基于DDS三分量感应测井信号源系统设计

Design of 3D explore signal generator based on DDS technology

介绍了直接数字频率合成(DDS)的原理,依据其基本原理设计一款基于PIC单片机控制的DDS信号源,单片机通过SPI总线方式接收来自上位机发来的频率信号,将其存入EEPROM中,并转换为40位频率控制字写入DDS芯片中使其输出所需频率信号。DDS输出的频率信号含有大量杂散信号,经过7阶椭圆滤波器滤除杂散信号得到纯净的频率信号,再经功率放大后输出至后一级大功率放大电路。实验表明该信号源输出频率范围在1Hz～1MHz,准确度可达0.01Hz,满足三分量感应测井的要求。

It introduces the principle of DDS and gives a kind of 3D explore signal generator design,which based on DDS controlling by PIC microchip.The PIC can receive the frequency data from the host computer via SPI bus and save to EEPROM.After it converts frequency data into 40-bit serial-load word and write into the DDS chip,the needed frequency signal which contains a lot of spurious signals will be produce by DDS chip.Thought a 7th Elliptic filter a pure frequency signal can be obtained.Then,it will be amplified to the last circuit.Test report says that this design can produce 1Hz to 1MHz frequency by the accuracy of 0.01Hz and meets the 3D explores requirements.