Abstract: A method of acoustically transmitting data signals is presented. In accordance with the present invention, the optimum transmission frequencies for transmitting and receiving acoustic data signals are determined by use of at least two spaced acoustic transmitter/receiver pairs located at or near opposed ends of the drillstring. Using the method of this invention, one acoustic transmitter will transmit at different frequencies while transmitted signal characteristics are monitored by the acoustic receiver at the other end of the drillstring. As a result, the optimum frequencies are determined for that particular drillstring geometry. This adaptive procedure allows the downhole acoustic transmitter to transmit uphole to the uphole acoustic receiver at the identified optimum frequencies. This adaptive method of optimizing transmission frequencies is continued as segments of drill pipe are added and other drillstring parameters change.

Abstract: An exercise aid, worn on the head as a sweatband or built into a helmet or hat, which enhances exercise benefits while minimizing exercise interruptions or distractions. A microcomputer processes heart rate, time and exercise-related inputs and records selected information. A speech synthesizer provides voice output to inform and give instructions to the wearer. Easily located and actuated controls allow convenient operation while actively exercising. Through an interface to an external computer, the device may be programmed to provide the wearer with a customized sequence of instructions and information may be read out for analysis.