Abstract: A video system having a transmitter in which a composite signal is formed by combining digital information with scanlines of an analog video signal generated by a line scanning device, and a receiver in which the digital information is recovered. The digital information is combined with the analog video signal at predetermined locations along scanlines of the video signal, and these predetermined locations are varied in order to prevent visible deterioration of the video image. In the video receiver, the digital information is recovered by examining the composite signal at the predetermined locations to extract the digital information. Each bit of digital information to be conveyed is represented by a first pseudo-random digital pulse sequence (or its complement, depending on whether the data bit is 1 or 0) which is superimposed on a selected scanline of the analog video signal to form the composite signal.

Abstract: In a multi-device data transmission system with source and acceptor devices linked by a data highway and handshake lines, provision is made for automatically adjusting the delay of the handshake cycle to suit the highway length and other determinative factors. This is achieved in that the acceptors do not accept data until told so to do via one handshake line, whereas the source is only allowed to issue this command when it has been told via another handshake line that all acceptors have seen the data. The system determines its own delay in this way and automatically adapts the delay to whatever length of highway is employed, whether a fraction of a meter in a circuit board or several tens of meters in inter-rack wiring.

Abstract: An assembly adapted to be anchored at a subsurface location within a tubular well conduit to function as a self-closing safety valve. The assembly includes a flapper valve closure element pivotably mounted in a tubular valve housing and controlled by a pressure sensitive control mechanism. An anchoring means having radially expansible anchoring and sealing members is employed to secure the valve in place and to form a seal which forces fluid in the conduit to flow through a flow passage in the valve housing. The expansible anchoring and sealing means may be retracted to permit retrieval of the entire assembly. The control mechanism includes a pressure charged bellows chamber which moves in response to a drop in the pressure within the well conduit to cause the flapper to close the flow passage.An incompressible fluid contained within the bellows of the control mechanism cooperates with a double acting valve to prevent over extension or over compression of the bellows by extremes in pressure differential.

Abstract: In accordance with an illustrative embodiment of the present invention, a subsurface safety valve assembly that automatically closes in response to a drop in flowing pressure at the valve to a value that is below a set dome pressure, is provided with a flow restriction upstream of the valve that is sized to enable rapid closing of the safety valve in the event of disruption of surface flow lines or the like.

Abstract: A measuring device such as a digital thermometer uses dual slope analog-to-digital converter techniques but elminates the usual need for a high precision voltage source. An input capacitor is connected through novel switching to the temperature responsive arm and the temperature insensitive arm of a resistance bridge, to the low precision voltage source and to the output of the integrator and detector amplifiers. The switching sequence is such that long term changes in the voltage source and in the amplifier offset and drift are cancelled out during measurement cycles, thereby providing highly accurate measurements without the usual need for an expensive high precision voltage source.

Abstract: In a DVOM of the dual slope type, an unknown resistance or conductance to be measured is connected to a reference signal source to generate a voltage or current which is measured by the DVOM. However, if the input impedance of the DVOM is not extremely high, it loads the unknown resistance or conductance, and renders the relationship between the value of the unknown resistance or conductance and the actual voltage or current measured by the DVOM non-linear. In order to correct for this, a proportion of this actual voltage or current is algebraically summed with the reference signal used in the DVOM for generating the second slope of its dual slope operation, the proportion being selected in dependence on the input impedance of the DVOM (which can thus now take any convenient value) to linearize the relationship between the value of the unknown resistance or conductance and the output signal of the DVOM.

Abstract: A bipolar reference voltage source comprises first and second ratio-matched transistors having respective collector load resistors and arranged to pass slightly different currents. The emitter of the first transistor is connected to two emitter resistors in series, while the emitter of the second is connected to the junction between the emitter resistors. The bases of the transistors are commoned, while their collectors are respectively connected to the two inputs of a differential amplifier. A switching arrangement has a first state in which the output of the differential amplifier is connected to the bases of the transistors, and the end of the two emitter resistors remote from the transistors is grounded, thereby producing a first reference voltage of one polarity at the output of the differential amplifier.

Abstract: In accordance with an illustrative embodiment of the present invention, a method and apparatus for logging an earth formation of interest is disclosed in which repetitive bursts of a continuous energy spectrum of photons are emitted that penetrate the media surrounding a borehole traversing the earth formation. Thereafter, indications of photons resulting from the interaction of the emitted photons and the surrounding media are obtained, each indication begin obtained at a different separation from the source along the axis of the borehole. Finally, the indications are compared to determine representations of a characteristic of the media surrounding the borehole. According to one aspect of the present invention, at least one of the indications is the result of annihilation photons produced by the interaction of the emitted photons and the surrounding media.

Abstract: A spectrum analyzer including a device for analyzing signals whose time duration is short as compared to the normal sampling rate of the spectrum analyzer. A transient signal, or a small portion of any analog signal, is sampled at a sampling rate which is substantially higher than the normal sampling rate of the spectrum analyzer, and the samples are stored in analog form in a storage device such as a charge coupled device acting as an analog delay line. The stores analog samples are then read out at the normal sampling rate of the spectrum analyzer, to form a longer duration signal which can be analyzed by the spectrum analyzer in a conventional manner.

Abstract: A control valve apparatus adapted to be positioned within a subsea blowout preventer stack for controlling the flow of fluid from an offshore well includes a control unit releasably latched to a valve body having tandem, normally closed valve assemblies, the upper valve assembly including a flapper valve element and the lower valve assembly including a ball valve element. The control unit has hydraulically operable mechanisms adapted to open the valve elements in response to pressurization of control lines extending upwardly to the surface, and to assist in closure of the ball valve element to effect cutting of wireline or cable extending into the well in case of emergency.

Abstract: In the representative embodiment of the present invention disclosed herein, this new and improved perforating apparatus includes a unique elongated carrier strip of a ductile steel carrying encapsulated shaped explosive charges having their forward ends fitted and snugly secured against the concave rear face of the strip by means of externally-threaded axial projections respectively threaded into tapped charge-mounting holes closely spaced along the carrier. The forward face of the carrier strip and the rear portions of the capsules are complementally shaped for accommodation within a given size of well bore piping thereby allowing the largest-possible mass of explosive to be disposed in each capsule.

Abstract: Apparatus for repairing insulation of an insulated conductor comprising a split yoke; an elongate, substantially cylindrical cavity formed in the mating surfaces of the yoke; an elongate, split, substantially cylindrical conductor mold or insert removably positioned in the cavity; an injection molding unit communicating with an opening in the conductor insert through an injection bore in the yoke to inject insulator into the conductor mold through such bore; a heating element within the yoke to melt the injected insulator over an area comprising the central area of the conductor mold; and a cooling element within the yoke to cool the ends of the conductor mold while the central area is heated, whereby the heat applied to the insulated conductor within the conductor mold does not extend to insulated conductor outside the yoke. In an optional embodiment, a tensioning device can be used to maintain the insulated conductor under tension during the repair.

Abstract: Disclosed is a pumping system using a pneumatically powered, submerged pump for lifting high viscosity oil from a well. The pump includes a flexible, bag-shaped expansible member or "bladder" mounted within a surrounding housing. Pressurized gas is supplied from the well surface to the bladder through a supply line. An inlet check valve permits oil in the formation to flow into the housing when the bladder is collapsed. When the bladder is expanded or displaced by the gas, the oil in the housing is displaced through an outlet check valve into a flow line which extends to the well surface. A submerged control valve channels gas into the bladder to control the bladder expansion. The control valve also functions to permit the gas in the bladder to flow into a vent tube to control bladder deflation.In a modified form of the invention, oil flowing into the housing expands the bladder and gas supplied to the housing collapses the bladder.

Abstract: In accordance with an illustrative embodiment of the present invention as disclosed herein, a shock absorber adapted to be incorporated in a drill string includes axially splined housing and mandrel members having a helical coil spring reacting therebetween to absorb longitudinal vibration and shock loads and otherwise attenuate exciting forces generated by the drill bit. The coil spring has a low spring rate and is enclosed between the housing and a hollow flow tube that is slidably sealed with respect to the housing and the mandrel.

Abstract: Apparatus for presetting an electric pulse counter to a given count without any action on its parallel input terminals and/or its parallel output terminals. The apparatus comprises a pulse generator which is connected, during a preset operation, to the count input of the counter through an electronic gate. The electronic gate is controlled by an auxiliary circuit. In one embodiment, the auxiliary circuit comprises as many voltage comparators as flip-flops in the counter. The voltage comparators enable the electronic gate as long as the states of the flip-flops are different from the desired states. In another embodiment, the auxiliary circuit mainly comprises a divider by N, N being the desired count. In a first step, the divider is reset and the counter is caused to count up to its maximum count and to deliver an overflow pulse when it resets. In a second step starting with the overflow pulse, both counter and divider count up from zero and the electronic gate is closed when the divider reaches the N-count.

Abstract: A symmetrical non-linear network for use in a function generator in which one or other of a pair of transistors is brought progressively into conduction by a non-linear network, so as to present a low dynamic resistance between the terminals. The non-linear network preferably includes a pair of diodes having a lower turn on voltage than that of the associated transistors, for example Schottky diodes with silicon transistors.The invention also provides a function generator incorporating the above non-linear network for converting square waves to sine waves in which the amplitude of the input signal to the network is controlled automatically.

Abstract: A dual slope analog-to-digital converter, which has an autozeroing circuit for cancelling out integrator and detector offset and drift, is additionally provided with a circuit for injecting a voltage of selected polarity and magnitude to offset the input voltage of the converter such that the input voltage can be measured with respect to a nonzero reference line.

Abstract: A control valve apparatus adapted to be stationed in a subsea blowout preventer stack and used in connection with a production or drill stem test of an offshore well from a floating vessel, includes a valve section and a control section that are releasably connected together by a latch mechanism. The valve section has one or more fail-close valves for controlling the opening of the well, and the control section and latch mechanism are hydraulically operable for respectively actuating the valves and disconnecting the control section to enable its retrieval to the vessel leaving the valve section in place.

Abstract: In the several representative embodiments of the new and improved methods disclosed herein, a cable-suspended spinner-type flowmeter is successively lowered and raised at selected speeds in a well bore containing one or more flowing fluids whose velocity or flow rate are to be determined. In one manner of practicing the invention, the flowmeter is passed back and forth through a lower static well bore interval for establishing the response of the tool at zero flow rates. In this way the output measurements obtained from the runs through the higher or dynamic intervals can be uniquely correlated for accurately determining the velocity and flow rate of the well bore fluids in each dynamic interval independently of differences in fluid viscosity.

Abstract: In an analogue to digital converter the unknown voltage is applied continuously to an integrating circuit during each conversion period. An opposing reference voltage is switched on and off to cause the amplifier output to ramp up and down between two detection levels. One or both of these levels varies as a periodic function of time, e.g. a sawtooth waveform. Clock pulses are counted when the slope of the output ramp is of one sign only and it is shown that the ratio of the unknown voltage to the reference voltage is simply related to the number of clock pulses actually counted when the slope is of said one sign and the total number of clock pulses occurring during the conversion period.