Comparison of instruments for acoustic emission

Acoustic emission has been evolving since the beginning of the technology until now. Acoustic emission instruments have also been advancing. There is a simple division of this development into stages, you can see.

The first stage, in 1965, the United States Dunegan launched the first commercial acoustic emission instrument, until 1983 are basically pure analog technology to achieve the acoustic emission instrument, but also the first generation of acoustic emission instrument;

The second generation of acoustic emission instrument, 1983~1994, the U.S. PAC's SPARTAN-AT began to introduce the microprocessor, and the sound Acoustic emission system modular, partially digitized;

Third-generation acoustic emission instrument, 1994~2003, the United States DW, the United States PAC and Germany Vallen will acoustic emission instrument comprehensive digitization, acoustic emission transducer received signals through the amplifier amplification directly after the AD converter dedicated to digital signals, and then use the digital circuit hardware to extract the characteristics of the parameter, and in accordance with the PDT, HDT, HLT and other time constants to extract the acoustic emission waveform;

The fourth generation of otoacoustic emission instrumentation, 2003~2015, the U.S. PAC will be 18bit high-speed ADC introduced into the PCI bus otoacoustic emission card, opened up the 18bit high-precision acquisition, in addition to the characteristic parameters and waveforms, but also enabled the waveform streaming function that contains all the original information. During this period, the USB interface acoustic transmitter also began to appear, and gradually developed from USB2.0 to USB3.0, the bus transfer speed also increased from 40MB to 400MB;

The fifth generation of acoustic transmitter, 2015 so far, China's Pengxiang company introduced a PCIE bus acoustic transmitter card, a single card with 8 channels, 18bit30M samples per channel, and a frequency bandwidth As high as 1kHz~5MHz, and the use of PCIE x8 times the speed of transmission, card transmission bandwidth up to 3GB/s, the fourth generation of otoacoustic emission instrument existing transmission bottleneck has been solved. In addition to real-time hardware extraction of acoustic emission parameters and waveforms, the waveform streaming function can also be collected and transmitted in real time at full speed without bandwidth limitation. At the same time, suitable for distributed detection of Gigabit network interface network acoustic emission instrument began to appear, and will gradually to fiber optic transmission development, to achieve long-distance distributed acoustic emission detection.

Divided from the frequency:

In the first stage, Dunegan et al. increased the experimental frequency of otoacoustic emission to 100kHz-1MHz;

In the second stage, the signal bandwidth of otoacoustic emission instrument was increased to 100kHz~1.2MHz;

In the third stage, the signal bandwidth of otoacoustic emission instrument was widened to 1kHz~ 2MHz;

In the fourth stage, the signal bandwidth of the acoustic emission instrument is increased to 1kHz~3MHz;

In the fifth stage, the signal bandwidth of the acoustic emission instrument is increased to 1kHz~5MHz;

With the development of the PCIE bus technology and the high-speed ADC, the acoustic emission instrument with 10MHz signal frequency or even higher frequency may also appear in the future In fact, as early as October 1989, Japan's Fuji Ceramics produced a 10MHz standard acoustic emission sensor (model REF10M).

From the way of signal acquisition and analysis,

The first stage, the acoustic emission instrument used pure analog technology;

The second stage, microprocessors were introduced into the acoustic emission instrument, began to form a mixture of analog and digital circuits of the instrument, the signal analysis is mainly on the characteristic parameters;

The third stage, the acoustic emission instrument in the signal amplification In the third stage, the acoustic emission instrument in the signal amplification ADC after the full digitalization, in addition to the characteristic parameters, but also appeared in the acoustic emission waveform means of analysis;

The fourth stage, acoustic emission instrument began to PCI and USB bus, ADC sampling accuracy and sampling rate can be greatly improved, in addition to the characteristic parameters and the waveform, but also contains all the original information stored in the waveform stream signal. Only due to the bus bandwidth limitations and can not get all the multi-channel waveform stream file;

The fifth stage, the acoustic emission instrument began to use the PCIE bus, the fourth generation of instruments existed in the bus bandwidth bottleneck has been broken, in addition to the characteristics of the parameters and acoustic emission waveforms, the original waveform stream file is also able to be all the real-time transmission and preservation.

Acoustic emission meter as a typical virtual instrument, with the development of computer bus technology and improve is also an inevitable trend.