| 摘要 |
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. Another method uses the fact that temperature is a more slowly changing phenomenon than pressure, and transmits data in frame formats constructed so that the transmission bit rate of sensed pressure data is higher than the transmission rate of sensed temperature data. In another method of this invention, the remote sensor/transmitter is programmed into a sleep state in which the remote sensor/transmitter consumes no appreciable battery power, for example, while being run down a well bore. The remote sensor/transmitter then transitions from the sleep state to the operation state after the expiration of a predetermined time period or by transmission of a control signal thereto.
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