基于串行总线的井下多通道高速高精度数据采集系统的设计

Design of high-speed and high-precision data acqusition system with multi-channel applied to downhole tools on the basis of serial bus

设计了一种八通道高速高精度并行数据采集系统。该系统具有14位分辨率,4×105次/s最高转换速度。采用复杂可编程逻辑器件(CPLD)实现了数据采集速率和采集数据量的程控选择功能,并控制FIFO缓存波形数据。数字处理器(DSP)通过串行命令总线控制采集速率、采集深度并启动采集;通过串行高速数据总线读取采集数据并进行实时处理。整个电路控制灵活,指标先进,结构紧凑,适合高性能井下设备使用。井下测试结果表明,波形特征明显,信噪比高。

a kind of high-speed and high-precision parallel data acqusition system with 8 channels was designed. The system is characterized by a resolution ratio of 14 digits and the highest conversion speed of 4 × 10^5 s^-1. The program-controlled selections of data acquisition speed and amount are available by use of complex programmable logical device （CPLD）, which controls the first-in-first-out memory buffer waveform data. Data acquisition speed, acquisition amount and starting of wave acquisition are all controlled by digital signal processor （DSP） through serial command bus. Acquisition data are read through high-speed serial data bus and then are processed in real time. The whole circuit has the advantages of flexible control, advanced target, compact structure and suitable for high performance downhole tools. The results show that the signal to noise ratio（SNR） and the characteristics of the measured waves are good.