98-3 Measurement uncertainty Part 3: Guide to the expression of uncertainty in measurement (GUM..1995)

1995)]

Note. GB/T 27418-2017 Evaluation and expression of measurement uncertainty (ISO/IEC Guide 98-3..2008, MOD) ISO/IEC Guide 98-4 Measurement uncertainty Part 4: The role of measurement uncertainty in conformity assessment Note. GB/T 27430-2022 The role of measurement uncertainty in conformity assessment (ISO/IEC Guide 98-4..2012, MOD) ISO/IEC Guide 99 International Vocabulary of Metrology Basic Common Concepts and Related Terms (VIM) [Internationalvo-