| Nowadays, most of the DAQ(Data Acquisition) systems used in accelerator andnuclear physics areas are based on CAMAC, FASTBUS, VME or PXI structure. Thesesystems are specially built for large medium-sized physical experiment terminals likeBEPCIII or ATLAS. Due to the system’s complexity and high cost, these DAQ systemsneed really special care and maintenance, so they cannot be easily pushed to otherapplications. But in the accelerator beam diagnostics, small physics experiments anddetector calibration measurements, small, portable, multi-parameter DAQ system can befully adequate. Based on these reasons, we developed a kind of small, both easy to carryand extend multi-parameter DAQ system.The DAQ system has the following advantages:1. A self-designed bus system is used in this DAQ system. Its max data transmissionspeed is33MB/s which can meet the need of the DAQ system working in cascade mode.2. The SROM communication logical is used as the communication method betweenARM and FPGA. Its speed, which is66.5MB/s, can meet the requirements of the datatransmission from FPGA to ARM.3. The DAQ system is designed as a portable device, and it can be used to measuremultiple parameters at the same time.4. A DAQ software, with proprietary intellectual property rights, is developed for theDAQ system. This dissertation mainly describes the detail procedures of the design for theportable DAQ(PDAQ) system including the design of the peak detect and hold circuit,the design of the flexible bus, the communication method between the FPGA and theARM, the design of the PDAQ software and the data processing. The main content of thisdissertation is summarized as follows.The first chapter focuses on the background of the DAQ systems. It introduces themain DAQ systems used in nuclear physics laboratories. And then it shows the keyproblems that we must solve in the design of the PDAQ system.The second chapter focuses on the design of the hardware parts for the PDAQsystem. Firstly, it introduces the architecture of the PDAQ system. Secondly, it describesthe hardware design for the communication between the FPGA and the ARM. And then,it shows the disadvantages of the old peak detect and hold circuit, and provides a newcircuit for this PDAQ system. At last, it introduces the bus design of the system.The third chapter focuses on the logic design of the PDAQ system. The FPGA isused to coordinate the working of the circuits in the system. And many clock signals withdifferent frequencies are used in different function modules. So we must synchronizesignals from different clock systems, or the system will be unstable and the metastablestate will happen. In order to solve these problems, this chapter introduces many methodsof signal synchronization and clock unifying. Finally, this chapter describes the logicdesign of the bus and the communication method design between the FPGA and the ARM,which are the most important parts in the system.The forth chapter focuses on the design of the software for the PDAQ system. Thereis an embedded computer (ARM) in the PDAQ system. And the computer runs Linuxoperation system. So we must design the driver program and server program for the ARM.Besides that, the PDAQ software, running in the backend computer, is needed for datatransmission, processing and storage. In order to ensure the correctness and reliability of the data transmission, a frame and a data storage structure are designed for the system.The fifth chapter focuses on the processing of the nuclear experiment data. Itintroduces the methods for the background eradication, the noise filtering, the spectrumsmoothing, the gold deconvolution, the peak searching and the peak area calculate.The sixth chapter focuses on the test and verification. It introduces the test of thelinear and the precision for the system. And then it introduces a real nuclear experiment,which is measuring the energy spectrum of the Na22, comparing with the CAMACmodule PHILLIPHS7164.The seventh chapter is the summary and the outlook. |
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