Geosource, Inc.

Sperry-sun, Inc.

Wilson Industries, Inc.

Other

Amf Gmbh

Fairfield Industries, Inc.

Nl Sperry Sun, Inc.

Miles A Smither

Octavio A Vela

Harper E Sharp

James F Lockett

Elias H Codding

Edward M Browne

Franklin W Mayo

H Eugene Sharp

Jerry F Janecka

John D Jones

E Neil Shawhan

John W Linn, Iii

Emil S Macha

An apparatus to convert an input analog signal into a high resolution digital signal in a short conversion time. The device utilizes a high resolution feedback circuit to reduce the high clock generally necessary for high resolution analog-to-digital conversion. Such a device utilizes a low resolution analog-to-digital circuit, which is the only component that must operate at a high clock rate. The device amplifies the difference between the input signal and the feedback signal to obtain a first high resolution digital signal. The device further improves the resolution by combining a dither signal with the amplified difference between the feedback signal and the input digital signal to update the first high resolution digital signal. This updated digital signal is successively added in an accumulator to obtain a higher resolution digital signal.

High resolution analog-to-digital converter

An improved instantaneous floating point (IFP) amplifier is provided having a plurality of cascaded amplifier stages, with each stage having a plurality of possible gains. The input sample signal is passed through each stage so that no stage is selectively bypassed. A bipolar, logarithmic amplifier is used for gain control. The gain control bits correspond to the industry standard gain control codes, thereby eliminating the need for bit mapping. The offset voltage control circuit is initialized during power-up by removing the IFP input signal and measuring the input referred offset at each gain setting. The measurements are stored. When a sample signal is received at the IFP amplifier input, the appropriate gain is applied to that signal along with the stored offset value corresponding to that gain.

Instantaneous floating point amplifier

In a borehole telemetry system for acoustically transmitting data over a pipe suspended in a borehole, the level of noise in the data stream is inherently high due to the environment existing in a drilling operation and to the physical characteristics of a drill string. It has been discovered that certain discrete frequency passbands exist in a drill string which permit transmission of an acoustic signal with a minimum level of attenuation. In addition, it is now known that a fine structure exists within these frequency passbands which presents gaps or voids that attenuate the signal at a much higher rate. These gaps are on the order of 20 Hz. By generating an acoustic signal at a precise frequency spectrum within these passbands and then phase shifting the signal before its transmission, the energy spectrum of the transmitted signal is spread out over a sufficient frequency range to bridge these gaps.

Borehole acoustic telemetry system with phase shifted signal

The invention is a method and apparatus for substantially eliminating from a seismic signal channel an interfering hiline signal in a differential mode. Differential mode and common mode components of the interfering signal are coupled from the seismic signal channel, and are correlated with each other to obtain a correlation signal. The correlation signal and the common mode signal are multiplied to obtain a correction signal that is applied to the seismic signal channel to substantially eliminate the differential mode component of the hiline interference signal. The correlation between the differential mode and common mode signals is accomplished with both in-phase and quadrature phase components of one of them so that two correlation signals actually are produced.

Hiline interference eliminator

An improved duty cycle controlled filter, wherein a resistance is included in every circuit path that exists between a switch terminal and an amplifier terminal. Such improved filter produces low distortion and has been found to be especially useful in data acquisition circuits of seismic exploration systems.

Electronic filter

A transducer apparatus utilizing fiber optics for data transmission is disclosed in which an output optical signal is encoded with information representative of a parameter being measured and the encoded optical signal transmitted to a remote measurement and control apparatus site for decoding. The transducer is adapted to receive an input optical signal, and converts the input optical signal into electrical energy to power a driver. An electrical drive signal, generated by the driver, has a selectively variable frequency representative of the parameter being measured. Using the electrical drive signal, the output optical signal is generated. The driver includes a variable frequency oscillator whose frequency of oscillation is dependent upon the parameter being measured.

Transducer apparatus utilizing fiber optics for data transmission

A borehole survey instrument is provided having a meniscus type floating compass member with indicia thereon for indicating azimuth and inclination. A light source is disposed below the indicia for illuminating the indicia upward through the liquid through which the meniscus type floating compass member floats. A lens system is provided for focusing the image of the illuminated compass member upon a film disposed below the compass member. This arrangement permits the centering post for the compass member to be of minimum diameter consistent with rigidity requirements and permits a high angle compass member to indicate angles of inclination approaching ninety degrees. A multiple light bulb light source is utilized and each light bulb is mounted in a manner which permits a single light bulb to illuminate the entire compass member. A hand-held programming and diagnostic unit is provided which may be momentarily electrically mated with the borehole survey tool to input a programmed timed delay and diagnostically test both the condition of the light bulbs utilized as the illumination source and the state of the batteries within the instrument. This hand-held programmable unit eliminates all the mechanical programming switches and permits the instrument to be completely sealed from the pressure, fluids and contaminants normally found in a well bore.

Borehole survey instrument

A borehole survey instrument and control circuitry are described. The borehole survey instrument includes indicators for measuring angle of deviation from the vertical and angle of deviation from magnetic north and a photographic recording means for recording the output of the indicators at selected times. A lighting system is utilized in conjunction with the photographic recording means to expose photographic film and a novel time control circuit is utilized in conjunction with the lighting system to alter the length of time of illumination in accordance with the operativeness of individual bulbs within the lighting system. In this manner, the failure of one or more bulbs within the lighting system will not substantially affect the amount of illumination to which the film in the photographic recording means is exposed.

Borehole survey instrument control circuitry

Method and apparatus for determining the location of a break in a pair of wires of a multi-wire cable are disclosed. The method and apparatus permit such breaks to be found with a high degree of accuracy. The method and apparatus are especially useful in connection with locating breaks in seismic cables.

Cable break locator

An improved instantaneous floating point amplifier is provided having a plurality of cascaded amplifier stages, wherein the gain of a given stage of the amplifier is the square of the gain of the immediately succeeding stage of the amplifier. The number of amplifier stages which are required to implement the amplifier is minimized, and the control logic which is required to decide if a given stage is needed to amplify the input signal to a level within preselected limits is simplified. The amplifier has an automatic nulling feature which permits nulling of the amplifier without loss of data.

In a borehole telemetry system for acoustically transmitting data over a pipe suspended in a borehole, the level of noise in the data stream is inherently high, making the use of discrete frequencies advantageous to provide useful data. Any drift in electrical circuits which might affect or be affected by the use of precise frequencies is undesirable. A clock synchronization or bit rate clock circuit in a data signal processing system is operated by a local crystal oscillator which is operated at substantially the same precise frequency as a crystal oscillator that is used to generate and transmit the data signal. The synchronization of the bit rate clock is arranged to make only small corrections in order to keep the frequencies fully synchronized at all times thus false signals will not shift the clocks out of synchronization. The bit rate clock has an early late detector that determines if received data is expected early or late with respect to the data clock that is transmitting the data and shifts a window in the circuit accordingly. Another feature includes a fast search mode that causes the clock systems of the transmitted data signal and the clock system in the data signal processing circuit to move rapidly into synchronization when the signals are far out of synchronization, bypassing arrangements in the circuit that make only small corrections. The output of the bit rate clock operates a transmitter section to transmit the data signal at any desired frequency but at the same bit rate.

Borehole acoustic telemetry clock synchronization system

In a borehole telemetry system for acoustically transmitting data over a pipe suspended in a borehole, the level of noise in the data stream is inherently high, making the use of discrete frequencies advantageous to provide useful data. Any drift in electrical circuits which might affect or be affected by the use of precise frequencies is undesirable. A synchronous detector facilitates the removal of noise components from the data stream by comparing in a commutative filter the phase difference between a switching signal taken from the incoming data signal path, after the second stage of commutative filtering, with the data signal emerging from the last stage of filtering. The synchronous detector also compares a data signal having two stages of filtering with another data signal having six stages of filtering with the additional filtering, causing a phase shift in frequencies outside the precise frequency window, which the synchronous detector also rejects.

Borehole acoustic telemetry system synchronous detector

In a borehole telemetry system for acoustically transmitting data over a pipe suspended in a borehole, the level of noise encountered requires the use of specific frequencies to transmit data. Any drift in electrical circuits which might affect or be affected by such use of precise frequencies is undesirable. An automatic gain control (AGC) circuit is provided which obtains its feedback from a signal which has undergone some noise filtering so that the AGC circuit is controlled by a signal having a high signal-to-noise ratio. The circuit is arranged so that the wide temperature variations occurring in a downhole environment as well as component deterioration or change do not affect the frequency of the data signal or operation of the system in dealing with a precise frequency.

Borehole telemetry system automatic gain control

A sorting apparatus for sorting articles randomly disposed across a wide path is characterized by a plurality of side-by-side viewer elements each assigned a corresponding side-by-side sector of an illuminated viewed area through which the articles to be sorted pass. Electrical signals indicative of the instantaneous average value of light reflected from articles at two predetermined wavelengths as those articles pass through a sector of the viewed area are multiplexed and a classification signal functionally related to the ratio of the two signals is determined. The classification signal is compared to a reference signal indicative of an article having a predetermined physical characteristic, and a reject signal is generated if the compared signals differ by a predetermined amount. The reject signal is stored in an assigned memory location corresponding to the sector of the viewed area through which the article passed. At a predetermined later time, corresponding to the time necessary for an article to free-fall from the viewed area to the proximity of an ejector, the previously stored reject signal is read from memory and an ejector corresponding to the viewed sector through which article passed is actuated to remove the article from the article stream.

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Houston, TX, United States of America

Miles A Smither