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Acoustic Emission Sensors with Integrated Measuring System - Overview

4nd Generation:: G4-ISM, G4-SPE, G4-DUAL, G4-MID

Operating principle: We have been developing sensors with integrated acoustic emission systems since 2016. The sensor housing contains an analog part, a digital signal processing unit and a web server. The analog part amplifies the sensor signal and forms the logarithmic envelope for data reduction. AE parameters such as arrival time, rise time, signal duration, peak amplitude and energy are extracted from the envelope by the digital signal processing unit. The waveform of the envelope curve can be recorded parallel to the AE parameters. The sensor generates dynamic websites and is connected to a data network either wirelessly (type ISM) or via a single pair cable (type SPE). The control of the sensors and the display of the measurement results take place independently of the hardware and operating system as a web application.

G4-ISM-150 kHz-LiIon-4.2 Ah

Type ISM: The wireless data transmission takes place in the 2.4 GHz ISM band. Built-in Li-Ion or LiFePo4 batteries take over the power supply. In practice, depending on the sensor type, measurement regime, hit rate, ambient temperature and aging of the Li cells, operating times between 24 and 240 hours can be achieved without recharging. In the worst case, the power consumption of a sensor is 91 mW. An obvious benefit is that no cables are required.

Type SPE: Data transmission and power supply take place via Single Pair Ethernet (SPE). Aufgrund ihrer geringen Durchmesser und hohen Flexibilität lassen sich SPE-Kabel leicht verlegen. Cable lengths of up to 1400 m m are possible for point-to-point connections. Multidrop bus lines and / or mid-devices reduce the total cable lengths by up to 10 % compared to conventional central AE systems. When using a mid device, each cable is shorter than the sensor distance. Multidrop bus lines lead to cable lengths that correspond to the transducer spacing. The maximum power consumption of a sensor is less than 105 mW. The SPE solution is independent of interference in the widely used ISM band.

Type DUAL: The dual sensors have both an ISM antenna and SPE connector. They can be used as ISM or SPE sensors and combine the advantages of both types. Disadvantages are the larger construction volume and the shorter operating times.

Mid Device: The mid device perform the following tasks: First, they are the link between the sensors and the browser of any computer. It converts the sensors' proprietary protocols into standardized connections such as WLAN or LTE. Secondly, the synchronization of the sensors in the sub-microsecond range, which is necessary for source location, is improved and, thirdly, a considerable reduction in cable lengths is ensured when using the SPE types.

Technical data applies to all sensors
95 dB
Variable gain
0 ... 20 dB
Smallest amplitude
5 dBae
Greatest amplitude
120 dBae
Analog bandpasses
3 x Bessel 3rd order
Data storage
4 Gbit
Δt error
<1.25 µs
Test signal
N x 36 or 72 Vpp
Coupling surface
Outer casing
Protection class

HINT: For a size comparison, all sensor images show a conventional 150kHz sensor ⌀ 19 x 15 mm on the right.