METHOD AND APPARATUS FOR DOWNLINK COMMUNICATION USING DYNAMIC THRESHOLD VALUES FOR DETECTING TRANSMITTED SIGNALS

摘要

The present invention provides a method and system in which signals from the surface are sent by changing flow rate of the drilling fluid supplied to the drill string during drilling of a wellbore. The signals are sent based on a fixed or dynamic time period schemes so that the sent signals cross a dynamic threshold value in a known manner. A controller downhole sets the dynamic threshold and determines the number of times a parameter, such as voltage, relating to the changes in the flow rate crosses the set dynamic threshold. Based on the number of the number of crossings and/or the number of crossings and the timing of such crossings, the controller ascertains the signal sent from the surface for use downhole.