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14
Glossary and Formulas
LxT Manual
High Pass
: A frequency filter that permits signals to pass
through that have frequencies above a certain fixed
frequency, called a
cutoff frequency.
It is used to remove
lower frequencies.
Bandpass
: A frequency filter that permits signals to pass
through that have frequencies above a certain fixed
frequency, called a lower cutoff frequency, and below a
certain fixed frequency, called an
upper cutoff frequency
.
The difference between the two cutoff frequencies is called
the
bandwidth
. It is used to discriminate against both lower
and higher frequencies so it passes only a band of
frequencies.
Octave band
: A bandpass frequency filter that permits
signals to pass through that have a bandwidth based on
octaves. An
octave
is a doubling of frequency so the upper
cutoff frequency is twice the lower cutoff frequency. This
filter is often further subdivided in 1/3 and 1/12 octaves (3
and 12 bands per octave) for finer frequency resolution.
Instruments with these filters have a sufficient number of
them to cover the usual range of frequencies encountered in
sound and vibration measurements.The frequency chosen to
describe the band is that of the center frequency.
Frequency Filter - Weighted
A special frequency filter that adjusts the amplitude of all
parts of the frequency spectrum. It can be composed of one
or more of the following types:
A-Weighting
: A filter that adjusts the levels of a frequency
spectrum in a way similar to what the human ear does when
exposed to low levels of sound. This weighting is most often
used for evaluation of environmental sounds. See table
below.
B-Weighting
: A filter that adjusts the levels of a frequency
spectrum in a way similar what the human ear does when
exposed to moderate levels of sound. This weighting is
seldom used. See table below.
C-Weighting
: A filter that adjusts the levels of a frequency
spectrum in a way similar to what the human ear does when
exposed to high levels of sound. This weighting is most
often used for evaluation of equipment sounds. See table
below.
Содержание SoundExpert LxT
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Страница 55: ...4 18 Measurement Settings Tabs LxT Manual...
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Страница 110: ...LxT Manual Certification 7 17...
Страница 143: ...11 6 Control Panel Data Explorer LxT Manual...
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Страница 206: ...LxT Manual Technical Specifications A 9 Typical Z Weight Frequency Response...
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