Electromagnetic Technique of Measuring Coal Layer Thickness

Ellerbruch, D.A.; Belsher, D R.

doi:10.1109/tge.1978.294575

Cited by 16 publications

(15 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Ellerbruch and Belsher [7] developed an FM-CW GPR to measure coal layer thickness. They achieved reasonable results although the desired accuracy was not achieved to warrant further research [8].…”

Section: Introductionmentioning

confidence: 99%

Near-surface Interface Detection for Coal Mining Applications using Bispectral Features and GPR

Strange

Ralston

Chandran

2005

Subsurf Sens Technol Appl

View full text Add to dashboard Cite

The use of ground penetrating radar (GPR) for detecting the presence of near-surface interfaces is a scenario of special interest to the underground coal mining industry. The problem is difficult to solve in practice because the radar echo from the near-surface interface is often dominated by unwanted components such as antenna crosstalk and ringing, ground-bounce effects, clutter, and severe attenuation. These nuisance components are also highly sensitive to subtle variations in ground conditions, rendering the application of standard signal pre-processing techniques such as background subtraction largely ineffective in the unsupervised case. As a solution to this detection problem, we develop a novel pattern recognition-based algorithm which utilizes a neural network to classify features derived from the bispectrum of 1D early time radar data. The binary classifier is used to decide between two key cases, namely whether an interface is within, for example, 5 cm of the surface or not. This go/no-go detection capability is highly valuable for underground coal mining operations, such as longwall mining, where the need to leave a remnant coal section is essential for geological stability. The classifier was trained and tested using real GPR data with ground truth measurements. The real data was acquired from a testbed with coalclay, coal-shale and shale-clay interfaces, which represents a test mine site. We show that, unlike traditional second order correlation based methods such as matched filtering which can fail even in known conditions, the new method reliably allows the detection of interfaces using GPR to be applied in the near-surface region. In this work, we are not addressing the problem of depth estimation, rather confining ourselves to detecting an interface within a particular depth range. KEY WORDSGPR, bispectrum, interface detection, horizon control, coal mining.

show abstract

Section: Introductionmentioning

confidence: 99%

Near-surface Interface Detection for Coal Mining Applications using Bispectral Features and GPR

Strange

Ralston

Chandran

2005

Subsurf Sens Technol Appl

View full text Add to dashboard Cite

show abstract

“…A portable (toboggan mounted) radar system, typically called an FM-CW system, was developed to measure and record profiles of snow-packs down to ground level and to monitor changes in snow stratigraphy as a function of time of day. Details of the system operation are reported elsewhere (Ellerbruch and Belsher, 1978). The system was continuously swept in frequency over the bandwidth 8-12 GHz.…”

Section: Introductionmentioning

confidence: 99%

Snow Stratigraphy and Water Equivalence Measured With an Active Microwave System

Ellerbruch

Boyne

1980

J. Glaciol.

View full text Add to dashboard Cite

This paper reports on research on the relationship between the electromagnetic scattering properties and physical properties of snow-pack. An FM-CW active microwave radar system operating in the frequency range 8-12 GHz is used to scatter electromagnetic radiation from surface and subsurface stratigraphic layers in the snow-pack. The amplitude of the scattered radiation as a function of depth in the snow-pack can be correlated with such physical characteristics as density, hardness, stratigraphy, and moisture content. A direct determination of snow-pack water equivalence can be made from these observations.

show abstract

“…489434) was the first to propose the use of a pulsed radar to detect and measure the depths to buried dielectric interfaces. [Cook, 1975;Ellerbruch & Belsher, 1978;Coon, Fowler & Schafers, 1980;Roe & Wittmann, 1982;Pittman et al, 1984;Yelf & Turner, 1990] (see Section 2.2), to detect pipes and cables [Caldecott et al, 1988], and some military work including tunnel detection and non-metallic mine detection [Iizuka & Freundorfer, 1983]. In 1988, Daniels, Gunton & Scott, 1988 published their highly cited tutorial paper entitled "Introduction to subsurface radar" , which comprehensively reviewed the history, applications and techniques of GPR at that time.…”

Section: Historical Development Of Gprmentioning

confidence: 99%

“…This task becomes increasingly more difficult over shorter periods. For example, a faster STC can increase the gain of the receiver by 30 dB in 10 ns [ Wright, Bradley & Grover, 1994], [Ellerbruch & Adams, 1974], Using a 1-2 GHz FMCW radar design, the roof thickness of a layer of coal (up to 55 centimetres) was measured in three US underground coal mines [Ellerbruch & Belsher, 1978]. Further experimental work continued with this system until 1982, when it was decided that further efforts to ward improving this FMCW GPR system were not worthwhile [Roe & Wittmann, 1982], This decision was based on the fact that an alternative technique for de termining the thickness of coal by measuring the intensity of the natural gamma background radiation from shales was acceptable for the application.…”

Section: Impulse Gprmentioning

confidence: 99%

“…The Southwest Re search Institute (SwRI) built a 2-6 GHz FMCW GPR system capable of determining coal thicknesses up to 1.25 inches, with a resolution better than a quarter of an inch [SwRI, 1978]. A separate FMCW system was proposed around the same time by the US National Bureau of Standards [Ellerbruch & Adams, 1974], and a system operat ing between 1-2 GHz was built and tested in an experimental underground coal mine [Ellerbruch & Belsher, 1978]. Following on from this work, another FMCW system…”

Section: Cook 1970 Measured the Re Electrical Properties Of Coal Anmentioning

confidence: 99%

See 1 more Smart Citation

Stepped-frequency radar design and signal processing enhances ground penetrating radar performance

Noon¹

View full text Add to dashboard Cite

This thesis presents a theoretical analysis and applied evaluation of the steppedfrequency radar technique and shows that significant performance benefits can be achieved in ground penetrating radar (GPR) applications. These benefits are suc cessfully demonstrated in field trials of a newly designed stepped-frequency GPR system.An original contribution has been made in establishing a unified characterisation of the performance of GPR for constant Q materials. This enables the maximum penetration depth of a GPR system to be characterised as a fixed number of wave lengths which is constant for any frequency. Similarly, the resolution is expressed as a fixed number of wavelengths which is also constant with frequency. These expressions prove to be a useful design tool in characterising GPR performance in dependently of frequency, and in selecting the waveform parameters for a defined application.A rigorous theoretical study of the stepped-frequency radar technique is un dertaken, which demonstrates the "synthesis" of an impulse waveform using an IDFT-based matched filter with minimum-phase. It is concluded that a physically realisable stepped-frequency radar has far-reaching benefits in the form of higher processed mean energy than an impulse radar with the same frequency bandwidth.A 1-2 GHz stepped-frequency GPR prototype has been completely designed and built to test the above theories. The primary application for this system design is the high-resolution mapping of thin coal seam structures in open-cut coal mines.The 1-2 GHz frequency band is selected to meet the performance requirements of one metre penetration and five centimetre resolution in coal.A novel technique is presented which corrects the broadband quadrature receiver errors in the stepped-frequency radar prototype. It is shown that the technique suppresses the Hermit,Ian images by more than 50 dB below the target responses.The external loop gain of the system is measured to be 156 =b 6 dB for bow-tie antennas and 166 dz 6 dB for horn antennas. These figures represent the maximum power loss that the radiated signal, integrated over a defined ten millisecond interval, can tolerate between the transmit and receive antennas, for a defined signal-to-noise ratio of 10 dB. The performances of typical impulse GPR systems are noted in the literature to lie between 100-130 dB under similar conditions.The system is successfully field tested at various sites, including two open-cut coal mines. The resulting images from these sites demonstrate a penetration depth of at least 80 centimetres and a resolving power of better than 8 centimetres.

show abstract

Electromagnetic Technique of Measuring Coal Layer Thickness

Cited by 16 publications

References 2 publications

Near-surface Interface Detection for Coal Mining Applications using Bispectral Features and GPR

Near-surface Interface Detection for Coal Mining Applications using Bispectral Features and GPR

Snow Stratigraphy and Water Equivalence Measured With an Active Microwave System

Stepped-frequency radar design and signal processing enhances ground penetrating radar performance

Contact Info

Product

Resources

About