分布式多通道电法电磁法数据同步采集系统

Distributed multi-channel data acquisition system for electrical and electromagnetic methods

采集系统是电磁法仪器的重要组成部分,设计出高精度、低功耗的分布式采集系统是电磁法仪器研制的重点和难点.本文设计的采集系统集成了6个采集通道,每个采集通道的A/D转换器都选用了32位的ADS1282,并通过DAC1282来提供ADS1282校准和自检所需要的外部信号.采集部分的控制中心选用了MachXO2 ZE系列这款功耗极低的CPLD.为了保证同步采集的精度,设计中采用了GPS和OCXO协同授时的方案来提供同步时钟.采集系统具备MT、CSEM、SIP等测量功能.测试结果表明,本采集系统同步精度维持在1E-11以下,待机状态下功耗为0.32 W,运行功耗2.76 W,各通道短路噪声值均在μV级,信噪比在118 dB附近,满足设计要求.

The data acquisition system is an important part of the electromagnetic instrument.Designing a high-precision,low-power distributed data acquisition system is a key and difficult point in the development of electromagnetic instruments.The data acquisition system designed in this paper integrates six data acquisition channels.The ADS1282 is selected for each acquisition channel’s A/D converter,and external signals required for ADS1282 calibration and self-test are provided by DAC1282.The control center of the acquisition system uses the MachXO2 ZE series,a very low power CPLD.In order to ensure the accuracy of the synchronous acquisition,a GPS and OCXO cooperative timing scheme is adopted in the design to provide a synchronized clock.The acquisition system has measurement functions such as MT,CSEM,and SIP.The test results show that the synchronization accuracy of the acquisition system is maintained below 1 E-11.The power consumption is 0.32 W in standby mode,and 2.76 W in the operating state.The short circuit noise value of each channel in the level ofμV,and the signal-to-noise ratio is near 118 dB.In summary,this system meets the design requirements.