Design of an USB-based Synchronous Data-acquisition System with Sampling-rate Programmable

摘要

The sampling-rate of most Data-acquisition system is generally constant which constrains the efficiency of using data buffer, because the adjustability of data recording time is not well for a fixed magnitude of data buffer when the frequency of several kinds of tested signals varies in a large range. In order to meet the need of data-acquisition and processing in testing and measuring several kinds of radar signals, an USB-based dual-channel data-acquisition system, which has a programmable data-sampling speed, is introduced on this paper. The sampling-speed of each channel is programmable and varies from 200Ksps to 40Msps, and the data buffer is 32KB. When frequency of tested signals varies from 20KHz to 10MHz, the data recording time can be adjusted dynamically from 0.8ms to 320ms and the magnitude of wave is from 8 to 6500, which in some extent resolves the contradictions between sampling-speed and data recording time. The hardware of the system is composed of a MAX1424-based Data-Analog circuit, a CY7C4265-based high speed and programmable FIFO buffer circuit, a programmable synchronous sampling-clock circuit and a CY7C68013-based USB interface and control circuit, etc. In terms of the software of this system, C++builder programming environment is used to realize the human-computer interface and LabWindows/CVI the dynamic-linked library of general data processing.