| Abstract [eng] |
The objective of this research is to create a one sensor high resolution acoustic emission measurement system. To obtain this goal, two low noise and distortion amplifiers are designed, with gains of 46 dB and 60 dB. Gain could be reduced by 6 dB using relay switched voltage dividers. Amplified signal then goes to active low pass 7th order filter, unbalanced to balanced signal converter and finally to 16 bits analog to digital converter (ADC). Those circuits, together with six power supply regulators (three of them are used for ADC power supply), are layout on single printed circuit board (PCB), which consist of approximately 170 elements. In addition, another PCB is designed to reduce electromagnetic interference of field programmable gate array (FPGA) matrix. Board uses an optic decouples and differential line for the data transfer (to and from ADC) in order that noisy “ground” loops would not occur. Grounds between those boards are connected with capacitor. By using this technique, declared ADC dynamic range by manufacturer was reached (94 dB). Data from FPGA matrix is transferred to microcontroller, which writes it to SD memory card by using a file system (FAT). Recorded data is processed in computer. |
