发明名称 |
Apparatus for measuring resistivity of an earth formation using delta-sigma digital signal generation and sigma-delta digital detection system |
摘要 |
An apparatus for measuring resistivity of an earth formation. The apparatus includes at least one source of measuring current. The source includes a delta-sigma modulator and a serial bit source coupled to the modulator. The serial bit source represents the magnitude of the measuring current at spaced apart time intervals. The apparatus includes a sensor responsive to formation current resulting from interaction of the measure current with the earth formation. The sensor is coupled to a sigma-delta modulator. The modulator is coupled to a digital mixer and a digital filter. The output of the digital filter corresponds to the magnitude of the measure current detected by the sensor sampled at spaced apart time intervals. In a preferred embodiment, the apparatus includes a plurality of current sources each having a different frequency. The sigma-delta modulator is coupled to a plurality of mixers each for demodulating one of the different source frequencies.
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申请公布号 |
US5585727(A) |
申请公布日期 |
1996.12.17 |
申请号 |
US19950373409 |
申请日期 |
1995.01.17 |
申请人 |
WESTERN ATLAS INTERNATIONAL, INC. |
发明人 |
FANINI, OTTO N.;FABRIS, ANTONIO |
分类号 |
G01V3/24;(IPC1-7):G01V3/10 |
主分类号 |
G01V3/24 |
代理机构 |
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主权项 |
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地址 |
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