一种微电阻率成像测井仪数字相敏检波新算法

A Novel Digital Phase-Sensitive Detection Algorithm of Micro-Resistivity Imaging Logging Tool

针对微电阻率成像测井仪井下稳定、高效及低功耗设计要求,提出了一种较新颖的数字相敏检波实现算法,主要包括数据的分相累加、公因式乘法、匹配加法以及反正切与平方根运算等。其中,分相累加算法在采集模块FPGA中完成,公因式乘法和匹配加法在处理模块FPGA中完成,反正切和平方根运算在处理模块DSP中完成。通过此种相敏检波算法实现方式,能有效降低系统功耗,并实现地层阻抗的准确测量。

Aiming at the design requirements of stability,efficiency and low-power of down-hole for micro-resistivity imaging logging tool,a novel digital phase-sensitive detection algorithm is proposed.The method mainly includes dividing phase accumulation,common factor multiplication,matching addition,arctangent and square root calculations,etc.Among them,the dividing phase accumulation is accomplished in the acquisition module FPGA,the common factor multiplication and the matching addition are accomplished in the processing module FPGA and the arctangent and square root calculations are accomplished in the processing module DSP.By phase-sensitive detection method,system power consumption can be effectively reduced and accurate measurement of formation impedance can be achieved at the same time.