Data Acquisition And High Resolution Frequency Spectral Analysis System Based On USB2.0

During the modern industry manufacture and science research, the requirement of data acquisition and frequency spectrum analysis is increasingly brought up. The previously data acquisition system is mostly based on PCI or ISA bus, which has many disadvantages. However, the USB2.0 technique has many merits, such as plug and play, simple installation, anti-electromagnetic interference, resistant limit of computer slots. Moreover, the previously frequency spectrum analysis methods were mostly based on FFT, so the resolution was very low because of the limited observe datum. They were gradually replaced by modern spectral power estimated methods. Therefore, it is significant to do some research on data acquisition and high resolution spectral analysis system.According to the requirement of vibrating signal detection, this paper designs a multi-channel data acquisition system, which has a programmable signal amplifier, variable sample rate and sample time. This system can sample signal on different channels simultaneously and the highest sample rate of one channel is 400ksps. The data acquisition system has many advantages, such as simple structure, low cost, high reliability.During the hardware design section, this paper introduces the theory of data transfer based on USB2.0 protocol and the whole hardware design scheme. After that, this paper deeply analyses the conversion sequence of A/D device AD7899 and the principle of the hardware design which uses two methods to complete the data transfer between the interface of GPIF and the asynchronous FIFO storage.During the software design section, the thoughts of the software program are explained from four aspects. Firstly, in order to corporate with peripherylogic circuit and realize high date transfer rate, firmware is completed. Secondly, this paper discusses the device driver programs. Thirdly, DLL is completed to facilitate users to further develop. Fourthly, the spectral analyses software is designed.In the end, this paper introduces the shortages of classical power spectral estimate methods, and then improves the modern power spectral estimate methods to increase spectral resolution. In order to substantiate this system can sample signal veraciously and feasibly, this system was tested by the already known signal.