1、BRITISH STANDARD BS6397:1983 IEC263:1982 Specification for Scales and sizes for plotting frequency characteristics and polar diagrams UDC 621.3.085.4:621.3.018.4:621.3.012.12BS6397:1983 This British Standard, having been prepared under the directionof the Electronic Equipment Standards Committee,was
2、 published underthe authority of the BoardofBSI and comes intoeffecton 29July1983 BSI 12-1999 The following BSI references relate to the work on this standard: Committee reference EEL/24 Draft for comment 82/32494 DC ISBN 0 580 13381 8 Committees responsible for this British Standard This British St
3、andard was published under the direction of the Electronic Equipment Standards Committee EEL/-. Its preparation was entrusted to Technical Committee EEL/24 upon which the following bodies were represented: British Radio and Electronic Equipment Manufacturers Association Department of Health and Soci
4、al Security Department of Industry(National Physical Laboratory) Institution of Electronic and Radio Engineers Post Office Royal National Institute for the Deaf Society of Hearing Aid Audiologists Limited Amendments issued since publication Amd. No. Date of issue CommentsBS6397:1983 BSI 12-1999 i Co
5、ntents Page Committees responsible Inside front cover National foreword ii Introduction 1 1 Scope 1 2 Logarithmic frequency scales 1 3 Polar level diagrams 1 Appendix A Examples of the requirements specified in this standard 2 Figure A.1 Example of ventilating noise spectrum with a scale proportions
6、uchthat the length of the abscissa corresponding to a frequencyratio of10:1isequal to the length of the ordinate correspondingto25dB 3 Figure A.2 Example of a microphone calibration curve showing sensitivitylevelS as a function of frequency f, with a scale proportion of10dBfor a frequency ratio10:1
7、4 Figure A.3 Example of loudspeaker response with a scale proportion of50dBfor a frequency ratio10:1 4 Figure A.4 Example of a polar diagram with a reference circle radius corresponding to50dB showing sound level at a distance of150m from anaircraft 5 Figure A.5 Example of a polar diagram with a ref
8、erence circle radius corresponding to25dB showing the directional response of a radial horn loudspeaker at8000Hz 6BS6397:1983 ii BSI 12-1999 National foreword This British Standard has been prepared under the direction of the Electronic Equipment Standards Committee. It is identical with IEC Publica
9、tion263:1982 “Scales and sizes for plotting frequency characteristics and polar diagrams” published by the International Electrotechnical Commission (IEC). Terminology and conventions. The text of the International Standard has been approved as suitable for publication as a British Standard without
10、deviation. Some terminology and certain conventions are not identical with those used in British Standards. Attention is drawn especially to the following. In Figure A.3 the comma has been used as a decimal marker. In BritishStandards it is current practice to use a full point on the baseline as the
11、decimal marker. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This doc
12、ument comprises a front cover, an inside front cover, pagesi andii, pages1 to6 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS6397:1983 BSI 12-1999 1 Introductio
13、n In order that a proper impression may be gained from a graph in which a response is plotted as a level(in decibels) against frequency on a logarithmic scale, it is important that the proportions of the scales be standardized. Otherwise, a spectrum or response curve can be made to appear unduly fla
14、t or unduly steep by compression or expansion of one of the scales. The ultimate interest is usually an output spectrum that results from the combination of an input spectrum with several individual response characteristics such as those of a microphone, amplifier, loudspeaker and perhaps a transmis
15、sion loss. Such characteristics may similarly be combined for instruments such as hearing aids, recorders and vibration measuring apparatus. The contribution of each element to the final result is more readily understood if each characteristic is plotted to scales having a standard proportion. For d
16、isplaying response-frequency characteristics, different ranges and orders of accuracy are needed. Thus, a range of10dB may suffice for the response of a standard microphone, but a range of more than60dB may be required for a filter. Although these requirements emphasize the need for different scale
17、proportions, the number of proportions should be kept at a minimum to facilitate comparisons. If identical scale sizes are used, curves on translucent paper may be laid over one another for easy comparison. Although graphs for publication may be reduced to fit the printed page, the use of a standard
18、 proportion makes it feasible to compare graphs from different publications by direct superposition of suitable enlargements. 1 Scope 1.1 This standard specifies standard proportions for the scales for plotting frequency characteristics and polar diagrams. 1.2 This standard does not apply to audiogr
19、ams. 2 Logarithmic frequency scales For graphs in which a level(in decibels) is plotted against frequency on a logarithmic scale, the scale proportions shall be those for which the length for a10:1frequency ratio is equal to the length for a level difference of10dB,25dB or50dB on the ordinate scale.
20、 3 Polar level diagrams 3.1 For polar plots in which a level, in decibels, is shown increasing outward along a radius on a linear scale, the maximum level should preferably be plotted on, or within5dB of, a reference circle whose radius corresponds to a difference in level of50dB. Alternatively, the
21、 maximum level should preferably be plotted on, or within2.5dB of, the reference circle whose radius corresponds to a difference in level of25dB. The tolerance limits on the radius of the reference circle correspond respectively to 0.5dB and 0.25dB. These requirements apply for whatever length is ch
22、osen to represent1dB. 3.2 For an absolute level, referred to a fixed reference quantity, when the radius of the reference circle corresponds to a difference in level of50dB, the level assigned to the reference circle shall be a multiple of10dB. When the radius corresponds to a difference in level of
23、25dB, the level assigned to the reference circle shall be a multiple of5dB. The level represented by the reference circle should be within5dB(or2.5dB) of the maximum level to be plotted. 3.3 For a relative level, such as the difference between an absolute level at a stated distance from a transducer
24、 in a particular direction, and the absolute level at the stated distance in a reference direction, the relative level assigned to the reference circle shall be0dB and the angle assigned to the reference direction shall be0 .BS6397:1983 2 BSI 12-1999 Appendix A Examples of the requirements specified
25、 in this standard Examples of original plots with the three scale proportions specified in this standard are shown respectively in Figure A.1 (page3), Figure A.2 and Figure A.3 (page4). The examples are drawn with real data, but are not intended to restrict the plotting of a characteristic to any pa
26、rticular one ofthe scale proportions illustrated. One dB is represented respectively by the convenient sizes of1mm,2mm and5mm, corresponding to50dB,25dB and10dB equal in length to the specified size of50mm for the10:1 frequency ratio on the logarithmic scale. It should be noted that the vertical rul
27、ings on Figure A.1 and Figure A.3 are equally spaced, with5mm representing one-third octave, thus allowing the use of linear graph paper. Figure A.4 (page5), is an example of a polar diagram according to this standard, showing the sound level at a distance of150m from an aircraft on the ground. One
28、decibel is represented by2mm, and the radius of the reference circle is defined by a level difference of50dB; hence the radius of the reference circle is100mm. The maximum sound level to be plotted is118dB, and the multiple of10dB within5dB of this maximum level is120dB. Thus the sound level represe
29、nted by the reference circle is120dB. Figure A.5 (page6), is an example of a polar diagram according to this standard, showing the directional response of a radial horn loudspeaker at8000Hz, relative to the response on the axis at the given distance from the loudspeaker. One decibel is represented b
30、y4mm, and the radius of the reference circle is defined by a level difference of25dB; hence the radius of the reference circle is100mm. As usual, the reference circle represents0dB relative level. The200mm diameter of the reference circle is such that a fully circular directivity pattern is just sma
31、ll enough to be reproduced on paper ofA4 size. Any additional plotting space outside the reference circle, such as at the top and bottom of these examples, is available for levels that exceed somewhat the level represented by the reference circle.BS6397:1983 BSI 12-1999 3 Figure A.1 Example of venti
32、lating noise spectrum with a scale proportionsuchthat the length of the abscissa corresponding to a frequencyratio of10:1isequal to the lengthoftheordinate correspondingto25dBBS6397:1983 4 BSI 12-1999 Figure A.2 Example of a microphone calibration curve showing sensitivitylevelS as a function of fre
33、quency f, with a scale proportion of10dBfor a frequency ratio10:1 Figure A.3 Example of loudspeaker response with a scale proportion of50dBfor a frequencyratio10:1BS6397:1983 BSI 12-1999 5 Figure A.4 Example of a polar diagram with a reference circle radius corresponding to50dBshowing sound level at
34、 a distance of150m from anaircraftBS6397:1983 6 BSI 12-1999 Figure A.5 Example of a polar diagram with a reference circle radius corresponding to25dBshowing the directional response of a radial horn loudspeaker at8000HzblankBS6397:1983 IEC263:1982 BSI 389 Chiswick High Road London W4 4AL BSIBritishS
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