Method and apparatus for digital detection of electronic markers using frequency adaptation
First Claim
1. A marker locator, comprising:
- at least one transmitter channel coupled to provide a transmitter signal to an electromagnetic field generator, wherein the transmitter signal is phase shifted to provide a delay phase of substantially zero at the end of an electromagnetic pulse and is capable of exciting multiple types of markers;
at least one receiver channel coupled to receive time decay signals from an electromagnetic field detector; and
a digital processor coupled to provide digitized transmitter output signals to the at least one transmitter channel and to receive digitized time decay signals from the at least one receiver channel,wherein the digital processor receives the digitized time decay signals from the at least one receiver channel in the time interval between pulses of application of digitized transmitter output signals to the at least one transmitter channel, the averages the digitized time decay signals received from the at least one receiver channel, adapts the frequency of the averaged time decay signals, wherein the adapted frequency and the averaged time decay signals can assist in distinguishing between the multiple types of markers.
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Accused Products
Abstract
An electronic marker locator with a digital architecture for providing accurate and consistent estimation of the signal strength is presented. The marker locator includes a Digital Phase-Locked Loop (DPLL) structure. The electronic marker locator transmits known and adjustable frequency bursts corresponding to the markers to be located while synchronously capturing the signals returned from the markers. Because of the convergence properties of the DPLL, very consistent measurements of the reflected marker signal field strength are possible, resulting in both an improvement of maximum detection depth and depth accuracy. Further, the analog front-end hardware can be reduced, offering wider resistance to component tolerances, lower calibration and test times, and flexible frequency selectivity.
63 Citations
21 Claims
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1. A marker locator, comprising:
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at least one transmitter channel coupled to provide a transmitter signal to an electromagnetic field generator, wherein the transmitter signal is phase shifted to provide a delay phase of substantially zero at the end of an electromagnetic pulse and is capable of exciting multiple types of markers; at least one receiver channel coupled to receive time decay signals from an electromagnetic field detector; and a digital processor coupled to provide digitized transmitter output signals to the at least one transmitter channel and to receive digitized time decay signals from the at least one receiver channel, wherein the digital processor receives the digitized time decay signals from the at least one receiver channel in the time interval between pulses of application of digitized transmitter output signals to the at least one transmitter channel, the averages the digitized time decay signals received from the at least one receiver channel, adapts the frequency of the averaged time decay signals, wherein the adapted frequency and the averaged time decay signals can assist in distinguishing between the multiple types of markers. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A marker locator, comprising:
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means for generating pulses of a transmit signal from a frequency, field strength, and phase from one or more markers, wherein these pulses can excite multiple types of markers and each type of marker represents a different type of utility line, wherein generating the transmit signal includes; determining one or more active markers, determining a marker transmit signal to activate the one or more active markers from a frequency, field strength, and phase, wherein the marker transmit signal is phase shifted to provide a delay phase of substantially zero at the end of the electromagnetic pulse, summing the marker transmit signal to form a digital transmit signal, and converting the digital transmit signal to form the transmit signal; means for receiving signals from one or more markers between applications of the transmit signal; means for averaging the received signals to form an average decay signal;
means for determining the frequency, field strength, and phase of one or more markers from the average decay signal, wherein the determined frequency, the determined field strength, and the determined phase can assist in distinguishing between multiple types of markers. - View Dependent Claims (19, 20)
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21. A marker locator, comprising:
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at least one transmitter channel coupled to provide a transmitter signal to an electromagnetic field generator, wherein the transmitter signal is phase shifted and is capable of exciting multiple types of markers; at least one receiver channel coupled to receive time decay signals from an electromagnetic field detector; and a digital processor coupled to provide digitized transmitter output signals to the at least one transmitter channel and to receive digitized time decay signals from the at least one receiver channel, wherein the digital processor receives the digitized time decay signals from the at least one receiver channel in the time interval between pulses of application of digitized transmitter output signals to the at least one transmitter channel, the averages the digitized time decay signals received from the at least one receiver channel, adapts the frequency of the averaged time decay signals, wherein the adapted frequency and the averaged time decay signals can assist in distinguishing between the multiple types of markers, wherein the digital processor includes; a time average that receives the digitized time decay signals from the at least one receiver channel, the digitized time decay signals indicating a signal decay as a function of time following a pulse of the transmitter signal to the at least one transmitter channel, the time average averaging signals over a predetermined number of time intervals between pulses to generate an average decay signal, a marker search that determines a marker structure from the average decay signal generated by the time average, the marker structure including parameters characterizing at least one marker that reflects signals detected by the electromagnetic field detector, a detection digital phase locked loop that receives the marker structure, separates a contribution from each of the at least one marker, determines marker parameters for each of the at least one marker, and generates a transmit array, and a marker transmit output that generates the digitized transmitter output signal of the pulse based on the transmit array and a pulse repetition clock.
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Specification