| 摘要 |
<P>PROBLEM TO BE SOLVED: To solve the problem that, in an electromagnetic induction type buried object exploration apparatus employing a digital signal processor (DSP), sufficient sensitivity can not be obtained because of a limitation in quantization level or the like during digitization, and it is difficult to detect an optical fiber cable accommodated in a non-metal channel, through any simple indirect approach. <P>SOLUTION: A crystal active filter has a center frequency adjustment function and a crystal resonator break protection function, a filter of ultra narrow band and high DU ratio can be easily configured by multi-stage connection, and a high-sensitivity electromagnetic induction type buried object exploration apparatus can be accomplished. Thus, an optical fiber cable accommodated in a non-metal pipe can be detected through a simple indirect approach. <P>COPYRIGHT: (C)2012,JPO&INPIT |
