Microphone Arrays. - PM Instrumentation

Microphone Arrays. - PM Instrumentation
Individually configurable system.
Microphone Arrays.
Ring Arrays for acoustic labs.
Star Arrays for open-air applications.
Sphere Arrays for interiors.
Since the acoustic camera is using beamforming
technology the following arrays are designed to
serve the specific needs of the user and its appli­
cation. However, if the mentioned arrays do not
serve your special case you can use some of our
freely configurable microphone bundles to design
your own array.
All arrays include a video camera and microphones
which are advanced disturbance tolerant with 1/4’
symmetrically buffered electret pressure receivers.
The material used for the microphone ring is
carbon fiber and carbon mesh for the spherical
array.
GFaI’s partnership with SenSound (USA) allows
GFaI to offer a comprehensive acoustic imaging
package. The existing acoustic camera Beam­
forming hardware platform now seamlessly
integrates with SenSound’s Nearfield Acoustic
Holography software by using the free configurable
microphones. For more information on Holography
please see also: www.sensound.com
Microphone Arrays Ring 36
and Ring 48
Ring 36/48 Array
for the acoustic lab.
Type
Ring 36
Ring 48
Size
Ø 0.35 m
Ø 0.75 m
Recommended measurement distance
0.4 m to 2 m
0.7 m to 5 m
Number of 1/4‘ electret
pressure microphones
36
48
Maximum sound level
130 dB (standard)
130 dB (standard)
Recommended mapping
frequency
1 kHz to 20 kHz (50 kHz)
400 Hz to 20 kHz
The Ring 48 Array is the preferred choice for a
broad range of applications.
When measuring higher frequencies and smaller
components an array of smaller diameter with 36
microphones may be favored.
Free configurable 24 channel
microphone bundle (10Hz-10kHz)
Sphere 48 Array
Sphere 48/120 Array
for measurements in interiors.
The sphere design is a 48 to 120 channel mea­
surement system for small devices, for measure­
ments in very confined spaces and for high
frequencies. The microphone construction is made
from carbon fiber material and guarantees maxi­
mum acoustic transparency. The design minimizes
aliasing effects and partial reflections. The array
has extremely small microphones to reduce
distortions of the wave field.
The array can be set up at the opti­mum angle on
the included tripod. Backward attenuation is high
enough to allow an all-around mapping. This
makes the system ideally suited ­for measurements
in vehicle interiors and all applications in the room
and building acoustics.
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Sphere 120 Array
Type
Sphere 48
Sphere 120
Size
Ø 0.35 m
Ø 0.6 m
Recommended measurement distance
0.3 m to 1.5 m (longer
distances possible for
frequencies >3kHz)
0.3 m to 1.5 m (longer
distances possible for
frequencies >3kHz)
Number of 1/4‘ electret
pressure microphones
48
120
Maximum sound level
130 dB (standard)
130 dB (standard)
Recommended mapping
frequency
1 kHz to 10 kHz
600 Hz to 10 kHz
Individually configurable system.
Microphone Arrays.
Spiral 120 Array
Star 48 Array
for long distances and low
frequency application.
The star-shaped array with 48 measurement
channels has been designed for measurements
over longer distances. The maximum span width­
is 3.40 m. Thanks to the folding mechanism the
en­tire system can be easily transported in a
standard station wagon and quickly set up within a
few minutes.
Star 48 Array
Type
Star 48
Spiral 120
Size
Max span width 3.4 m
2x2m
Recommended measurement distance
3 m to 300 m
3 m to 150 m
Number of 1/4‘ electret
pressure microphones
48
120
Maximum sound level
130 dB (standard)
130 dB (standard)
Recommended mapping
frequency
100 Hz to 7 kHz (>6dB)
200 Hz to 20 kHz
The Star 48 Array is non-planar and the patented
construction guarantees a maximum backward
attenuation which is a prerequisite for measure­
ments in environments that are not disturbancefree. Pass-by measurement is featured. The
included 3 m tripod is fitted with a 3-way head and
allows for a setup at the optimum angle.
Spiral 120 Array
for wind tunnel application.
The Spiral 120 Array has been developed for the
measurement of large objects and special ap­pli­
cations, e.g. in a wind tunnel. It achieves an
excellent acoustic dynamic range.
Individually configurable system.
Data Recorder.
Data Recorder mcdRec 721.
Data Recorder mcdRec
The newest generation data recorder has been
designed especially for high channel count appli­
cation and harmonizes best with the acoustic
camera in any laboratory and in the field. Featuring
a modular system configuration it provides a
remarkably high data transfer rate and a high level
of interface connectivity, e. g. Ethernet. With its
newly developed design the data recorder can
easily be adapted to changing requirements or
new technical developments.
Technical details mcdRec
•48 to 144 microphone channels in a 10” rack
(24 channels per card)
•sampling frequency from 48 kHz to 192 kHz
for each analog channel and up to 6 MS/s
•Embedded PC with Windows XP (embedded)
•Network capability
•Gigabit Ethernet Interface, transfer rate 20
MByte/s
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Measurement cards
From left
to right
Type of card
Number of
channels
Input
1
cPCI Analog Measurement Card
for microphone arrays
24 analog
diff. 2.5 ± 1 V
2
cPCI Analog Measurement Card
for AC/DC measurements
8 analog
diff. ± 10 V
3
cPCI Analog Measurement Card
for TEDS sensors, 30 bit adc
4 analog
4.7 mA / 1 to 23 V
4
cPCI Digital isolated Measurement
Card with Remote Connector
12 digital
-7 V to + 12 V
Individually configurable system.
Software NoiseImage.
NoiseImage enables you to freely choose and display a variety of analyses
simultaneously: time-, frequency-, rpm- and space-selective.
Analysis methods
and special features.
Software NoiseImage: acquisition,
evaluation and storage of data,
acoustic images and movies.
When developing the software great attention has
been paid to ease of use, to covering the important
questions the user has to answer and to the overall
quality and stability of the software. The basic,
intuitive and graphically oriented user interface
has been continuously upgraded. User experience
and recommendations resulting from more than
eight years of practical application have influenced
the development of NoiseImage and led to many
new features within the software architecture.
The complete software is now based on a plug-in
concept. Extending the basic module every func­
tion­al plug-in brings along its own graphical
interface and its own tools. The users can decide
which functions they really need and can thus
arrange a tailor-made software system.
• Extended preview in record module
• Oscilloscope for time and spectral functions
• A-, B-, C-standard weightings
• Freely configurable Butterworth filter bank
• Acoustic photos 2D and 3D
• Acoustic movies 2D and 3D
(including automatic overlay of optical video)
• Frequency-selective acoustic photo
(SpectralPhoto2D and 3D)
• Space-selective spectrum and spectrogram
• Space-selective order spectrum and ordergram
• Channel data export into ArtemiS
from HEAD-Acoustics and MATLAB®
from The MathWorks, TXT, WAVE etc.
• Maximum buffer time at 48kHz
sampling rate is 173s
• Broadband, short time analysis using time/
frequency domain beamforming
• Additional methods like zero-padding,
MAX-method, “delete Autocorrelation”,
coherence filtering
Measuring acoustic emissions from truck
with Ring Array – set-up and 3D result.
All modules of NoiseImage enable you to map onto 2D
optical photo or 3D-CAD-model of the measured object
Acoustic Movie 2D of a wind turbine
and Acoustic Photo 3D of car interior
including spectral analysis.
Acoustic Photo 2D/3D
Acoustic Movie 2D/3D
Spectral Photo 2D/3D
• High resolution acoustic map
(more than 20MPixel)
• Location-selective listening into the
acoustic map
• Frequency-selective Acoustic Photo
using band filter
• Frequency- and time-selective
Acoustic Photo directly from
selected region in the spectrogram
• Adjustable contrast of Acoustic
Photos (colour palette and
pressure- or dB-range)
• Export of Acoustic Photos to Text,
JPG, PNG or BMP-format
• To AVI-Format in slow motion
(without sound) and in realtime
(including sound) in 2D and 3D
• High time resolution, acoustic ultra
slow motion up to several thousand
acoustic frames per second
• Mapping of acoustic frames onto
the recorded optical video
(movie on movie-function)
• Location-selective listening into
the Acoustic Movies
• Adjustable contrast of Acoustic
Movies (colour palette and
pressure- or dB-range)
• Export of individual frames from
the Acoustic Movie to Text, JPG,
PNG or BMP-format
• To AVI-Format in slow motion
(without sound) and in realtime
(including sound) in 2D and 3D
• Manual selection of a frequency
band and immediate update of
Photo2D and 3D
• Easy manipulation of the width of
the selected frequency band using
the mouse
• Continuous shifting of individually
marked frequency band
• View of frequency and amplitude
axis in linear as well as in
logarithmic scalings
• Simple and fast visual evaluation of
third octave bands
• Sound pressure level display for
individual third octave bands
• Export of the Acoustic Photo to
Text, JPG, PNG or BMP-format
• To AVI-Format in slow motion
(without sound) and in realtime
(including sound) in 2D and 3D
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