Apparatuses and systems for reducing power consumption in remote sensing applications

• US 5,784,004 A
• Filed: 06/20/1995
• Issued: 07/21/1998
• Est. Priority Date: 12/13/1994
• Status: Expired due to Fees

• Current Assignee: Gas Technology Institute (GTI Energy)
• Original Assignee: Gas Research Institute (GTI Energy)
• Inventors: Toellner, Robert L., Esfahani, Farhad, Davis, James Lloyd
• Primary Examiner(s): ELDRED, JOHN W
• Application Number:
  US08/492,814
• Time in Patent Office: 1,127 Days
• Field of Search: 340/854.6, 340/855.5, 340/856.3, 340/588, 340/589, 340/870.17, 340/870.16, 340/853.6, 340/870.05, 340/853.9, 340/853.5, 73/152.02, 175/40, 175/45, 175/50, 166/250
• US Class Current: 340/854.6
• CPC Class Codes: E21B 47/06 Measuring temperature or pressure
• CPC Class Codes: E21B 47/07 Temperature
• CPC Class Codes: E21B 47/13 by electromagnetic energy, e.g. radio frequency
• CPC Class Codes: G01V 3/34 Transmitting data to recording or processing apparatus; Recording data

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. The remote apparatus can transition between initial time delay, fixed transmit sequence, sleep, operation, and test states based on its control program and/or based upon the transmission of control data from the surface apparatus. The surface apparatus receives a main signal from the remote apparatus and a reference signal from the antenna system and uses the reference signal to remove noise components from the main signal.

Claims

1. An apparatus comprising:

a temperature sensor generating a sensed temperature signal;

a pressure sensor generating a sensed pressure signal;

a controller coupled to receive the sensed temperature signal from said temperature sensor and the sensed pressure signal from said pressure sensor, storing previous pressure and temperature data, determining change-in-pressure data based on the sensed pressure signal and the previous pressure data, determining change-in-temperature data based on the sensed temperature signal and the previous temperature data, generating extrapolated pressure data based on the previous pressure data, generating extrapolated temperature data based on the previous temperature data, determining the change-in-pressure data based on the sensed pressure signal and the extrapolated pressure data, determining the change-in-temperature data based on the sensed temperature signal and the extrapolated temperature data, generating frame data including at least one of the change-in-pressure data and the change-in-temperature data, generating a transmitter activation signal after the frame data is generated, and generating a control signal to modulate a carrier signal based on the frame data;

a wake-up delay counter coupled to said controller, generating a count checked by said controller to determine an expiration of a sleep state, said controller controlling said apparatus to enter an operation state if the count is greater than or equal to a predetermined value;

a wave generator generating the carrier signal;

a modulator coupled to said wave generator, to modulate the carrier signal based on the frame data;

a transmitter coupled to said modulator and said controller, said transmitter being activated based on the transmitter activation signal if said apparatus is in the operation state, to amplify the modulated carrier signal; and

an antenna coupled to said transmitter, to generate an electromagnetic transmission signal based on the amplified, modulated carrier signal from said transmitter.

2. An apparatus as claimed in claim 1, wherein said modulator includes a phase shifter for differentially phase shift keying (DPSK) the carrier signal based on the frame data, to generate the modulated carrier signal.

3. An apparatus as claimed in claim 1, wherein the extrapolated pressure data is determined by linear extrapolation from the previous pressure data, and wherein the extrapolated temperature data is determined by linear extrapolation from the previous temperature data.

4. An apparatus as claimed in claim 1, further comprising:

a first multiplier coupled to receive a reception signal from the antenna and a sine wave having a frequency of the carrier signal, from said wave generator;

a second multiplier coupled to receive the reception signal from the antenna and a cosine wave having the frequency of the carrier signal, from said wave generator;

a first voltage-to-frequency converter coupled to said first multiplier and said wave generator, generating a first frequency-converted signal based on a high-frequency signal from said wave generator and the sine wave;

a second voltage-to-frequency converter coupled to said second multiplier and said wave generator, generating a second frequency-converted signal based on the high-frequency signal from said wave generator and the cosine wave;

a first counter coupled to said first voltage-to-frequency converter and said controller, generating a first count based on the first frequency-converted signal; and

a second counter coupled to said second voltage-to-frequency converter and said controller, generating a second count based on the second frequency-converted signal;

said controller determining that a "1" or "0" bit has been transmitted based on the first and second counts.

5. An apparatus as claimed in claim 4, further comprising:

a switch unit coupled between said antenna and said first and second multipliers, and coupled to said controller, the switch unit being controlled by the controller to selectively switch between a transmission mode in which said antenna is decoupled from said first and second multipliers, and a reception mode in which said antenna is coupled to said first and second multipliers.

6. An apparatus as claimed in claim 4, wherein said modulator includes a phase shifter for differentially phase shift keying (DPSK) the carrier signal based on the frame data, to generate the modulated carrier signal.