SIST EN 61260:1998
(Main)Electroacoustics - Octave-band and fractional-octave-band filters
Electroacoustics - Octave-band and fractional-octave-band filters
Provides performance requirements and methods for testing the performance of analogue, sampled-data, and digital implementations of bandpass filters that comprise a filter set or spectrum analyzer.
Elektroakustik - Bandfilter für Oktaven und Bruchteile von Oktaven
Electroacoustique - Filtres de bande d'octave et de bande d'une fraction d'octave
Fournit les prescriptions concernant les performances et les méthodes d'essai des filtres passe-bandes de conceptions analogiques, à données échantillonnées et numériques, y compris un ensemble de filtres ou un analyseur de spectre.
Elektroakustika - Oktavni, poloktavni in terčni filtri (IEC 61260:1995)
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN 61260:1998
01-avgust-1998
(OHNWURDNXVWLND2NWDYQLSRORNWDYQLLQWHUþQLILOWUL ,(&
Electroacoustics - Octave-band and fractional-octave-band filters
Elektroakustik - Bandfilter für Oktaven und Bruchteile von Oktaven
Electroacoustique - Filtres de bande d'octave et de bande d'une fraction d'octave
Ta slovenski standard je istoveten z: EN 61260:1995
ICS:
17.140.50 Elektroakustika Electroacoustics
SIST EN 61260:1998 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN 61260:1998
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SIST EN 61260:1998
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SIST EN 61260:1998
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SIST EN 61260:1998
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SIST EN 61260:1998
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SIST EN 61260:1998
CEI
NORME
IEC
INTERNATIONALE
1260
INTERNATIONAL
Première édition
STANDARD First edition
1995-07
Electroacoustique -
Filtres de bande d'octave et de bande
d'une fraction d'octave
Electroacoustics -
Octave-band and fractional-octave-band filters
Copy"right — all rights reserved
Droits de reproduction réservés —
© CEI 1995
of this publication may be reproduced or utilized in
Aucune partie de cette publication ne peut être reproduite ni No part
any form or by any means, electronic or mechanical,
utilisée sous quelque forme que ce soit et par aucun pro-
including photocopying and microfilm, without permission
cédé, électronique ou mécanique, y compris la photocopie et
in writing from the publisher.
les microfilms, sans l'accord écrit de l'éditeur.
Genève, Suisse
Bureau Central de la Commission Electrotechnique Internationale 3, rue de Varembé
CODE PRIX
Commission Electrotechnique Internationale
International Electrotechnical Commission PRICE CODE U
MeeayHapoAHan 3neKrporeXHH4eCitaR HOMHCcuR
I EC-
vigueur
Pour prix, voir catalogue en •
For price, see current catalogue
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SIST EN 61260:1998
1260 ©IEC:1995 - 3 -
CONTENTS
Page
FOREWORD 5
Clause
1 Scope 7
2 Normative references 7
3 Definitions 9
17 4 Performance requirements
29 5 Test methods
41
Instrument marking 6
41
7 Instruction manual
Tables
21
1 Limits on relative attenuation for octave-band filters
A.1 Midband frequencies for octave-band and one-third-octave-band filters in
47
the audio range
51
B.1 Limits on relative attenuation for one-third-octave-band filters
Figure 1 - Illustration of minimum and maximum limits on relative attenuation for
23
class 1 octave-band filters
Annexes
45
A Midband frequencies
B Normalized frequencies at breakpoints of limits on minimum and maximum
49
relative attenuation for one-third-octave-band filters
ormance characteristics
C Recommendations for verification of the electrical pe rf
53
of bandpass filters
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SIST EN 61260:1998
1260 ©IEC:1995 - 5 -
INTERNATIONAL ELECTROTECHNICAL COMMISSION
ELECTROACOUSTICS -
OCTAVE-BAND AND FRACTIONAL-OCTAVE-BAND FILTERS
FOREWORD
The IEC (International Electrotechnical Commission) is a worldwide organization for standardization
1)
comprising all national electrotechnical committees (IEC National Committees). The object of the IEC is to
promote international cooperation on all questions concerning standardization in the electrical and
electronic fields. To this end and in addition to other activities, the IEC publishes International Standards.
Their preparation is entrusted to technical committees; any IEC National Committee interested in
the subject dealt with may participate in this preparatory work. International, governmental and
non-governmental organizations liaising with the IEC also participate in this preparation. The IEC
collaborates closely with the International Organization for Standardization (ISO) in accordance with
conditions determined by agreement between the two organizations.
The formal decisions or agreements of the IEC on technical matters, prepared by technical committees on
2)
which all the National Committees having a special interest therein are represented, express, as nearly as
possible, an international consensus of opinion on the subjects dealt with.
They have the form of recommendations for international use published in the form of standards, technical
3)
reports or guides and they are accepted by the National Committees in that sense.
In order to promote international unification, IEC National Committees undertake to apply IEC International
4)
Standards transparently to the maximum extent possible in their national and regional standards. Any
divergence between the IEC Standard and the corresponding national or regional standard shall be clearly
indicated in the latter.
The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
5)
equipment declared to be in conformity with one of its standards.
International Standard IEC 1260 has been prepared by IEC technical committee 29:
Electroacoustics.
This standard supersedes IEC 225 published in 1966.
The text of this standard is based on the following documents:
DIS Report on voting
29/292/DIS 29!304/RVD
rt
Full information on the voting for the approval of this standard can be found in the repo
on voting indicated in the above table.
Annexes A, B and C are for information only.
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SIST EN 61260:1998
1260 © IEC:1995 - 7 -
ELECTROACOUSTICS -
OCTAVE-BAND AND FRACTIONAL-OCTAVE-BAND FILTERS
1 Scope
1.1 This International Standard provides performance requirements and methods for
rf
testing the pe ormance of analogue, sampled-data, and digital implementations of band-
pass filters that comprise a filter set or spectrum analyser. The extent of the passband
region of a filter's relative attenuation characteristic is a constant percentage of the
midband frequency for all filters of a given bandwidth. An instrument complying with the
requirements of this International Standard may contain any number of bandpass filters
covering any desired frequency range.
1.2 Pe rformance requirements are provided for three filter classes designated class 0,
class 1, and class 2. Allowed tolerances increase as the class number increases.
rf
1.3 Bandpass filters complying with the pe ormance requirements of this standard may
be part of various measurement systems or may be an integral component of a specific
instrument and shall operate in real time. Performance requirements apply to any method
that is selected by the manufacturer to implement the design of the filters.
1.4 Instruments complying with the requirements of this standard are capable of provid-
ing frequency-band-filtered spectral information for a wide variety of signals, for example,
time-varying, intermittent, and steady; broadband and discrete frequency; and long and
short durations. For applications involving transient signals, different realizations of filters
meeting the requirements of this standard may give different results.
2 Normative references
The following normative documents contain provisions which, through reference in this
text, constitute provisions of this International Standard. At the time of publication, the
editions indicated were valid. All normative documents are subject to revision, and pa rties
to agreements based on this International Standard are encouraged to investigate the
possibility of applying the most recent editions of the normative documents indicated
below. Members of the IEC and ISO maintain registers of currently valid International
Standards.
IEC 50(801): 1994, International Electrotechnical Vocabulary (1EV) - Chapter 801:
Acoustics and electro-acoustics
IEC 651: 1979, Sound level meters
Amendment 1: 1993
IEC 801-2: 1991, Electromagnetic compatibility for industrial-process measurement and
control equipment - Part 2: Electrostatic discharge requirements
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SIST EN 61260:1998
1260 ©IEC:1995 - 9 -
Electromagnetic compatibility for industrial-process measurement and
IEC 801-3: 1984,
control equipment - Part 3: Radiated electromagnetic field requirements
IEC 804: 1985, Integrating-averaging sound level meters
Amendment 1, 1989
Amendment 2, 1993
ISO 266: 1975, Acoustics - Preferred frequencies for measurements
OIML: 1978, Vocabulary of legal metrology - Fundamental terms
3 Definitions
For the purpose of this International Standard, the following definitions apply.
NOTE – For definitions of additional terms in this standard, reference should be made to IEC 50(801) and
the OIML Vocabulary of legal metrology.
3.1 bandpass filter: Filter with a single transmission band (or passband with small
relative attenuation) extending from a lower bandedge frequency greater than zero to a
finite upper bandedge frequency.
Nominal frequency ratio of 2:1; general symbol G.
3.2 octave ratio:
NOTES
1 This standard permits two options, designated base-ten and base-two, for determining an octave-band,
or fractional-octave-band, frequency ratio.
2 For base-ten systems,
3/10 (1)
G = 10
10
3 For base-two systems,
G2 = 2 (2)
4 The base-ten system is preferred.
3.3 bandwidth designator: Reciprocal of a positive integer, including 1, to designate
the fraction of an octave band; symbol 1/b.
Frequency of 1 000 Hz, exactly; symbol fr.
3.4 reference frequency:
3.5 exact midband frequency: In hertz, a frequency that has a specified relationship to
the reference frequency such that the ratio of the exact midband frequencies of any two
contiguous bandpass filters is the same for all filters in a filter set of a specified
. When the denominator of the bandwidth designator is an odd
bandwidth; symbol fm
number, exact midband frequencies of any filter in a set of filters are determined from:
fm = (Gxlb ) (
fr) (3)
and when the denominator of the bandwidth designator is an even number, exact midband
frequencies of any filter in a set of filters are determined from:
m = (G(2x+1)/(2b)) (fr)
(4)
where x is any integer, positive, negative, or zero.
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1260 ©IEC:1995 - 11 -
NOTES.
1 Exact midband frequencies determined from equation (3) or (4) permit the output of narrow-fractional-
octave-band filters to be combined to yield the band level of a filter of wider-bandwidth with a corresponding
exact midband frequency and corresponding bandedge frequencies.
2 With the base-ten system, midband frequencies included within any 10:1 frequency range are the
same as within any other 10:1 frequency range except for the position of the decimal sign. With the
base-two system, midband frequencies are unique and do not repeat.
3 As examples, for one-third-octave-band filters, the exact midband frequency for the band with a
nominal midband frequency of 5 000 Hz is 5 011,872 Hz to three decimal places by the base-ten system
and 5 039,684 Hz by the base-two system, or a difference of approximately 0,6 %. At a nominal midband
frequency of 50 000 Hz, the exact midband frequency is 50 118,723 Hz by the base-ten system and
50 796,834 Hz by the base-two system, or an approximate difference of 1,4 %.
4 When the denominator of the bandwidth designator is an odd number, one of the filters in a complete
filter set may have a midband frequency of 1 000 Hz. When the denominator of the bandwidth designator
is an even number, the bandedge frequency of one adjacent pair of filters in a complete filter set may be
at 1 000 Hz and therefore none of the filters will have a midband frequency of 1 000 Hz.
5 Exact midband frequencies for octave-band and one-third-octave-band filters are given in table A.1 for
the usual range of audio frequencies.
In hertz, rounded midband frequencies for the
3.6 nominal midband frequencies:
designation of bandpass filters.
3.7 In hertz, frequencies of the lower and upper edges of the
bandedge frequencies:
passband of a bandpass filter such that the exact midband frequency is the geometric
mean of the lower and upper bandedge frequencies; symbols f1 and f2, respectively.
Bandedge frequencies are determined from:
-1/(2b)
fi = (G
) (fm ) (5)
and
(G+1!(2b)) (
=
f2
m) (6)
where
G represents an octave frequency ratio calculated according to equation (1) for base-
ten systems or (2) for base-two systems;
fm is an exact midband frequency determined from equation (3) or (4).
3.8 normalized frequency: For a bandpass filter, ratio of frequency to the exact mid-
band frequency; symbol film.
filter bandwidth: In hertz, for a given filter, upper bandedge frequency f 2 minus the
3.9
corresponding lower bandedge frequency Li calculated from equations (5) and (6).
Bandpass filter for which the nominal ratio of upper bandedge
3.10 octave-band filter:
frequency to lower bandedge frequency is two.
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SIST EN 61260:1998
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1260 © IEC:1995
Bandpass filter for which the ratio of upper band-
3.11 fractional-octave-band filter:
is an octave ratio raised to an exponent
1
edge frequency f2 to lower bandedge frequency f
equal to the applicable bandwidth designator.
NOTE – In symbols, a bandedge frequency ratio is f2/f, = Gvb.
In decibels, for a bandpass filter, at any frequency, the level
3.12 filter attenuation:
of the time-mean-square input signal minus the level of the indicated time-mean-square
A.
output signal, with both signal levels relative to the same reference quantity; symbol
in , in decibels, is represented by:
NOTE – In symbols, a time-mean-square input signal level L
2
/T) T V, (t) dt]l Vô) dB
Lin = 101g I[(1 (7)
J
0
where
t;
(t) is the instantaneous input signal as a function of time
Vin
is the elapsed time for integration;
T
V0 is an appropriate reference quantity such as 20 µV.
A corresponding expression applies for the level of the time-mean-square output signal.
In decibels, for all bandpass filters in an instrument,
3.13 reference attenuation:
nominal filter attenuation in the passband as specified by the manufacturer for determining
relative attenuation; symbol
Aref•
In decibels, for a bandpass filter, at any frequency, filter
3.14 relative attenuation:
attenuation minus the reference attenuation; symbol AA.
relative attenuation EA(f/f m ), in decibels, is determined from:
NOTE – At any normalized frequency 111m ,
DA(f/fn) = A(f/f m
) – Aref
(8)
where
f/m;
A (f/fm) is the filter attenuation at normalized frequency
is the reference attenuation.
Aref
are calculated from equation (3) or (4).
Exact midband frequencies fm
effective bandwidth: For constant-amplitude sinusoidal electrical input
normalized
3.15
signals, integral over normalized frequency of the ratio of the time-mean-square signal
indicated by the readout device at the output of the filter set to the time-mean-square input
signal; the ratio of time-mean-square signal is normalized by multiplying by a constant
Aref
is the reference attenuation, in decibels; symbol Be.
equal to 100,1 where A
ref
NOTE – The analytical expression for normalized effective bandwidth is given in 4.5.2.
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SIST EN 61260:1998
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1260 ©IEC:1995
reference bandwidth: For a bandpass filter, ratio of filter bandwidth to
3.16 normalized
the exact midband frequency; symbol Br.
Br is determined from:
NOTE - Normalized reference bandwidth
i )/fm
- t (9)
= +1/(2b ) - G-11(2b)1
[G
3.17 filter integrated response: In decibels, ten times the logarithm to the base 10 of
the ratio of the normalized effective bandwidth of a filter to the normalized reference
bandwidth; symbol AB.
NOTE - The analytical expression for AB is given in 4.5.1.
range: In decibels, one of the available level ranges specified by
3.18 reference level
the manufacturer for testing electrical performance characteristics.
input signal level: In decibels, level of the input signal, specified by the
3.19 reference
manufacturer, on the reference level range.
In decibels, for a bandpass filter on any level range, output signal
3.20 level difference:
level minus the input signal level plus the nominal attenuation of the level range control, if
applicable.
3.21 reference level difference: In decibels, on the reference level range, level
difference for an input signal at the applicable reference input signal level at the midband
frequency.
3.22 level linearity error: In decibels, on any level range, a level difference at the mid-
band frequency minus the reference level difference.
3.23 linear operating range: In decibels, for a stated filter bandwidth and a stated level
range, the extent of steady sinusoidal input signal levels over which level linearity errors
are maintained within specified tolerances from a lower boundary to an upper boundary.
range control: A device for adjusting the sensitivity of an instrument in
3.24 level
response to changes in the level of the input signal in order to maintain the overall
operation of the instrument within the linear operating range.
3.25 measurement range: In decibels, for any nominal midband frequency, the upper
boundary of the input signal level for the linear operating range on the least-sensitive level
range minus the lower boundary of the input signal level for the linear operating range on
the most-sensitive level range.
3.26 analogue filter: Filter that operates continuously on the input signal to produce a
filtered output.
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1260 ©IEC:1995
3.27 sampled-data filter: Computational process that operates on samples of the input
signal to produce a filtered output.
3.28 digital filter: Subset of sampled-data filters that operates on digitized samples of
input data.
3.29 real-time operation: An operational mode or capability of a sampled-data filter
system to produce bandpass-filtered output signal levels and for which, on average, the
computing associated with each sampling interval is completed in a time period less than
or equal to the sampling interval such that all input data are processed within the sampling
interval and all samples of an input signal contribute with equal weight to the resulting
filtered output signal levels.
frequency components: Spurious frequency components in the output
3.30 aliased
signal from a sampled-data bandpass filter that result when a time-varying, but
continuous, input signal is sampled at a rate that is too low compared with the highest
frequency component of the input signal.
3.31 anti-alias filter: Low-pass filter to reduce the contribution of aliased frequency
components in the output to an insignificant level.
4 Performance requirements
4.1 General
Electrical response characteristics specified in this standard for octave-band and fractional-
octave-band filters apply under the reference environmental conditions of 4.13.
Any filter design realization, with a base-ten or a base-two octave frequency ratio, may be
utilized providing the resulting instrument complies with all applicable requirements of this
standard.
Nominal midband frequencies
4.2
Octave-band and fractional-octave-band filters shall be identified, or labelled, by nominal
midband frequencies that are suitably rounded values of exact midband frequencies.
Annex A provides exact and nominal midband frequencies for octave-band and one-third-
octave-band filters. A procedure is described for determining the nominal midband
filters with bandwidth designators from 1/4 to 1/24.
frequencies for fractional-octave-band
Reference attenuation
4.3
The manufacturer shall specify the reference attenuation in the passband. The reference
attenuation shall be the same for all filters in a set of filters.
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SIST EN 61260:1998
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4.4 Relative attenuation
4.4.1 For octave-band filters of class 0, 1, or 2, the relative attenuation of any filter shall
be within the limits in table 1 for the minimum and maximum relative attenuations at the
1/1m = S2.
specified values of octave-band normalized frequency
4.4.2 For a fractional-octave-band filter with bandwidth designator 1/b, the high-
corresponding to a finite
frequency fractional-octave-band normalized frequencyS^h(1/b),
relative attenuation limit for the accuracy class shall be calculated, for S2 >_ 1, from:
1 + [(G1/(2b) - 1)/(G 1
-
(10)
12 1)](S2 - 1)
n
h(1/b) =
For S2 < 1, the low-frequency fractional-octave-band normalized frequency 01(1/b) shall be
calculated from:
n
1(1 /b) = 1 /nh(1/b)
for the same limit on relative attenuation.
NOTE — Annex B provides an example calculation of the normalized frequencies at the breakpoints for the
limits on minimum and maximum relative attenuation for one-third-octave-band filters.
a and S2b given in table 1 for octave-band filters, or
4.4.3 At normalized frequencies O
between comparable normalized fractional-octave-band frequencies calculated according
to equation (10) or (11) for fractional-octave-band filters, the limit for relative attenuation
shall be determined from the linear interpolation relation:
AAx at normalized frequency S2x
AA f2 /Ig
AAx = AA a + [AA b - a ( SZ b
][ 1g ( /na) /Da)] (12)
x
where
AAa is a relative attenuation limit at normalized frequency S2a;
is a relative attenuation limit at normalized frequency S2b.
AAb
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SIST EN 61260:1998
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1260 © IEC:1995
Table 1 - Limits on relative attenuation for octave-band filters
Minimum; maximum attenuation limits
Normalized
frequency dB
LI
f/fm = Filter class
1 2
0
-0,15; +0,15 -0,3; +0,3 -0,5; +0,5
G0
Gt118
-0,15; +0,2 -0,3; +0,4 -0,5; +0,6
Gt114
-0,3; +0,6 -0,5; +0,8
-0,15; +0,4
Gt3/8
-0,15; +1,1 -0,3; +1,3 -0,5; +1,6
-0,15; +4,5 -0,3; +5,0 -0,5; +5,5
>G-112
0t 1i2'
+1,6; +5,5
+2,3; +4,5 +2,0; +5,0
Gt1
+18,0; +.0 +17,5; +co. +16,5; +.0
+42; +o. +41; +.0
Gt2 +42,5; +co
+oo
Gt3 +62; +00 +61; +00 +55;
+75; +.0 +70; +.0 +60; +.0
2G+4
4
At frequencies less than the lower band-edge frequency and greater than the
*
upper band-edge frequency, the limit on maximum relative attenuation is + .0; see
figure 1.
4.4.4 Figure 1 illustrates the limits on minimum and maximum relative attenuation for
an octave-band filter. The figure also shows the discontinuous changes in minimum and
maximum relative attenuation at the band-edge frequencies and the linear variation of
relative attenuation limits between the breakpoint normalized frequencies of table 1.
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SIST EN 61260:1998
1260 --23- 23 -
© IEC:1995
- 2
0
m
2
v
è
4
6
8
-20 10 I
- G'
G
m
^ 0
20
c
o
v
^
a^
40
ô
^
>
^
�0
m 60
+a0 +oo
• l ,1 t , 1 , , ^
80- I
s 63 62 O
G G 4 G' G G' GZ G' G4 Gs
Normalized frequency, f/f,,, (logarithmic scale)
IEC 66305
Figure 1 - Illustration of minimum and maximum limits on relative
attenuation for class 1 octave-band filters
4.5 Filter integrated response
4.5.1 For a bandpass filter, filter integrated response AB, in decibels, shall be deter-
mined from
(13)
AB = 10 Ig(Be/Br )
where
Be is the normalized effective bandwidth;
is the normalized reference bandwidth from equation (9) for the same midband
Br
frequency.
m , normalized effective bandwidth is
4.5.2 For any filter of exact midband frequency f
represented by:
00
10"0,1 oA(ffimi
(14)
d (f/fm ) 8e =
f
o
where
is the continuous relative-attenuation filter response, in decibels. In practice,
AA(f/fm)
the integral in equation (14) is evaluated numerically; see 5.4.
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SIST EN 61260:1998
1260 ©IEC:1995 - 25 -
4.5.3 For each bandpass filter in an instrument, the filter integrated response shall not
exceed ±0,15 dB, ±0,3 dB, and ±0,5 dB for classes 0, 1 and 2 instruments, respectively.
4.6 Linear operating range
4.6.1 For all filter bandwidths, and for the flat frequency response if provided, and for
each available level range, the level linearity errors on the linear operating range shall
not exceed ±0,3 dB, ±0,4 dB, and ±0,5 dB respectively over linear operating ranges of at
least 60 dB, 50 dB, and 40 dB for classes 0, 1, and 2 filters, respectively.
4.6.2 Level ranges, if more than one is provided, shall overlap such that the linear operat-
ing ranges overlap by at least 40 dB for class 0 and class 1 filters and at least 30 dB for
class 2 filters.
4.6.3 For filters with more than one level range, a reduced linear operating range is
allowed on the most sensitive range, provided it is not the reference level range.
4.6.4 For filters where a display is an integral component, or when the filter output is
transferred to an external display or to another system, and the range of the display is
greater than the linear operating range, the manufacturer shall specify the tolerances on
level linearity that are maintained outside the linear operating range.
4.7
Real-time operation
The manufacturer shall state the bandwidth designators and corresponding frequency
ranges for which the level of the output signal in response to a constant-amplitude
sinusoidal input signal, the logarithm of the frequency of which is varied at a constant rate,
is within ±0,3 dB of the theoretical output signal level for class 0 and class 1 instruments,
and within ±0,5 dB for class 2 instruments. The expression for the theoretical output signal
level in response to a constant-amplitude swept-frequency sinusoidal input signal is given
in 5.6.
4.8 Anti-alias filters
The manufacturer shall include anti-alias filters, analogue and digital as appropriate, in a
sampled-data or digital filter system. Anti-alias filters shall minimize interference between
an input signal and the sampling process that would create aliased frequency components
of the input signal and cause the relative attenuation response of a filter to exceed the
greatest value of the applicable minimum limits of table 1.
4.9 Summation of output signals
For a sinusoidal input signal at any frequency between two consecutive octave or
fractional-octave midband frequencies, the difference between (a) the level of the input
signal minus the reference attenuation and (b) the level of the sum of the time-mean-
square output signals from various filters of specified filter bandwidth shall not exceed
±1,0 dB; +1,0 dB, -2,0 dB and +2,0 dB, -4,0 dB for classes 0, 1, and 2 instruments,
respectively.
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4.10 Flat frequency response
If an instrument has a range of frequency-independent (i.e. "flat") transmission, the
manufacturer shall state a range of frequencies over which the relative attenuation is
within ±0,15 dB, ±0,3 dB, and ±0,5 dB of the relative attenuation at the reference
frequency for classes 0, 1, and 2 instruments, respectively. The reference attenuation for
measurements of relative attenuation with flat frequency response is the same as that for
the relative attenuation of a bandpass filter.
4.11
Maximum input signal
The manufacturer shall state the maximum root-mean-square voltage of the sinusoidal
input signal on each level range for which every filter in the instrument meets the require-
ments of this standard.
4.12
Terminating impedances
If applicable, the manufacturer shall state the input and output terminating impedances
necessary to ensure proper operation of the instrument.
4.13
Reference environmental conditions
Reference environmental conditions include an ambient air temperature of 20 °C, a
relative humidity of 65 %, and an atmospheric pressure of 101,3 kPa.
4.14 Sensitivity to various environments
4.14.1 Ambient air temperature
Over the minimum range of ambient temperature from 0 °C to + 50 °C, the relative
attenuation for any filter available in the instrument and at the nominal midband frequency
shall not deviate from the relative attenuation at the same frequency under reference envi-
ronmental conditions by more than ±0,15 dB, ±0,3 dB, and ±0,5 dB for classes 0, 1, and 2
instruments, respectively.
4.14.2 Relative humidity
The manufacturer shall state the range of relative humidity and corresponding air
temperature over which the instrument can operate continuously. After a 24 h exposure to
the humid atmosphere at a relative humidity of 75 %, and at an ambient air temperature
of +40 °C and without condensation on internal components of the instrument under test,
the relative attenuation at the nominal midband frequency for any filter available in the
instrument shall not deviate from the relative attenuation at the same frequency under
dB for
reference environmental conditions by more than ±0,15 dB, ±0,3 dB, and ±0,5
classes 0, 1, and 2 instruments, respectively.
4.14.3 Alternating magnetic fields
The influence of magnetic fields alternating at 50 Hz or 60 Hz (and at harmonics of
the fundamental frequency) on the operation of a filter set shall be reduced as far as
practicable.
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SIST EN 61260:1998
1260 ©IEC:1995 – 29 –
4.14.4 Electrostatic discharges
The influence of electrostatic discharge on the operation of a filter set shall be reduced as
far as practicable.
4.14.5 Radio-frequency electromagnetic fields
The influence of radio-frequency electromagnetic fields on the operation of a filter set shall
be reduced as far as practicable.
4.15 Power supply check
For instruments that require a battery power supply, the manufacturer shall provide a
suitable means to check that the power supply is adequate, at the time of checking, to
operate the instrument according to all requirements of this standard.
5 Test methods
5.1 General
This clause describes methods of tes
...
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