Patent ID: 6600995
Filing Date: 2003-07-29
Classification: G01V

Abstract:
An apparatus for measuring the resistivity of an earth formation penetrated by a borehole comprising:a waveform generator comprising a memory device containing digital samples of a transmitted waveform representing at least one periodic waveform having a frequency; a clock signal and memory locations to access successive samples; a digital-to analog converter to generate a time-varying, periodic voltage proportional to said samples in said memory; at least one transmitter that is energized by said time-varying, periodic voltage; at least one set of receivers generating a receiver voltage; an analog-to-digital converter that periodically samples the receiver voltage at a predetermined sampling rate and outputs a digitized voltage signal; a processor that receives the digitized voltage signal; and a set of N accumulators that collates and averages successive sets of N samples from the analog-to-digital converters to output a set of N averages where N has a predetermined value that satisfies the Nyquist criterion for said frequency.