Study and Implement of Downward Communication Function in Rotary Steerable Drilling System

In rotary steerable drilling system, there should be a downward communication channel to send the guided control command from ground monitor to downhole steeling tool. The downward command word has been transmitted by negative pulse of mud drilling fluid and encoded by a characteristic of three-descending and three-ascending. Downward communication receiving function in downhole tool detects the change of underground mud flow; then gets the guided control command rightly by processing and interpretation software. Several different measures are used in receiving device for improve reliability and anti-interference performance of downward transmitting. Experimental results show the feasibility of this downward transmission scheme.