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2. 发明专利

JPS56166481A DECIDING METHOD OF EARTHQUAKE 失效
公开(公告)号：JPS56166481A
公开(公告)日：1981-12-21
申请号：JP7002080
申请日：1980-05-28
申请人： FUJITSU LTD
发明人： KAKEHI HAJIME , HOSHINO KEIYUU , TAKIZAWA HIROSHI , KOUNO YOSHIAKI , HACHITANI ATSUAKI
IPC分类号： G01V1/00 , G01V1/30
摘要： PURPOSE:To enable a proper trigger decision to be performed even when the ground noise is nonstationary, by connecting a variable gain amplifying circuit to the stage previous to a filter circuit. CONSTITUTION:The digital input signal sent from an earthquake telemeter is supplied to a filter circuit 3 from an input terminal 1 through a variable gain amplifying circuit 2 in order to pass only the component to be observed, which is supplied to an absolute value circuit 4. The signal therefrom is supplied to a short-time movement averaging circuit 6, where a movement average value by a short-time sampling is obtained. Said signal is supplied also to a long-time movement averaging circuit 5 through a switching circuit 51, where a movement average value by a long-time sampling is obtained. The latter, which is obtained only when there is no earthquake through the circuit 51 which is closed then, is an average ground noise, which is multiplied by alpha in a multiplier circuit 71 and compared with the former to decide an earthquake. In addition, the latter is compared with a set value 81 in order to control the gain of the variable gain amplifying circuit 2 so that the average ground noise is slightly higher than the noise level resulting from the arithmetic error.

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