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A reciprocating pulser system for generating pressure fluctuations in a flowing drilling fluid comprising a reciprocating poppet and a stationary valve assembly with axial flow passages. The poppet reciprocates in close proximity to the valve assembly, at least partially blocking the flow through th

A reciprocating pulser system for generating pressure fluctuations in a flowing drilling fluid comprising a reciprocating poppet and a stationary valve assembly with axial flow passages. The poppet reciprocates in close proximity to the valve assembly, at least partially blocking the flow through the valve assembly and generating oscillating pressure pulses. The poppet passes through two zero speed positions during each cycle, enabling rapid changes in signal phase, frequency, and/or amplitude thereby facilitating enhanced data encoding. The poppet is driven by a linear electric motor disposed in a lubricant filled housing. In one embodiment, the housing to shaft seal is a flexible bellows. In one embodiment, a force balance spring is used to essentially offset the hydraulic flow forces on the poppet. In one embodiment, a bypass poppet is used to adjust the differential pressure across the valve assembly.

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1. A reciprocating pulser system for generating pressure fluctuations in a flowing drilling fluid, comprising:a tool housing adapted to support a pulser assembly; the pulser assembly, comprising; a nozzle assembly disposed in the drilling fluid flow, said nozzle assembly having a main nozzle and at

1. A reciprocating pulser system for generating pressure fluctuations in a flowing drilling fluid, comprising:a tool housing adapted to support a pulser assembly; the pulser assembly, comprising; a nozzle assembly disposed in the drilling fluid flow, said nozzle assembly having a main nozzle and at least one bypass nozzle for channeling the drilling fluid flow through the nozzle assembly; a linear actuator assembly for driving a poppet in a first direction toward the main nozzle, and then in a reverse second direction away from the main nozzle, the poppet movement generating pressure fluctuations in the drilling fluid; and, an electronics module for controlling the pulser system. 2. The reciprocating pulser system of claim 1, wherein the tool housing is further adapted to house at least one upper pressure sensor proximate an upper housing end and at least one lower pressure sensor proximate a lower housing end.3. The reciprocating pulser system of claim 1, wherein the linear actuator assembly comprises;a lubricant filled actuator housing; a linear drive electric motor disposed in the lubricant filled housing, said drive motor adapted to drive the poppet in said first direction and said reverse second direction; a shaft with a first end adapted to attach to the drive motor, and a second end adapted to attach to the poppet; a force balance spring disposed between the drive motor and an actuator housing end cap, said spring designed to balance a drilling fluid force acting on the poppet; a seal for sealing between the housing end cap and the shaft, thereby preventing the intrusion of the drilling fluid into the lubricant filled housing. 4. The reciprocating pulser system of claim 3, wherein, the fluid seal for environmentally sealing between the housing and the shaft is a flexible elastomeric bellows.5. The reciprocating pulser system of claim 1 wherein the electronics module comprises circuitry to power and control the motion of the motor, and circuitry to power and read the pressure sensors.6. The reciprocating pulser system of claim 5 wherein the circuitry to control the motor comprises a programmable processor adapted to perform programmed instructions for controlling the motion of the motor.7. The reciprocating pulser system of claim 6 wherein the programmable processor is adapted to read pressure signals from the at least one upper pressure sensor and the at least one lower pressure sensor, said processor modifying the motor motion, according to programmed instructions, to maintain a predetermined differential pressure between the at least one upper pressure sensor and the at least one lower pressure sensor.8. The reciprocating pulser system of claim 5 wherein the programmable processor is adapted, according to programmed instructions, to detect and decode a command pressure pulse signal sent from a surface location, said processor thereby modifying the motion of the motor, according to programmed instructions.9. A method for generating a fast transition in a phase shift key encoding (PSK) scheme for mud pulse telemetry, comprising;utilizing a linear electric motor for driving a reciprocating poppet in a first direction and then in a reverse second direction to generate pressure pulses in a drilling fluid; driving the poppet with a first predetermined signal phase relationship; changing the drive signal according to the PSK scheme at a predetermined poppet position; and attaining a second predetermined phase relationship in no more than one poppet oscillatory period. 10. A method for generating a fast transition in a frequency shift key encoding (FSK) scheme for mud pulse telemetry, comprising;utilizing a linear electric motor for driving a reciprocating poppet in a first direction and then in a reverse second direction to generate pressure pulses in a drilling fluid; driving the poppet at a first frequency; changing the drive signal according to the FSK scheme at a predetermined poppet position; and attaining a second predetermined frequency in no more than one poppet oscillatory period. 11. A method for generating a fast transition in an amplitude shift key encoding (ASK) scheme for mud pulse telemetry, comprising;utilizing a linear electric motor for driving a reciprocating poppet in a first direction and then in a reverse second direction to generate pressure pulses in a drilling fluid; driving the poppet a first predetermined travel distance; changing the drive signal according to the ASK scheme at a predetermined poppet position; and attaining a second predetermined travel distance in no more than one poppet oscillatory period. 12. A method for generating an increased data rate in a mud pulse telemetry scheme by combining an amplitude shift key encoding (ASK) scheme and a frequency shift key encoding scheme (FSK), comprising;utilizing a linear electric motor for driving a reciprocating poppet in a first direction and then in a reverse second direction to generate pressure pulses in a drilling fluid; driving the poppet in a reciprocating motion through a first travel distance at a first frequency, thereby generating a first pulse amplitude at a first frequency; changing the drive signal according to the ASK and FSK schemes at a predetermined poppet position; and driving the poppet in a reciprocating motion through a second travel distance at a second frequency, thereby attaining a second pulse amplitude at a second frequency in no more than one poppet oscillatory period. 13. A method for generating an increased data rate in a mud pulse telemetry scheme by combining an amplitude shift key encoding (ASK) scheme and a phase shift key encoding scheme (PSK), comprising;utilizing a linear electric motor for driving a reciprocating poppet in a first direction and then in a reverse second direction to generate pressure pulses in a drilling fluid; driving the poppet in a reciprocating motion through a first travel distance at a fixed frequency at a first phase angle, thereby generating a first pulse amplitude at a first phase angle; changing the drive signal according to the ASK and PSK schemes at a predetermined poppet position; and driving the poppet in a reciprocating motion through a second travel distance at the fixed frequency at a second phase angle, thereby attaining a second pulse amplitude at a second phase angle in no more than one poppet oscillatory period.