Abstract: The system of the subject invention includes an antenna system, a surface apparatus and a battery-powered remote apparatus useful for applications such as well bore telemetry. In well bore telemetry, the surface apparatus is located uphole on the earth's surface and the remote apparatus is positioned at a remote location downhole in a well bore. The remote apparatus includes a sensor/transmitter unit for sensing physical characteristics such as pressure and/or temperature. The remote apparatus conserves power stored in its battery by transmitting change-in-pressure and/or change-in-temperature data that requires less power for transmission than absolute pressure and/or temperature data. The remote apparatus also conserves power by transmitting absolute pressure data in a single data frame and transmitting absolute temperature data in portions in a series of data frames.

Abstract: The methods of this invention reduce the amount of power consumed by a remotely positioned (i.e. downhole) sensor/transmitter used in applications such as well bore telemetry. The method involves the sensing of physical characteristics such as pressure and/or temperature to generate a first absolute value than is transmitted to a surface receiver located at the earth's surface. At a later time (or period) the physical characteristic is again sensed to generate a second absolute value that is subtracted from the first absolute value to generate a difference. If the difference is significant (i.e., greater than a predetermined value), the difference will be transmitted to the surface receiver. Because the difference will generally have fewer bits of data than the absolute data, less data can be transmitted so that battery power is conserved in the remote sensor/transmitter. In the event that the difference is not significant, even fewer bits need to be transmitted by the remote sensor/transmitter.