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Short History PDF 16 MB
Worldwide First Acoustic Images
Origin of the Name "Acoustic Camera"
Remark 2023: At the "Hannover Industrie" fair 1997 we presented a "16-channel acoustic interference measurement station". A reporter from the Berliner Zeitung, Dr. Michael Ochel, visited the stand. "I'm interested in new technologies. Can you please tell me, what this is?" I told him, that the device can produce acoustic images and films. And he answered: "If it is so clear, why didn`t you call it Acoustic Camera?" So we did. Find his story here in the press-directory 1997. More about historical records of the Acousic Camera see here.
An authentic document of this time ist the application for the "Philip Morris Forschungspreis" dated to October 1997 (PDF). Find first images and movies here. The following flyer gives some impressions. It is mutually produced in the year 1998, sometimes after the "Funkausstellung 1997" fair beyond Funkturm Berlin.
The Acoustic Camera consists of a PC-based 16-channel data recorder and the software PSI-Tools (Parallel and Serial Interference Tools) to reconstruct acoustic images from microphone records. PSI-Tools in the minute is the most selective tool for acoustic excitment mapping in the world. The new core algorithm, called H-Interference Transformation (HIT), is nearly ten times more accurate then other, known algorithms. Thus, PSI-Tools was the first system, producing acoustic images going around the world.
PSI-Tools reconstructs the time-function for each pixle of a noise image. Then PSI-Tools takes the effective value of these time function to set the color of a pixle.
PSI-Tools runs under Microsofts Windows95. For details see software and function of the tool. Find a description of PSI-Tools here.
PSI-Help File System
It includes a powerfull help-file system. Download the help-file and PSI-Tools here.
The channel data comes from 16 microphones. They cary very different signals. The differences allow to transform the channel data into the excitment location map using the authors Interference Transformation (HIT).
Hardware of first Acoustic CamerasThe portable PC-Pentium with analog-digital converter, preamplifier and microphone array allows to sample 16 channels in parallel with sampling rates until 50 or 100 kSps.
a) b) c)
a) Portable PC
The PC-Pentium includes a full size AT-bus-slot for the 12-bit analog-digital converter card UEIDAC WIN30-DS, see hardware.
b) 16-Channel Microphone Array
For measurements up to a distance of 30 meters we used calibrated 1/2" measurement electret-microphones MK250 from Mikrotech Gefell with a frequency range from 100 Hz to 20 kHz. To access defined locations for the 16 measuring microphones, they are arranged within an orthogonal array with a grid size of 30 cm. To avoid reflections, the microphone membranes have been placed planar to the front wall of the device. Included in the array is the 16-channel, 32-bit per channel programmable preamplifier (d), see arrays.
c) 16-Channel Soft-Controlled Preamplifier:
For more details see hardware.
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file created Oct. 17, 1997; 14:38