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5th generation devices will be available soon. They do not require mid devices.
4th generation sensors are obsolete. They are only sold for the expansion of existing measuring systems.

Mid Device of 4th generation

Mid Device G4.1 IP20 with rechargeable battery 36 V, 4 Ah

The third and fourth generation sensors have a time synchronization in the sub-microsecond range. Together with the mid device, sensor networks can be set up to localize of the AE sources. The mid device receives and saves the measurement data. In contrast to the configurations without localzation, the dynamic websites are not generated by the sensors but by the mid device.

The Mid Devise can be connected to five 4th generation sensors (one transmitter and four receivers) via Single Pair (SP) cables. This configuration forms an AE node. Several AE nodes that communicate with each other via WLAN can be mounted on the test object.

Advantages of the AE nodes:

Each generation 2 and 3 sensor was wirelessly connected to the mid device. This is associated with a high load on the heavily used ISM bands. In the new 4th generation, four receivers are connected to a Mid Device via SP cables. This typically reduces the amount of wireless data transmitted by a factor of 10 and increases the transmission speed by at least a factor of 4. The cables required are shorter than the distance between the transducers and easy to use because, in contrast to the Ethernet cables previously used, they only have one wire pair. The length of all cables is reduced by a factor of 10 compared to conventional AE systems with central signal processing.

Technical Specification Bosch GBA 36V 2Ah
Width x Length x Height
81 x 143 x 54 mm3
700 g
Typical uptime
400 h
Technical Specification GBA 36V 4Ah
Width x Length x Height
97 x 159 x 78 mm3
1400 g
Typical uptime
800 h
Technical Specification GBA 36V 6Ah
Width x Length x Height
116 x 180 x 89 mm3
1300 g
Typical uptime
1200 h
Technical Specification Bosch GBA 36V 9Ah
Width x Length x Height
114 x 170 x 95 mm3
2300 g
Typical uptime
3600 h
Technical Specification Mid Device G4.1
Sensor connections G4
1 transmitter, 4 receivers
Backward Compatibility
G2, G3
3 EFM32GG11
Mass Storage
Industrial Micro SD
Cellular network
IEEE 802.11b/g/n
IP Address
Fixed, Auto, DHCP
3 x LED   2 x Touch Button
Power Supply
DC 36 V
Power Consumption
< 800 mW
220 g
Width x Length x Height
92 x 126 x 27 mm3
Outer Casing
Protection Class
IP 20 or IP 54

Configuration example with 8 sensors:

Configuration with SP cables (green),sensors (blue) and mid devices (red)

The software contains location algorithms for different test objects. For every geometry there are programs that require the triggering of 3 or 4 transducers. At least 3 sensors are necessary for a plane localization. Error corrections are possible by adding a fourth transducer.

The above figure shows a square arrangement of the sensors. The dashed lines show two further basic variants of the location algorithms. The three red dashed squares correspond to the conventional algorithms. If the source is inside one of the squares, the four sensors at the corner points normally respond first. Inside the right and left squares, no information needs to be exchanged between the Mid Devices for localization. There is no load on the wireless connections. Inside the middle square, it is necessary for the information from two sensors to be transmitted wirelessly to the neighboring Mid Device. It is possible to completely avoid this if the localization is carried out using the two yellow dash-dotted squares. A Mid Device with its four sensors provides all the information for localization. The larger signal paths lead to a slight loss of sensitivity. Since the 4th generation also stores the measured values in a decentralized manner, the wireless connections are only used to operate the system and to display the results.