Abstract: A pressure pulse generator, or "pulser," and methods for operation are described. The pulser is constructed of a stator and rotor mounted within a housing, each being configured with a central hub and one or more radially extending lobes. An equal number of ports are spaced between the lobes. The lobes of the rotor are cross-sectionally tapered in the streamwise direction. The rotor and stator are maintained within the housing in a coaxial spaced relation from each other. The axial distance between the rotor and stator may be selectively varied by a linear actuator. In a preferred embodiment, the linear actuator comprises a conventional solenoid assembly which is operably associated with the rotor to move it axially within the housing with respect to the stator between a first position, wherein the distance between the rotor and stator is reduced, and a second position, wherein the distance between the rotor and stator is increased. The linear actuator is energized in response to signals from an encoder.