Communications: electrical – Wellbore telemetering or control – Diagnostic monitoring or detecting operation of...
Reexamination Certificate
1995-05-01
2001-08-07
Christensen, Andrew B. (Department: 2612)
Communications: electrical
Wellbore telemetering or control
Diagnostic monitoring or detecting operation of...
C340S853800, C340S854800, C340S870310, C340S010330
Reexamination Certificate
active
06271767
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to the field of subsurface ocean data telemetry and in particular to a system utilizing a standard surface buoy mooring line as the transmission medium.
2. Description of the Prior Art
At the present time most in situ deep ocean data collected over any length of time are stored on magnetic tape or other recording medium in a subsurface instrument, and are not available until the instrument is recovered. However, the current availability of inexpensive satellite telemetry has prompted interest in developing a technique to permit near real time telemetering of oceanographic data from the deep ocean to the laboratory.
Solar powered radio transceivers mounted on surface ocean buoys are presently in use. These transceivers send telemetry data to satellite receivers and are useful for collecting ocean surface and weather information. Systems capable of sending subsurface oceanographic data to satellites over relatively long periods of time, however, are not known to be available. One problem with subsurface instruments is finding reliable means for the transfer of data between the instruments and a surface transceiver.
It has been proposed that the inductive properties of the cable on which subsurface instruments are suspended be used to transmit collected oceanographic data. Such a system is disclosed in U.S. Pat. No. 3,314,009 to Murdock in which an electrically insulated cable with a conductive core is lowered into the ocean by a ship. Multiple instruments are clamped onto the cable, which inductively transfer data into the cable. A receiver on the ship connected to the cable receives and records the information.
What is needed is a system which addresses the needs of in situ subsurface data collection utilizing existing buoy mooring lines and radio transmitters and receivers and which permits reliable transfer of oceanographic data for extended periods without the requirement of frequent battery replacement.
SUMMARY OF THE INVENTION
The preceding and other shortcomings of the prior art are addressed and overcome by the present invention which transmits data over standard mooring lines between a master and one or more slave modems and has a low power sleep mode to reduce power consumption when data is not being transferred.
In one aspect the invention provides an inductive modem telemetry instrument for measuring oceanographic data for use with an electrically insulated conductive cable immersed in seawater including a master modem inductively coupled to the cable, one or more transducers responsive to the characteristics measurable in seawater, slave modem means inductively coupling signals from the transducers through the cable to the master modem, and means for reducing power consumption of the instrument when signals are not being coupled from transducers to the master modem.
In another aspect, the invention provides an inductive modem telemetry system including an electrically insulated cable having a conductive core, the cable constructed to be immersed in seawater, an instrument removably attached to the cable at a preselected location for disposition in the seawater, a transducer in the sensor responsive to conditions in the seawater to generate electrical signals related thereto, a slave modem in the sensor interconnected with the transducer to generate modem encoded signals dependent upon the characteristics of signals received from the transducer, an inductive coupler in the sensor enveloping the cable and interconnected with the sending slave modem, the inductive coupler constructed to induce electrical signals in the center conductor of the cable in accordance with signals received from the slave modem, means for reducing power consumption of the transducer, slave modem and inductive coupler when signals are not being induced into the center conductor of the cable by the inductive coupler, and a master modem inductively coupled to the slave modem via the cable at one end portion using the seawater as a return path to receive signals from the slave modems via the cable.
In yet another aspect, the invention provides an inductive modem telemetry system including an electrically insulated cable having a conductive core, the cable constructed to be immersed in seawater, a sensor removably attached to the cable at a preselected location for disposition in the seawater, a transducer in the sensor responsive to the characteristics of the seawater to generate an electrical signal related to data to be collected, a slave modem in the sensor interconnected with the transducer to generate modem encoded signals dependent upon the data from the transducer, an inductive coupler in the sensor enveloping the cable and interconnected with the slave modem, the inductive coupler constructed to induce electrical signals in the center conductor of the cable in accordance with signals received from the slave modem and to receive signals in the center conductor, means for reducing power consumption of the transducer, slave modem and inductive coupler when signals are not being induced into the center conductor of the cable by the inductive coupler, and a master modem inductively coupled with the cable at one end portion thereof, using a seawater return path, to receive signals from and send signals to the slave modems by way of the cable.
These and other features and advantages of this invention will become further apparent from the detailed description that follows, which is accompanied by several drawing figures. In the figures and description, numerals indicate the various features of the invention, like numerals referring to like features throughout both the drawings and the description.
REFERENCES:
patent: 3314009 (1967-04-01), Murdock
patent: 4713967 (1987-12-01), Overs et al.
patent: 4794575 (1988-12-01), Miller
patent: 4817044 (1989-03-01), Ogren
patent: 4924698 (1990-05-01), Echert et al.
patent: 4953986 (1990-09-01), Olson
patent: 5083457 (1992-01-01), Schultz
patent: 5095308 (1992-03-01), Hewitt
patent: 5200743 (1993-04-01), St Martin et al.
patent: 5686902 (1997-11-01), Reis et al.
patent: 1280321A (1986-12-01), None
D. E. Frye and B. Owens, “Recent Developments In Ocean Data Telemetry”, Proceedings of the IEEE Fourth Working Conference on Current Measurement, Apr. 3-5, 1990, published Aug. 1990.
Brown Neil
Doherty Kenneth
Fougere Alan
Frye Daniel
Christensen Andrew B.
Irell & Manella LLP
Woods Hole Oceanographic Institution
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