In some embodiments, an apparatus and a system, as well as a method and an article, may operate to transmit and receive data. Transmission may comprise transforming larger values of acquired data into smaller values of transformed data using a transform defined by a seed value selected to reduce digital pulse position modulation transmission time for the acquired data. Additional activities include digital pulse position modulating the transformed data and a checksum associated with the transformed data to provide a propagation signal, and transmitting the propagation signal into drilling fluid or a geological formation. Reception may comprise receiving the propagation signal, demodulating the propagation signal to extract the transformed data and the checksum, and transforming the transformed data into an estimate of the acquired data, using the transform defined by the seed value validated by the checksum. Additional apparatus, systems, and methods are described.

Systems and methods for digital signal processing are provided. A method includes mapping a symbol in a pulse sequence by using a pulse width and a pulse start in the symbol, reading a message using a symbol value for each symbol in a string of symbols, and modifying a drilling configuration according to the message. A device configured to perform the above method is also provided.

The invention relates to a wellbore-lining tubing comprising at least one window pre-formed in the wall of the tubing and a device for selectively generating a fluid pressure pulse, and to a method of forming a lateral wellbore employing such a tubing. In an embodiment, a wellbore-lining tubing (130m) is disclosed which comprises: a tubing wall (32m), an internal fluid flow passage (30m), and at least one window (154m) pre-formed in the wall of the tubing; a device (34m) for selectively generating a fluid pressure pulse, the device located at least partly in a space (36m) provided in the wall of the tubing; and a coupling (190) for receiving a deflection tool (192) so that the deflection tool can be secured to the tubing and employed to divert a downhole component (202) through the window in the tubing wall.

A method for selecting a drilling fluid pressure pulse transmission frequency in a downhole telemetry tool comprises: emitting a frequency sweep wave in a drilling fluid that comprises pressure pulses over a range of frequencies and over a period of time; measuring a pressure of the drilling fluid at the telemetry tool while the frequency sweep wave is being emitted; determining a signal strength at each frequency in the range of frequencies from the measured pressure of the drilling fluid; and selecting at least one frequency in the range of frequencies that meets a selected signal strength threshold as a telemetry signal transmission frequency for the telemetry tool. The method can further comprise encoding the at least one selected frequency in a header message and transmitting the header message to surface using pressure pulse telemetry, and then encoding telemetry data into a pressure pulse telemetry signal and transmitting the pressure pulse telemetry signal to surface at the at least one selected frequency.

A smart lower end system that can detect multiple events and failures during the generation of pressure pulses by a pulser is disclosed. Pulser failures may occur if the pilot valve fails to fully close or open, if the signal shaft fails to move and close pilot valve orifice, or if movement of the pilot valve or signal shaft is restricted. The components of the smart lower end system may cycle between sleep and wake states to allow for low power operation.

A fluid pressure pulse generator for a downhole telemetry tool comprising a stator and a rotor. The stator comprises a stator flow diverter radially extending across a flow path for fluid flowing through the fluid pressure pulse generator and having one or more than one stator flow channel therethrough through which the fluid flows. The rotor comprises a rotor flow diverter radially extending across the flow path for fluid flowing through the fluid pressure pulse generator and having one or more than one rotor flow channel therethrough through which the fluid flows. The rotor flow diverter is axially adjacent the stator flow diverter and the rotor flow diverter is rotatable relative to the stator flow diverter to move the one or more than one rotor flow channel in and out of fluid communication with the one or more than one stator flow channel to create fluid pressure pulses in the fluid flowing through the fluid pressure pulse generator. A rotor/driveshaft coupling releasably couples the driveshaft of a probe of the tool and the rotor such that the probe can be decoupled from the rotor and removed from a sub housing the fluid pressure pulse generator.

In accordance with some embodiments of the present disclosure, systems and methods for a toolface control system is disclosed. The system includes, a rotating drill string of a drilling tool, an assembly located within the rotating drill string representing a current toolface of the drilling tool, and a controller configured to use pulse width modulation to adjust a rotational speed of the assembly to maintain the current toolface at a desired toolface.

Method and apparatus for generating fluid pulses in a fluid column, such as within a downhole well, are disclosed. A described example fluid pulse generator utilizes a moveable flow conduit through which at least a portion of a downwardly flowing fluid column will pass. The moveable flow conduit can be moved, such as by pivoting, in and out of registry with other components defining the fluid flow path to provide resistance to flow of a selected duration and pattern, and thereby to generate pressure pulses within the fluid column detectable at the surface. In some examples, magnetic actuators will be used to perform the described pivoting of the moveable flow conduit.

A system for fluidic siren based telemetry is provided. The system includes a non-rotating restrictor and a rotating restrictor positioned relative to the non-rotating restrictor that is configured to control a flow passage to the non-rotating restrictor. The system includes a turbine coupled to the rotating restrictor and configured to rotate in response to fluid flow along a flow path. The system also includes a generator coupled to the turbine and a controller device electrically coupled to the generator. The controller device is configured to provide one or more encoded signals to the generator to adjust a rotational velocity of the rotating restrictor and causing the rotating restrictor to create different acoustic signatures through the flow passage for wireless communication of a telemetry signal to a surface based on the adjusted rotational velocity of the rotating restrictor.

A telemetry system includes a downhole device configured to generate modulated pressure pulses in drilling fluid within a drill string, first and second transducers configured provide first and second telemetry signals, respectively, responsive to pressure variations in the drilling fluid, and a telemetry computer coupled to the transducers. The telemetry computer includes a processor and a memory coupled to the processor. The memory contains instructions that, when executed by the processor, cause the telemetry computer to be configured to transform the first and second telemetry signals to a time-frequency domain representation to provide first and second time-frequency telemetry signals, respectively; and apply an unmixing filter to the first and second time-frequency telemetry signals to provide an enhanced signal in the time-frequency domain. The enhanced signal has a source signal component separated from a noise component, and the first and second telemetry signals are mixed source-noise signals.