spaschal on DSK3GDR082PROD with CFR

Pt. 36, App. A

14 CFR Ch. I (1-1-19 Edition)

allowance does not eliminate the requirement of including microphone extension cables when performing the pink noise recording in section A36.3.9.5.
A36.3.6.4 For analog tape recordings, the
amplitude fluctuations of a 1 kHz sinusoidal
signal recorded within 5 dB of the level corresponding to the calibration sound pressure
level must not vary by more than Section0.5 dB
throughout any reel of the type of magnetic
tape used. Conformance to this requirement
must be demonstrated using a device that
has time-averaging properties equivalent to
those of the spectrum analyzer.
A36.3.6.5 For all appropriate level ranges
and for steady sinusoidal electrical signals
applied to the input of the measurement system, including all parts of the microphone
system except the microphone, at one-thirdoctave nominal midband frequencies of 50
Hz, 1 kHz and 10 kHz, and the calibration
check frequency, if it is not one of these frequencies, the level non-linearity must not
exceed Section0.5 dB for a linear operating range of
at least 50 dB below the upper boundary of
the level range.
NOTE 1: Level linearity of measurement
system components may be tested according
to the methods described in IEC 61265 as
amended.
NOTE 2: Microphone extension cables configured in the field need not be included for
the level linearity determination.
A36.3.6.6 On the reference level range, the
level corresonding to the calibration sound
pressure level must be at least 5 dB, but no
more than 30 dB less than the upper boundary of the level range.
A36.3.6.7 The linear operating ranges on adjacent level ranges must overlap by at least
50 dB minus the change in attenuation introduced by a change in the level range controls.
NOTE: It is possible for a measurement system to have level range controls that permit
attenuation changes of either 10 dB or 1 dB,
for example. With 10 dB steps, the minimum
overlap required would be 40 dB, and with 1
dB steps the minimum overlap would be 49
dB.
A36.3.6.8 An overload indicator must be included in the recording and reproducing systems so that an overload indication will
occur during an overload condition on any
relevant level range.
A36.3.6.9 Attenuators included in the measurement system to permit range changes
must operate in known intervals of decibel
steps.
A36.3.7 Analysis systems.
A36.3.7.1 The analysis system must conform to the specifications in sections
A36.3.7.2 to A36.3.7.7 for the frequency
bandwidths, channel configurations and gain
settings used for analysis.

A36.3.7.2 The output of the analysis system
must consist of one-third octave band sound
pressure levels as a function of time, obtained by processing the noise signals (preferably recorded) through an analysis system
with the following characteristics:
(a) A set of 24 one-third octave band filters,
or their equivalent, having nominal midband
frequencies from 50 Hz to 10 kHz inclusive;
(b) Response and averaging properties in
which, in principle, the output from any onethird octave filter band is squared, averaged
and displayed or stored as time-averaged
sound pressure levels;
(c) The interval between successive sound
pressure level samples must be 500 ms Section5 milliseconds(ms) for spectral analysis with or
without slow time-weighting, as defined in
section A36.3.7.4;
(d) For those analysis systems that do not
process the sound pressure signals during the
period of time required for readout and/or resetting of the analyzer, the loss of data must
not exceed a duration of 5 ms; and
(e) The analysis system must operate in
real time from 50 Hz through at least 12 kHz
inclusive. This requirement applies to all operating channels of a multi-channel spectral
analysis system.
A36.3.7.3 The minimum standard for the
one-third octave band analysis system is the
class 2 electrical performance requirements
of IEC 61260 as amended, over the range of
one-third octave nominal midband frequencies from 50 Hz through 10 kHz inclusive
(incorporated by reference, see Section 36.6).
NOTE: IEC 61260 specifies procedures for
testing of one-third octave band analysis
systems for relative attenuation, antialiasing filters, real time operation, level
linearity, and filter integrated response (effective bandwidth).
A36.3.7.4 When slow time averaging is performed in the analyzer, the response of the
one-third octave band analysis system to a
sudden onset or interruption of a constant
sinusoidal signal at the respective one-third
octave nominal midband frequency, must be
measured at sampling instants 0.5, 1, 1.5 and
2 seconds(s) after the onset and 0.5 and 1s
after interruption. The rising response must
be Section4 Section1 dB at 0.5s, Section1.75 Section0.75 dB at 1s, Section1
Section0.5 dB at 1.5s and Section0.5 Section0.5 dB at 2s relative
to the steady-state level. The falling response must be such that the sum of the output signal levels, relative to the initial
steady-state level, and the corresponding rising response reading is Section6.5 Section1 dB, at both 0.5
and 1s. At subsequent times the sum of the
rising and falling responses must be Section7.5 dB
or less. This equates to an exponential averaging process (slow time-weighting) with a
nominal 1s time constant (i.e., 2s averaging
time).
A36.3.7.5 When the one-third octave band
sound pressure levels are determined from

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