| 摘要 |
A method of determining amplitude and phase response of a receiver amplifier in an induction well logging instrument including the steps of generating an oscillating current at at least one frequency, energizing a transmitter coil instrument with the oscillating current, generating a first test signal having a known phase and amplitude relationship with respect to the oscillating current and a different frequen cy than any frequency in the oscillating current, amplifying and detecting voltages induced in a receiver coil corresponding to electrical properties of an earth formation, conducting a portion of the first test signal to the receiver amplifier causing the amplifier to generate a combined output including the first test signal and a signal resulting fro m the induced voltages, combining the oscillating current with the first test signal to fo rm a combined test/reference signal, spectrally analyzing the combined test/reference sign al and spectrally analyzing the combined output, and comparing spectral analysis of the combined test/reference to spectral analysis of the combined output to determine the phase and amplitude response of the receiver amplifier at the frequency of t he test signal. In a preferred embodiment, the method includes linear scaling of the respons e of the amplifier atthe test signal frequency to derive the amplifier response a t other frequencies in the voltages induced in the receiver coil corresponding to th e electrical properties of the earth formation.
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