Patent ID: 7245229

Claim:
A method for communicating with a downhole device deployed in a subterranean borehole, the method comprising: (a) deploying a downhole device in a subterranean borehole, the device being coupled to a drill string, the drill string being rotatable about a longitudinal axis, the device including a measurement device operative to measure rotation rates of the drill string about the longitudinal axis; (b) predefining an encoding language comprising codes understandable to the downhole device, the codes represented in said language as predefined value combinations of drill string rotation variables, said variables including a difference between first and second rotation rates; (c) causing the drill string to rotate at substantially a preselected first rotation rate; (d) causing the drill string to rotate at substantially a preselected second rotation rate; (e) causing the measurement device to measure the first and second rotation rates; and (f) processing downhole the difference between the first and second rotation rates measured in (e) to determine if one of said variables is received and acquiring at least one code from the variable at the downhole device, wherein the difference is not based on a preselected base rotation rate.