What is BS EN 61260-1- Octave-band and fractional-octave-band filters about?
BS EN 61260-1 is the first part of an international multi-series standard that discusses the use of electroacoustics for various purposes.
BS EN 61260-1 specifies performance requirements for analogue, sampled data, and digital implementations of band-pass filters. The extent of the pass-band region of a filter's relative attenuation characteristic is a constant percentage of the exact mid-band frequency for all filters of a given bandwidth.
An instrument conforming to the requirements of BS EN 61260-1 may contain any number of contiguous band-pass filters covering any desired frequency range.
Performance requirements are provided for two filter classes:
- Class 1
- Class 2
In general, specifications for class 1 and class 2 filters have the same design goals and differ in the acceptance limits and the range of operational temperature. Acceptance limits for class 2 are greater than or equal to, those for class 1. Maximum-permitted expanded uncertainties of measurement are also specified in BS EN 61260-1. Performance requirements are also given in BS EN 61260-1 gives performance requirements for designs where the octave frequency ratio and the mid-band frequencies are powers of ten.
BS EN 61260-1 specifies the ranges of environmental conditions for the operation of the filters. The required range depends on whether the instrument containing the filters is designed to be operated in a controlled environment or more generally in the field.
Band-pass filters conforming to the requirements of BS EN 61260-1 can provide frequency-band-filtered spectral information for a wide variety of signals, for example, time-varying, intermittent or steady; broadband or discrete frequency; and long or short durations.
Note: Band-pass filters conforming to the performance requirements of BS EN 61260-1 may be part of various measurement systems or may be an integral component of a specific instrument such as a spectrum analyzer.
Who is BS EN 61260-1- Octave-band and fractional-octave-band filters for?
BS EN 61260-1 on octave-band and fractional-octave-band filters is relevant to:
- Acousticians
- Manufacturers of microphones
- Manufacturers of the coupler
- Audiologists
- Manufacturers of the octave-band analyzer
- Manufacturers of testing apparatus
Why should you use BS EN 61260-1- Octave-band and fractional-octave-band filters?
Fractional-octave-band filter is a band-pass filter for which the ratio of upper band-edge frequency to lower band-edge frequency is the octave frequency ratio raised to an exponent equal to the applicable bandwidth designator.
BS EN 61260-1 uses an amended criterion for assessing conformance to a specification.
Conformance is demonstrated when:
- Measured deviations from design goals do not exceed the applicable acceptance limits
- The uncertainty of measurement does not exceed the corresponding maximum-permitted uncertainty
BS EN 61260-1 helps in determining the actual and maximum-permitted uncertainties of measuring a coverage probability of 95 percent. Unless more-specific information is available, the evaluation of the contribution of a specific filter or filter set to a total measurement uncertainty can be based on the acceptance limits and maximum-permitted uncertainties specified in BS EN 61260-1.
BS EN 61260-1 provides exact and nominal mid-band frequencies for octave-band and one-third octave-band filters for the usual range of audio frequencies. BS EN 61260-1 specifies a procedure for determining the nominal mid-band frequencies for fractional-octave-band filters with other bandwidth designators.
Overall, BS EN 61260-1 is useful as it describes the conformance to a specification that is established when measured deviations from design goals do not exceed the corresponding acceptance limits and the uncertainty of measurement does not exceed the corresponding maximum-permitted uncertainty of measurement for a coverage probability of 95%.
What’s changed since the last update?
BS EN 61260-1:2014 supersedes BS EN 61260:1996, which is withdrawn. BS EN 61260-1:2014 includes the following significant technical changes:
- The single document in the first edition of EN 61260:1995 is in EN 61260 series separated into three parts covering: specifications, pattern evaluation tests and periodic tests
- The EN 61260:1995 specified three performance categories: classes 0, 1 and 2. The EN 61260 series specifies requirements for class 1 and 2
- In the EN 61260:1995, the design goals for the specification can be based on base-2 or base 10 design. In EN 61260 series only base-10 is specified
- The reference environmental conditions have been changed from 20 °C / 65 % RH to 23 °C / 50 % RH
- EN 61260:1995 specified tolerance limits without considering the uncertainty of measurement for verification of the specifications. EN 61260 series specifies acceptance limits for the observed values and maximum-permitted uncertainty of measurements for laboratories testing conformance to specifications in the standard
