System and method for locating underground utilities carrying passive signals
First Claim
1. A locator for identifying a passive electromagnetic signal emitted from an underground utility, said locator comprising:
- a portable housing;
an antenna disposed within said housing;
a control circuit; and
a frequency bandpass circuit disposed operatively between said antenna and said control circuit so that said bandpass circuit receives measurement signals from said antenna corresponding to electromagnetic signals received by said antenna and passes to said control circuit a portion of said received measurement signals within a frequency pass band,wherein said control circuit sequentially sets said bandpass circuit to a plurality of different frequency pass bands within a measurement frequency range expected to include a frequency of said passive electromagnetic signal, receives said measurement signal portion corresponding to each said frequency pass band set by said control circuit and selects at least one of said different frequency pass bands corresponding to said frequency of said passive electromagnetic signal based on a predetermined criteria applied to said corresponding measurement signal portions.
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0 Petitions
Accused Products
Abstract
In a method of identifying a passive electromagnetic signal emitted from an underground utility, a portable above-ground antenna is disposed at a location at which the passive electromagnetic signal is expected. Measurement signals are received from the antenna corresponding to electromagnetic signals received by the antenna. The measurement signals are measured at a plurality of different frequency bands within a measurement frequency range expected to include a frequency of the passive electromagnetic signal, and at least one of the plurality of frequency bands is selected based on a predetermined criteria applied to the measurements.
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Citations
28 Claims
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1. A locator for identifying a passive electromagnetic signal emitted from an underground utility, said locator comprising:
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a portable housing; an antenna disposed within said housing; a control circuit; and a frequency bandpass circuit disposed operatively between said antenna and said control circuit so that said bandpass circuit receives measurement signals from said antenna corresponding to electromagnetic signals received by said antenna and passes to said control circuit a portion of said received measurement signals within a frequency pass band, wherein said control circuit sequentially sets said bandpass circuit to a plurality of different frequency pass bands within a measurement frequency range expected to include a frequency of said passive electromagnetic signal, receives said measurement signal portion corresponding to each said frequency pass band set by said control circuit and selects at least one of said different frequency pass bands corresponding to said frequency of said passive electromagnetic signal based on a predetermined criteria applied to said corresponding measurement signal portions. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A locator for identifying a passive electromagnetic signal emitted from an underground utility, said locator comprising:
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a portable housing; an antenna disposed within said housing; a control circuit disposed within said housing, said control circuit including a memory; and a frequency bandpass circuit disposed within said housing operatively between said antenna and said control circuit so that said bandpass circuit receives measurement signals from said antenna corresponding to electromagnetic signals received by said antenna and passes to said control circuit a portion of said received measurement signals within a frequency pass band, wherein said control circuit sequentially sets said bandpass circuit to a plurality of different frequency pass bands within a measurement radio frequency range expected to include a frequency of said passive electromagnetic signal, receives said measurement signal portion corresponding to each said frequency pass band set by said control circuit, stores said corresponding measurement signal portions in said memory, compares signal strengths of said stored measurement signal portions and selects at least one of said different frequency pass bands corresponding to said frequency of said passive electromagnetic signal based on a signal strength comparison. - View Dependent Claims (13, 14)
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15. A method of identifying a passive electromagnetic signal emitted from an underground utility, said method comprising the steps of:
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disposing a portable above ground antenna at a location at which said passive electromagnetic signal is expected; receiving measurement signals from said antenna corresponding to electromagnetic signals received by said antenna; measuring said measurement signals at a plurality of different frequency bands within a measurement frequency range expected to include a frequency of said passive electromagnetic signal; and selecting at least one of said plurality of frequency bands corresponding to said frequency of said passive electromagnetic signal based on a predetermined criteria applied to measurements made at said measuring step. - View Dependent Claims (16, 17, 18, 19, 20)
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21. A method for identifying a passive electromagnetic signal emitted from an underground utility, said method comprising the steps of:
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disposing a portable above-ground antenna at a location at which said passive electromagnetic signal is expected; receiving measurement signals from said antenna corresponding to electromagnetic signals received by said antenna; measuring the strength of said measurement signals at a plurality of different frequency bands within a measurement frequency range expected to include a frequency of said passive electromagnetic signal; comparing signal strengths of said measurement signals from said measuring step; and selecting at least one of said frequency bands corresponding to said frequency of said passive electromagnetic signal based on comparison of said signal strengths. - View Dependent Claims (22)
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23. A method of identifying a passive electromagnetic signal emitted from an underground utility, said method comprising the steps of:
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providing a portable above ground locator comprising a housing, an antenna disposed within said housing, a control circuit, and a frequency bandpass circuit disposed operatively between said antenna and said control circuit and defining a frequency pass band, disposing said portable above ground locator at a location at which said passive electromagnetic signal is expected so that said antenna receives said passive electromagnetic signal and said bandpass circuit receives measurement signals from said antenna corresponding to said passive electromagnetic signal received by said antenna and passes to said control circuit a portion of said received measurement signals within said frequency pass band; activating said control circuit so that said control circuit sequentially sets said frequency bandpass circuit to a plurality of different frequency pass bands within a measurement frequency range expected to include a frequency of said passive electromagnetic signal, receives said measurement signal portion corresponding to each said frequency pass band set by said control circuit, and selects at least one of said different frequency pass bands corresponding to said frequency of said passive electromagnetic signal based on a predetermined criteria applied to said corresponding measurement signal portions. - View Dependent Claims (24, 25, 26, 27, 28)
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Specification