ELECTROMAGNETIC PROXIMITY DETECTION METHOD AND UNIT
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Abstract
Electromagnetic proximity detection method for a buried structure executed with a mobile detection device, including sensing an electromagnetic field emitted from the structure as an analog electrical signal and digitalizing the analog electrical signal as a digital signal, performed after or while filtering the analog and/or digital signal. The proximity of the buried structure is determined by analyzing the digital signal, wherein the detection method can be alternatively executed in at least two of the following modes of detection: Power-Mode of detection, Radio-Mode of detection or Active-Mode of detection. An additional Switching-Mode of operation includes a repeated sequential detection in at least two of the mentioned modes of detection and is done by automatic subsequent alternating of the mode of detection with a minimum rate of alternation that an area of detection is coverable by the at least two modes of detection in a single execution of the detection method.
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Citations
37 Claims
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1-15. -15. (canceled)
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16. An electromagnetic proximity detection method for a buried structure executed with a mobile detection device comprising the steps of:
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sensing an electromagnetic field emitted from the structure as an analog electrical signal; digitalizing the analog electrical signal as a digital signal; filtering the analog and/or digital signal; determining the proximity of the buried structure by analyzing the digital signal; wherein the detecting method can be alternatively executed in at least two of the following modes of detection; a Power-Mode of detection, wherein electromagnetic fields with a fundamental frequency of mains supply are detected;
ora Radio-Mode of detection wherein electromagnetic fields in a range of radio frequencies are detected;
oran Active-Mode of detection wherein electromagnetic fields with a frequency specified by a known signal being artificially introduced to the structure are detected, further comprising an additional Switching-Mode of operation wherein a repeated sequential detecting in at least two of the Power-Mode of detection, Radio-Mode of detection, and Active-Mode of detection is done by automatic subsequent alternating of the mode of detection, wherein the Power-Mode of detection is detecting the structures only based on higher order harmonics of the fundamental frequency of mains supply and the alternating of the mode of detection is done with such a minimum rate of alternation that an area of detection is coverable by the at least two modes of detection in a single execution of the method; and thereby making multiple structures which emit electromagnetic fields of different frequencies accurately detectable by moving the detection device only once over the area of detection. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
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34. An electromagnetic proximity detection method for an underground conduit or wiring at a construction site executed with a mobile detection device, comprising the steps of:
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sensing an electromagnetic field emitted from the structure as an analog electrical signal; digitalizing the analog electrical signal as a digital signal; filtering the analog and/or digital signal; determining the proximity of the buried structure by analyzing the digital signal; wherein the detecting method can be alternatively executed in at least two of the following alternatively selectable modes of detection; a Power-Mode of detection wherein electromagnetic fields with a fundamental frequency of mains supply are detected using electromagnetic fields from power lines with a fundamental frequency of 50 Hz or 60 Hz;
ora Radio-Mode of detection wherein electromagnetic fields in a range of radio frequencies are detected using electromagnetic fields from communication lines emitting radio frequencies in the VLF-band in the range of 15 kHz to 60 kHz;
oran Active-Mode of detection wherein electromagnetic fields with a frequency specified by a known signal being artificially introduced to the structure are detected using an electromagnetic field by an artificially introduced current with a specified frequency of about 8 kHz or 33 kHz; further comprising an additional Switching-Mode of operation wherein a repeated sequential detecting in at least two of the mentioned modes of detection is done by automatic subsequent alternating of the mode of detection, wherein the Power-Mode of detection is detecting the structures only based on higher order harmonics of the fundamental frequency of mains supply and the alternating of the mode of detection is done with such a minimum rate of alternation that an area of detection is coverable by the at least two modes of detection in a single execution of the method, in particular with a rate of at least once or ten times per second, and thereby making multiple structures which emit electromagnetic fields of different frequencies accurately detectable by moving the detection device only once over the area of detection.
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35. A buried structure detection-unit whereby a proximity of a structure is determinable as a distance information according to an electromagnetic field emitted from the structure, wherein the structure is an underground conduit or wiring system at a construction site, the detection-unit being movable above ground and comprising:
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at least two aerials or sensors for sensing an electromagnetic field and providing a corresponding analog signal; a digitalisation means, representing the analog signal as digital signal; an evaluation unit built in a way to determine the proximity of the structure by analyzing the digital signals; and a controller unit; the detection-unit being operateable alternatively in one of at least two of the following detection modes; Power-Mode of detection wherein electromagnetic fields with a fundamental frequency of mains supply are detected as electromagnetic fields from power lines with a fundamental frequency of 50 Hz or 60 Hz;
orRadio-Mode of detection wherein electromagnetic fields in a range of radio frequencies are detected as electromagnetic fields from communication lines emitting radio frequencies in the VLF-band in the range of 15 kHz to 60 kHz;
orActive-Mode of detection wherein electromagnetic fields with a frequency specified by a known signal being artificially introduced to the structure are detected as an electromagnetic field by an artificially introduced current with a specified frequency of about 8 kHz or 33 kHz; wherein the controller unit is built in such a way to automatic subsequent alternate between at least two of the detection modes in a switching mode of operation, wherein, in the Power-Mode of detection, the structures are detected only based on higher order harmonics of the fundamental frequency of mains supply; and the switching mode of operation alternates with such a minimum rate of alternation that an area of detection is coverable by the at least two modes of detection in a single move of the detection unit over the area of detection with a rate of at least once or ten times a second. - View Dependent Claims (36, 37)
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Specification