Sperry-sun, Inc.

Nl Sperry Sun, Inc.

Elbert N Shawhan

Data is transmitted through a drill string by means of acoustical energy by transmitting an acoustical signal for a first predetermined interval and ceasing transmission of the signal for a second predetermined interval to represent a first binary state; ceasing transmission of the signal for a third predetermined interval to represent a second binary state; and combining transmission and cessation of transmission of the signal in binary sequences representative of borehole data.

Data transmission in a drill string

Binary bits that are represented by pulses are identified by circuitry that integrates a signal having a sequence of such pulses for the period of each bit pulse. At the end of the integrating period, the integrator level is stored, and the integrator is discharged. Storage and discharge are synchronized with the bit pulse rate by an oscillator whose frequency is varied until the integrator level is maximized. The presence of a bona fide signal bit is indicated by a predetermined integrator level. A false signal bit generated as part of the background noise will not endure long enough to cause the integrator to reach the predetermined level of a bona fide bit.

Bit identification system for borehole acoustical telemetry system

A lock-in filter that may be used to detect an AC data signal in the presence of high level noise signals that may occur in such systems as those used for acoustical telemetry in boreholes includes a pair of parallel capacitors receptive of the data and noise signals and circuitry operating in response to signals in the capacitors for alternately switching the capacitors to receive the noise and data signals in phase with the data signal.

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West Chester, PA, United States of America

Elbert N Shawhan