Parallel Sampling Technology Research For High Precision Sensors

With the development of science and technology, and wide application of the data acquisition system, higher requirements of the data acquisition system's speed and accuracy are advanced. In the field of precision sensors, data acquisition systems are required not only a high sampling precision to achieve nanometer measurement accuracy, but also a higher sampling rate to increase the input bandwidth. Therefore, to design a rapid and high precision data acquisition system is particularly important.After researching a great deal of the existing A/D converters, I find that the single-chip A/D is difficult to achieve both high speed and high precision sampling. In another word, the speed and accuracy is always a pair of contradictions. Parallel time interleaving is a very viable option for improving system performance and speed at the same time.Based on the needs of high-precision sensors, the crucial techniques concerning high precision and high speed data acquisition system are discussed and researched. Based on parallel time-interleaved sampling technology, the implementation scheme of system is advanced and verified, and the design of hardware and software is accomplished. The experimental results show that this program can greatly improve the performance of data acquisition system. The main research is given as follows:Firstly, according to the expectant target of the subject, the subject develop four 24-bit A/D converters parallel time-interleaved sampling technology program, to use four high-precision, low-speed A/D for the purpose of high-precision, high sampling rate.Secondly, there are a large number of data from data acquisition needing to a wide variety of computing and deal with, so TI company's C6000 series TMS320D642 is used.Thirdly, in order to improve the efficiency of the DSP, using the CPLD to complete the whole system of logic control, timing adjustment, provide the input and output interfaces. Realize the USB bus communication circuit design and firmware programming between this system and the host computer.Finally, a series of experiment is carried out to verify system's performance indicators. A large number of experiments show that this system has 0.1mV resolution, 7.8ksps sampling rate of low-frequency signal measurement.