Data processing: measuring – calibrating – or testing – Measurement system in a specific environment – Earth science
Reexamination Certificate
1999-11-05
2001-12-18
McElheny, Jr., Donald E. (Department: 2862)
Data processing: measuring, calibrating, or testing
Measurement system in a specific environment
Earth science
C324S357000
Reexamination Certificate
active
06332109
ABSTRACT:
The present invention relates to a data acquisition system and in particular to a geological data acquisition system.
The invention has been developed primarily for geophysical surveys utilising controlled sources and natural sources for identifying metalliferous regions within a geological body, and will be described herein after with reference to that application. However, it will be appreciated that the invention is not limited to this particular field of use and is also applicable to other geological, geotechnical or environmental surveys.
The purpose of exploration geophysics is to produce images of sub-surface physical properties. The value of the images produced and manifested is dictated by the available spatial resolution and the property accuracy at all points. While this information can also be used to surmise or interpret chemistry and rock type, this is of secondary importance since such interpretations will be limited to the accuracy of the physical property image.
Owing to fundamental physical principles of linearity and reciprocity, the quality of the images produced by the available geophysical imaging systems is dictated by
1. the multiplicity of source/receiver combinations or field/field response sites;
2. the combination of linearity and instantaneous dynamic range of the measurements (which are limited by a wide range of noise considerations some of which do not directly relate to system design);
3. the bandwidth in the measurements (also limited by various noise considerations in addition to basic system design); and
4. one or more indicators related to the degree of confidence in the accuracy of the images (estimates of sensitivity and error).
While such limitations are valid for all available prior art systems, there are additional problems compromising their ability to take useful measurements and therefore produce valuable images. More particularly, the prior art systems:
1. are custom made and configured for one particular type of electrical geophysical technique;
2. generally employ a single type of sensor; and
3. rely upon field operation techniques that were developed over twenty years ago.
These compromises have resulted in the proponents of the prior art systems trying to glean ever diminishing amounts of information from data sets of marginal quality. Moreover, although some improvements to equipment has been made, it is only incremental. The state of the art remains constrained to 30 year old designs and methodologies.
Some of these limitations have been recognised in the seismic exploration industry, where use is made of distributed acquisition systems and 3-D surveys. However, seismic surveys involve measuring motion or pressure only and the hardware techniques are not translatable to electrical geophysics. The latter employs a much wider range of sensors that are several orders of magnitude more demanding in terms of bandwidth, and also more demanding in terms of linearity and dynamic range.
It is an object of the present invention, at least in the preferred embodiment, to overcome or ameliorate at least one of the deficiencies of the prior art.
According to a first aspect of the invention there is provided a data acquisition system for obtaining data from a geological body, the system including:
a plurality of nodes for simultaneously obtaining respective first measurement signals representative of predetermined characteristics of the body at a corresponding plurality of spaced apart locations at or adjacent to the surface of the body;
first memory means disposed at each node for selectively storing first data representative of the first measurement signals; and
a processing centre remote from the nodes for selectively obtaining the first data from the memory means.
Preferably, the first signals are obtained at a first predetermined time and the nodes also obtain respective second measurement signals at a second predetermined time, wherein the first and second times are temporally spaced. Preferably also, the memory means stores second data representative of the second signals. Even more preferably, the fist data and the second data allow a determination of the first time and the second time.
Preferably also, the body is provided with an actuating signal and the system includes an input sensor means for obtaining an input signal representative of one or more characteristics of the actuating signal at the first time and the second time. More preferably, the input means includes second memory means for storing input data representative of the input signal. More preferably, the processing centre selectively obtains the second data from the second memory means. Even more preferably, the processing centre is responsive to the first and the second data for calculating geological or geophysical parameters of the body.
In a preferred form the nodes are linked to the processing centre sequentially. More preferably, each node is connected to the or each adjacent node in series, and one of the nodes is connected in series to one adjacent node and to the processing centre. More preferably the connections between the nodes is effected by electrical cabling. In other embodiments, however, alternative means such as optical cables or radio frequency or other wireless links are used.
Preferably, the processing centre provides control signals to the nodes and the input sensor means for coordinating the simultaneous acquisition of the measurement signals and the input signals. More preferably, the control signals actively compensate for transmission delays between the nodes. Even more preferably, the control signal actively compensate for transmission delays between the processing centre and the one or more adjacent nodes and between the transmission centre and the input means.
According to a second aspect of the invention there is a method for obtaining data from a geological body, the method including the steps of:
simultaneously obtaining with a plurality of nodes respective first measurement signals representative of predetermined characteristics of the body at a corresponding plurality of spaced apart locations at or adjacent to the surface of the body;
selectively storing first data representative of the first measurement signals in first memory means disposed at each node; and
locating a processing centre remote from the nodes for selectively obtaining the first data from the memory means.
Preferably, the method includes the additional steps of:
obtaining the first signals at a first predetermined time; and
obtaining with the nodes respective second measurement signals at a second predetermined time, wherein the first and the second times are temporally spaced.
Preferably also, the method includes the step of storing second data representative of the second signals in the memory means. Even more preferably, the first data and the second data allow a determination the first time and the second time.
Preferably also, the method includes the steps of:
providing the body with an actuating signal; and
obtaining with an input sensor means an input signal representative of one or more characteristics of the actuating signal at the first time and the second time.
More preferably, the method includes the step of providing the input means with second memory means for storing input data representative of the input signal. More preferably, the method includes the step of the processing centre selectively obtaining the second data from the second memory means. Even more preferably, the processing centre is responsive to the first and the second data for calculating geological or geophysical parameters of the body.
In a preferred form the nodes are linked to the processing centre sequentially. More preferably, each node is connected to the or each adjacent node in series, and one of the nodes is connected in series to one adjacent node and to the processing centre. More preferably the connections between the nodes is effected by electrical cabling.
Preferably, the processing centre provides control signals to the nodes and the input senor means for coordinating t
Ritchie Terry John
Sheard Stuart Nicholas
Kenyon & Kenyon
McElheny Jr. Donald E.
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