Switched Integrator Preamplifier And Embedded Network Data Acquisition System

Industrial Computerized Tomography (ICT) is regarded as the best nondestructive testing (NDT) technique and has been widely used in the inspection of critical design applications in the field of industry, such as aviation, spaceflight and so on. ICT achieves its prominence as a result of high density resolution and three-dimensional imaging. With the increasing precision demanding on the quality of imaging, more and more new techniques have been applied to the design of ICT. This paper describes the application of a dual-mode switched integrator preamplifier and embedded network data acquisition system in the design of ICT system. Switched integrator preamplifier operated in pulse current integrator mode or continuous current mode correspond to the high energy X-ray radiation from an accelerator and the low energy X-ray radiation from an X-ray generator respectively. Compared with the conventional resistor-capacitor feedback preamplifiers, the switched integrator preamplifier get better noise performance due to removing the contribution of the noise associated with the feedback resistor. Switched integrator preamplifier also avoid the ballistic deficit, undershoot and pile-up of signal pulses which will appear in the resistor-capacitor feedback preamplifiers due to the fact that the equivalent resistance of the switch is so large when it is off that the decay of the preamplifier pulse is long enough to be considered infinite, and when the switch is on, the equivalent resistance is so small that the charges are released quickly from the feedback capacitor. By configuring the integration capacitor and time, the switched integrator preamplifier could make the equivalent feedback resistance even larger than hundreds of to amplify the micro current from the detectors just as a transconductance amplifier does, which must rely on the use of extremely large resistors. In the present paper, the noise character of the switched integrator preamplifier is discussed. We also simulate the noise performance of the preamplifier with and without the Gaussian pulse shaping using PSpice and make an experiment on it.The embedded network data acquisition system based on the RCM3200 module satisfies the ICT's demanding for data acquisition, reliable and fast transmission. The system integrates 8-bit Rabbit3000 MCU, AX88796 Ethernet controller, RAM and other necessary components to realize the data transmission on network through TCP/IP stack. The present paper implements the data transmission based on TCP and UDP respectively, and gets nearly 400KB/S data rate with TCP and nearly 600KB/S data rate with UDP. Considering comprehensively the demanding for reliable and fast data transmission, we believe the UDP is the appropriate choice, and the software module used for assuring the reliability of data transmission is necessary.