US Patent 8689884 Mud pulse telemetry system

A mud pulser tool to be positioned into a downhole environment is disclosed. The mud pulser tool includes a control valve that is selectively opened to allow fluid to flow through the mud pulser tool or selectively closed to restrict the fluid flow, wherein the control valve is selectively opened or closed to produce a mud pulse signal transmitted through the fluid. The mud pulser tool also includes a sensor system to measure a pressure drop across the control valve. In one example, the mud pulser tool includes a control system to selectively open or close the control valve to adjust the pressure drop to produce a selected pressure drop across the control valve.