一种随钻方位电磁波测井仪发射电路设计

Design of transmitting circuit for azimuth wave propagation logging tool while drilling

随钻方位电磁波仪器常见为多频、多组天线设计,仪器通过分时发射不同频率的电磁波信号并接收回波,根据回波信号的幅值和相位信息来推算地层信息。在仪器工作过程中,电磁波发射电路是仪器关键的组成部分,直接影响仪器性能。基于数字频率直接合成技术设计了一种随钻方位电磁波仪器发射电路,发射出的正弦波信号频率、相位、幅度均可通过改变程序来控制调整,具有输出信号频率、相位分辨率高、幅度易调整、信号稳定、功耗低等特点。详细介绍了发射电路中DDS信号产生电路、滤波电路、数模调幅电路、功率驱动电路等重要组成部分,经试验结果证明该设计方案可行,能够满足随钻方位电磁波仪器功能需求。

The azimuth wave propagation logging tool while drilling is usually designed with multi-frequency and multi-group antennas,it transmits electromagnetic wave signals of different frequencies by time-sharing and receives the return wave,and it calculates formation information according to the amplitude and phase information of the return wave.In the working process of the tool,the electromagnetic wave transmitting circuit is a key component of the tool,which directly affects the performance of the tool.Based on the technology of digital frequency direct synthesis,a transmitting circuit for azimuth wave propagation logging tool is designed,and the frequency,phase and amplitude of the output signal can be controlled and adjusted by changing the program,which has the characteristics of high resolution of frequency and phase,easy adjustment of amplitude,stable signal and low power consumption.This paper introduces the DDS signal generating circuit,filtering circuit,digital amplitude modulation circuit,power driving circuit and other important parts of the transmitting circuit.The test results show that the design scheme is feasible and meets the functional requirements of azimuth wave propagation logging tool while drilling.