.500 Msps, Sampling Real-time Data Acquisition And Dsp Applications, Design Research,

In the research work of this paper, real time sampling using alterable sampling frequency (the maximum was 500MSPS) was achieved. Digital signal was processed by DSP (Digital Signal Processor) and the processed data was sent to superior master machine to display via ISA bus.There was significant difference between the ultra-high-speed da-ta acquisition system and conventional medium-speed or low-speed sys-tem. Firstly, the sampling and transforming process of a system whose sampling frequency was over a certain level could hardly be control-led by software and general microcomputer interface, because general CPU couldn't provide adequate running speed. Secondly, alterability of sampling frequency was required in the work of this paper. The sy-stem had different requirements on time sequence in high-speed clock and low-speed clock situations, which resulted in the complexity of the sequential circuit. In such situation, controlling of the transf-orming process and synchronizing of sampled data only could be achie-ved via hardware, and data must be stored (by using high-speed stora-ge chip) and digital signal must be processed (by using high-speed D-SP) in real time simultaneously.In this paper, the whole design procedure was described detailed-ly, including comparison of schemes, selection of key chips, special usage of SBSRAM chip and circuit design based on the DSP chip. The D-SP chip used was the newest product of TI (TMS320VC5510). In order to experiment the application of bandpass sampling theory in digital o-scilloscope, multiple clocks of high quality were required, from whe-re the design of the main oscillation source with alterable frequency came into being. In order to increase the stability of the system, decrease the area of the PCB (printed circuit board) and reduce cons- umption of power, control logic were integrated into a single chip by using FPGA and CPLD. Since low-voltage chips were used, the voltage transform chip of LDO was used to transform the voltage.A system that was perfect in theoretical design sometimes could not obtain the expected performance in practice. Usually, it was bec-ause the effects of various actual exiting disturbances on circuit were not fully considered. Problems such as wiring of ground electrode, decoupling of power source and reflection of signal transmission li-ne etc were not effectively solved. Besides, effects on other electr-onic devices must be considered. The EMC (Electro Magnetic Compatibi-lity) and the design of PCB were also involved in these problems. Si-nce above problems were still unsolved in the design of high-speed d-igital system, to study the interference-free design technique of hi-gh-speed digital system was of great necessity.