Patent ID: 12259418

DETAILED DESCRIPTION

The following terminology is used for clarity in the discussion that follows. First, a clear distinction is useful as between a radiated electromagnetic field and guided electromagnetic field such as a guided surface wave.

A radiated electromagnetic field comprises electromagnetic energy that is emitted from a source structure in the form of waves that are not bound to a waveguide. For example, a radiated electromagnetic field is generally an electromagnetic field that leaves an electric structure such as a radio antenna and propagates through the atmosphere or other medium without being guided or bound to any waveguide structure. Once radiated electromagnetic waves leave the electric structure such as a transmitting antenna, the waves propagate through the medium of propagation (e.g., air) independent of the transmission source until energy in the wave eventually dissipates. The radiating wave propagates and dissipates whether the transmission source continues transmitting or not.

Once electromagnetic waves are radiated, they are not recoverable unless intercepted, and if not intercepted the energy inherent in radiated electromagnetic waves is lost forever. Electrical structures such as transmitting antennas are designed to radiate electromagnetic fields by maximizing the ratio of the radiation resistance to the structure loss resistance. Radiated energy spreads out in space and propagates until it dissipates whether a receiver is present or not. This is why radiated electromagnetic waves require a constant supply of power from the transmission source if the transmission is to continue and if the radiating waves are to reach a desired distance at a desired electromagnetic field strength. The energy density of the radiated electromagnetic fields is a function of distance due to geometric spreading. Accordingly, the term “radiate” in all its forms as used herein refers to this form of electromagnetic propagation.

A guided electromagnetic field is a propagating electromagnetic wave whose energy is concentrated within or near boundaries between media having different electromagnetic properties. In this sense, a guided electromagnetic field is one that is bound to a waveguide and may be characterized as being conveyed by the current flowing in the waveguide. If there is no load to receive and/or dissipate the energy conveyed in a guided electromagnetic wave, then no energy is lost except for that dissipated in the conductivity of the guiding medium. Stated another way, if there is no load for a guided electromagnetic wave, then no energy is consumed. The transmission source generating a guided electromagnetic field does not deliver real power unless a resistive load is present. For this reason, the transmission source essentially idles until a load is presented. This is similar to running a generator producing a 60 Hertz electromagnetic wave over a power line where there is no electrical load on the power line. For a guided electromagnetic field or guided electromagnetic wave, this is referred to as “transmission line mode.” Further, guided electromagnetic energy does not continue to propagate along a finite length waveguide after the energy source is turned off. Accordingly, the term “guide” in all its forms as used herein refers to this transmission mode of electromagnetic propagation.

A guided surface wave is an inhomogeneous wave that has a phase velocity greater than the speed of light c. The guided surface wave is the only known surface wave that has a phase velocity greater than the speed of light c. The guided surface wave is inhomogeneous in that it is a transverse magnetic wave that includes both a vertical electric field component oriented in the vertical direction and a horizontal electric field component that is oriented in the direction of propagation of the guided surface wave. Stated another way, an inhomogeneous plane wave is one in which the planes of constant phase (normal to the interface) and the planes of constant amplitude (parallel to the interface) do not coincide. The vertical electric field component of a guided surface wave is vertically polarized and decays exponentially as a function of height.

This contrasts with a radiated electromagnetic wave which is a homogeneous wave in that it has a vertical electric field component and a transverse magnetic field component, where both the electric and magnetic field components fall in a single plane. Accordingly, a radiated electromagnetic wave is also known as a transverse electromagnetic wave.

In some examples described herein, a guided surface wave monitoring system may comprise a mobile metering device having a plurality of measurement subsystems configured to obtain and locally store a plurality of meter measurement data indicative of and/or relevant to a guided surface wave transmitted by a guided surface waveguide probe, wherein the plurality of meter measurement data include a plurality of electromagnetic field measurements, a plurality of weather sensing data, at least one of a plurality of soil sigma measurements selected from an estimated soil sigma measurement and a directly sensed soil sigma measurement, and at least one of a plurality of timestamps, wherein each of the plurality of timestamps is assigned to successive ones of the plurality of meter measurement data being obtained; and at least one remote computing device in communication with the mobile metering device through a network, the at least one remote computing device configured to at least: configure the mobile metering device and deliver settings for corresponding ones of the plurality of measurement subsystems for at least operation at an operating frequency and at a signal conditioning circuit setting; download and store at least a subset of the plurality of meter measurement data locally stored by the mobile metering device; and generate a user interface for display, the user interface indicating a normalized electromagnetic field strength over distance curve of the surface wave from the Zenneck surface waveguide probe to at least an intersecting point of an equivalent radiating wave curve on a substantially timestamp synchronized timeline.

The remote computing device(s) may generate the normalized field strength over distance curve by adjusting at least one of the plurality of electromagnetic field measurements based on substantially similarly timestamped ones of the plurality of meter measurement data selected from the plurality of meter environmental data and the plurality of soil sigma measurements associated with a respective one of the mobile metering device that generated the at least one of the plurality of electromagnetic field measurements.

In some embodiments, a method comprises conveying a mobile metering device having a plurality of measurement subsystems, along a lossy conducting medium relative to a guided surface waveguide probe; obtaining and locally storing a plurality of meter measurement data local to the mobile metering device while being conveyed along the lossy conducting medium, wherein the plurality of meter measurement data is indicative of a guided surface wave transmitted by a guided surface waveguide probe including a plurality of electromagnetic field measurement data, a plurality of weather sensor data, at least one of a plurality of direct soil sigma measurements, and at least one of a plurality of timestamps that correspond to successive ones of the plurality of meter measurement data being obtained; downloading, by a remote computing device, at least a subset of the plurality of meter measurement data locally stored by the mobile metering device; and generating a user interface for display, the user interface indicating a normalized electromagnetic field strength over distance curve of the surface wave from the guided surface waveguide probe to at least an intersecting point of an equivalent radiating wave curve on a substantially timestamp synchronized timeline.

The mobile metering devices may be configured based on operational parameters delivered by the remote computing device that include at least a target frequency of the guided surface wave being monitored and settings for a signal conditioning circuit.

In some embodiments, a mobile metering device may comprise a meter processing system configured to control a plurality of measurement subsystems each configured to obtain and locally store at least one of a plurality of meter measurement data local to the mobile metering device indicative of a guided surface wave at a frequency as low as 1 Kilohertz, the plurality of measurement subsystems include at least: a soil sigma subsystem configured to obtain the respective subset of the plurality of meter measurement data for a plurality of soil sigma measurements; a weather sensor subsystem configured to obtain the respective subset of the plurality of meter measurement data for a plurality of weather sensor data; and a electromagnetic field strength measurement system configured to obtain the respective subset of the plurality of meter measurement data for a plurality of electromagnetic field measurements, the electromagnetic field strength measurement system including at least: a 3-axis antenna; an electromagnetic field meter; a signal conditioning circuit coupled between the 3-axis antenna and the electromagnetic field meter, wherein a low frequency signal detected by the 3-axis antenna is passed through the signal conditioning circuit, the signal conditioning circuit including: at least one signal filter circuit each remotely configurable by way of a signal conditioning interface to operate in at least two operable states of active or inactive; at least one amplification circuit comprising an impedance match circuitry preceding at least two amplifiers in series, the at least one amplification circuit being remotely configurable by way of a signal conditioning interface to operate in any one of at least three operable states selected from a first state wherein the impedance match circuitry and the at least two amplifiers are inactive, a second state wherein the impedance match circuitry and one of the at least two amplifiers are active, or a third state wherein the impedance match circuitry and the at least two amplifiers are active; and wherein the meter processing system is further configured to transmit, upon request by a remote computing environment, locally stored ones of the at least one of the plurality of meter measurement data to the remote computing environment that is accessible to the mobile metering device through a network.

In some embodiments, the 3-axis antenna may be a mobile 3-axis passive multi-turn antenna.

In some embodiments, the signal filter circuit(s) may be selected from at least a low pass filter, a band pass filter, or a high pass filter.

In some embodiments, a metering device may comprise: an at least 3-axis passive multi-loop antenna configured to self-adjust reception of a guided surface wave independent of directional orientation of the at least 3-axis passive multi-loop antenna at a fixed location or while in motion affixed to a conveyance relative to a guided surface wave transmission source; at least one measurement sensor subsystem configured to obtain measurement data relevant to a guided surface wave from a guided surface wave transmission source; and a metering device controller having one or more processors and at least one memory storing executable instructions that, if executed by the one or more processors, cause the one or more processors to perform one or more operations on at least one system or subsystem within operational control of the metering device. Further, the at least one measurement sensor subsystem may include one or more of an electromagnetic field sensor subsystem, an atmospheric condition sensor subsystem, and a soil sigma sensor subsystem.

In some embodiments, the executable instructions, if executed by the one or more processors, may cause the one or more processors to perform one or more further operations comprising: communicating, by way of a network, with at least one primary computing environment located remotely from the metering device; alternatively coupling, in response to a coupling configuration request from the at least one primary computing environment, one of the at least one amplifier and one of the at least one bypass conductor between the 3-axis passive multi-loop antenna and the electromagnetic field sensing meter; performing and reporting on, in response to a configuration verification request received from the at least one primary computing environment, configuration status and settings for one or more system or subsystem within operational control of the metering device; implementing and reporting on, in accordance with configuration data and a configuration request received from the at least one primary computing environment, at least one configuration setting for one or more system or subsystem within operational control of the metering device; activating or deactivating, in accordance with an activate/deactivate request received from the at least one primary computing environment, the metering device or one or more system or subsystem within operational control of the metering device; generating and storing in a local memory a plurality of records in real time, each of the plurality of records including a timestamp and at least one data item obtained concurrently with the timestamp from among the proximate measurement data being obtained by each of the at least one measurement sensor subsystem; and transmitting at least one of the plurality of records from the local memory to the at least one primary computing environment. The transmitting of the at least one of the plurality of records may be triggered by one or more of: a request from the at least one primary computing environment; a regular or random interval timer; a local memory threshold alarm; and availability of the network connecting the metering device and the at least one primary computing environment.

The signal conditioning circuit may further comprise a low pass filter coupled between the at least 3-axis passive multi-loop antenna and the electromagnetic field sensing meter such that the output signal generated by the at least 3-axis passive multi-loop antenna is passed through the low pass filter. In some embodiments, the signal conditioning circuit may further comprise a band pass filter coupled between the at least 3-axis passive multi-loop antenna and an electromagnetic measurement sensor subsystem such that the output signal generated by the at least 3-axis passive multi-loop antenna is passed through the band pass filter.

FIG.1is a graph that shows examples of electromagnetic field strength over distance of a radiation wave and a guided surface wave. The y-axis of graph100depicts electromagnetic field strength in decibels (dB) above an arbitrary reference in volts per meter as a function of distance on the x-axis in kilometers on a log-dB scale. A radiated electromagnetic field strength curve106illustrates the electromagnetic field strength of a radiated electromagnetic field as a function of distance. A guided electromagnetic field strength curve103illustrates the field strength of a guided electromagnetic field over distance. This guided electromagnetic field strength curve103has the characteristics of a transmission line mode curve.

The shape of the radiated electromagnetic field strength curve106propagation and the guided electromagnetic field strength curve103propagation is noteworthy. The radiated electromagnetic field strength curve106has a characteristic linear decay of 1/d, where d is distance on the log-log scale. The guided electromagnetic field strength curve103has a characteristic exponential decay of e−αd/√{square root over (d)} and exhibits a knee109where electromagnetic field strength begins to rapidly drop over distance to a crossover point108with the radiated electromagnetic field strength curve106.

FIG.2illustrates an elevation view of a transmission measurement system120according to various embodiments of the present disclosure. The transmission measurement system120can include, but is not limited to, a plurality of independently functioning systems, subsystems, methods, and apparatus that collectively communicate with each other by at least one network133. Communication across the transmission measurement system120is useful to control and coordinate systems, methods, and apparatus, including but not limited to, data collection, data analysis, data display and replay, measurable aspects relating directly or indirectly to, or are indicative of, or that externally impact, a guided surface wave123. One example of the guided surface wave123is a Zenneck surface wave or other variety of guided surface wave, transmitted by a guided surface waveguide probe122such as a Zenneck surface waveguide probe or other variety of guided surface waveguide probe.

The guided surface wave123transmitted by the guided surface waveguide probe122travels along the surface of a lossy conducting medium124. The lossy conducting medium124may comprise, as one example, a terrestrial medium such as the Earth's surface. On Earth, a terrestrial medium may comprise some or all structures and formations thereon whether natural, man-made, or refined by man. Examples of natural elements include, but are not limited to, rock, soil, sand, fresh water, sea water, minerals, trees, vegetation, and all other natural elements that make up the planet Earth. Examples of man-made elements include, but are not limited to, concrete, asphalt, metals, composites, building materials of any type, and other man-made materials whether conductive or non-conductive. In other embodiments, the lossy conducting medium124may comprise some medium other than the Earth, whether naturally occurring or man-made. For the Earth's surface as the lossy conducting medium124, an atmospheric medium125is adjacent to the lossy conducting medium124and comprises a mix of gases and other elements, collectively referred to herein as “air,” that make up an atmospheric layer above the Earth's surface.

The guided surface waveguide probe122is a simplified representation of any type of guided surface waveguide probe including but not limited to a Zenneck surface waveguide probe that may be employed. Nonlimiting examples of guided surface waveguide probes and further details are described in the following Patent Cooperation Treaty Applications Publications: Patent Cooperation Treaty Application Publication WO2014/137817 published on Sep. 12, 2014, Patent Cooperation Treaty Application Publication WO2016/039832 published on Mar. 17, 2016, Patent Cooperation Treaty Application Publication WO2016/195738 published on Dec. 8, 2016, and Patent Cooperation Treaty Application Publication WO2018/164965 published on Sep. 13, 2018. Other apparatus and configurations that produce a guided surface wave123are described in U.S. patent application Ser. No. 16/708,048 filed on Dec. 9, 2019 (now U.S. Pat. No. 11,340,275 issued May 24, 2022) entitled “Anisotropic Constitutive Parameters for Launching a Zenneck Surface Wave,” and U.S. patent application Ser. No. 17/683,847 filed on Mar. 1, 2022 entitled “Anisotropic Constitutive Parameters for Launching a Zenneck Surface Wave.”

The transmission measurement system120includes a plurality of metering devices126a-N that may be positioned on and/or above the lossy conducting medium124within the atmospheric medium125. According to various embodiments, each of the plurality of metering devices126a-N may be positioned individually at a point along the lossy conducting medium124as illustrated in the elevation view ofFIG.2. The intervals can be a regular distance d1-nfrom the guided surface waveguide probe122, or irregular distances, or at a mix of regular and irregular distances, in which case the interval between two respective distances d1-nmay be denoted as the interval dx−dx-1varies.

FIG.3depicts example placements of metering devices of the transmission measurement system according to various embodiments of the present disclosure. Metering devices126a,126b,126c,126d, and126eare depicted as being positioned at intervals that are as regular as is practical and as linearly aligned with one another relative to a linear radial originating at the guided surface waveguide probe122as circumstances permit. Circumstances impacting the interval between any two metering devices126a-126eand/or their linear alignment relative to the guided surface waveguide probe122may be the result of any one or combination of factors including but not limited to terrain, manmade structures, obstacles, access to power, access to network133, property owner permissions, and the like. To the extent conductivity (σ) and permittivity (ε) of the atmospheric medium125(i.e., air) and the lossy conductive medium124(e.g., Earth's surface) vary among the various locations of the metering devices126a-126e, raw electromagnetic field strength measurements produced by each of the metering devices126a-126eat each location may benefit from normalization or other adjustments based on local measurements of local weather and the conductivity (σ) and permittivity (ε) of the ground at each metering device location126a-126e. As will be discussed, adjustments and normalization of data across the entire end-to-end distance of the guided surface wave123being monitored may promote meaningful data analysis, graph plotting, and an overall uniform understanding of the behavior and characteristics of the guided surface wave123and the performance of the guided surface wave guide probe122.

Returning toFIG.2, the transmission measurement system120may further include a primary computing environment127coupled to a network133. The primary computing environment127may include, but is not limited to, at least one processor circuit, for example, such as a primary processor129and a primary memory130, both of which are coupled to a primary interface132. The primary computing environment127may comprise, for example, at least one server or apparatus having a similar purpose. Primary interface132may comprise, as one example, a data bus with an accompanying address/control bus or other bus structure as can be appreciated.

Stored in the primary memory130may be both data and several components that are executable by the primary processor129. In the illustrated example, stored in the primary memory130and executable by the primary processor129are a primary meter controller143, a primary clock144, and potentially other applications. Alternatively, the primary clock144may reside within the circuitry of the primary processor129as can be appreciated. In addition, an operating system may be stored in the primary memory130and executable by the primary processor129.

It is understood that there may be other applications that are stored in the primary memory130and are executable by the primary processor129as can be appreciated. Where any component discussed herein is implemented in the form of code, any one of a number of programming languages may be employed such as, for example, C, C++, C#, Objective C, Java, Javascript, Perl, PHP, Visual Basic, Python, Ruby, Delphi, Flash, or other programming languages.

The primary meter controller143may be stored in the primary memory130and is executable by the primary processor129. In this respect, the term “executable” means a program file that is in a form that can ultimately be run by the primary processor129. Examples of executable programs may be, for example, a compiled program that can be translated into machine code in a format that can be loaded into a random access portion of the primary environment memory130and run by the primary processor129, source code that may be expressed in proper format such as object code that is capable of being loaded into a random access portion of the primary memory130and executed by the primary processor129, or source code that may be interpreted by another executable program to generate instructions in a random access portion of the primary memory130to be executed by the primary processor129, etc. An executable program may be stored in any portion or component of the primary memory130including, for example, random access memory (RAM), read-only memory (ROM), hard drive, solid-state drive, USB flash drive, memory card, optical disc such as compact disc (CD) or digital versatile disc (DVD), floppy disk, magnetic tape, or other memory components.

The primary memory130is defined herein as including both volatile and nonvolatile memory and data storage components. Volatile components are those that do not retain data values upon loss of power. Nonvolatile components are those that retain data upon a loss of power. Thus, the primary memory130may comprise, for example, random access memory (RAM), read-only memory (ROM), hard disk drives, solid-state drives, USB flash drives, memory cards accessed via a memory card reader, floppy disks accessed via an associated floppy disk drive, optical discs accessed via an optical disc drive, magnetic tapes accessed via an appropriate tape drive, and/or other memory components, or a combination of any two or more of these memory components. In addition, the RAM may comprise, for example, static random access memory (SRAM), dynamic random access memory (DRAM), or magnetic random access memory (MRAM) and other such devices. The ROM may comprise, for example, a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or other like memory device.

The primary processor129may represent multiple processors and the primary memory130may represent multiple memories that operate in parallel processing circuits, respectively. In such a case, the primary interface132may be an appropriate network that facilitates communication between one or more of the primary processor129, and one or more of the primary memory130. The primary interface132may comprise additional systems designed to coordinate this communication, including, for example, performing load balancing. The primary processor129may be of electrical or of some other available construction.

The primary computing environment127may also comprise various devices such as, for example, one or more programmable logic controllers or other types of computing devices.

The primary computing environment127is coupled to and in communication with the network133. The network133may comprise, for example, General Purpose Interface Bus (GPIB) connections corresponding to IEEE 488.2, the Internet, intranets, extranets, wide area networks (WANs), local area networks (LANs), wired networks, wireless networks, or other suitable networks, etc., or any combination of two or more such networks. For example, such networks can include satellite networks, cable networks, Ethernet networks, and other types of networks as a matter of design choice or availability.

The primary computing environment127may also be in communication with a data server131. The data server131may be coupled directly to the primary computing environment127or the primary computing environment127may communicate with data server131through a public or private network such as network133. One or more of the metering devices126a-N may also be coupled to and have fully enabled access to network133such that a coupled metering device may be individually in data communication with the primary computing environment127.

A server data store146may exist in or be communicatively coupled to data server131. Server data store146may comprise, for example, a database or other data storage structure. A display device149may be coupled to the primary computing environment127, and at minimum standard input/output devices are coupled to the primary computing environment127. The primary meter controller143may perform various functions including configuring the metering devices126a-N for operation, obtaining meter measurement data153and potentially other information from the metering devices126a-N, and storing such meter measurement data153in the server data store146. In addition, the primary meter controller143may render various user interfaces156on the display device149.

Various data is stored on the server data store146that may be written, accessed, or changed by the primary meter controller143executed on the primary computing environment127. Types of data stored on server data store146is without limit. As one nonlimiting example in the context of a transmission measurement system120, types of data can include but are not limited to, meter measurement data153which are data collected from the plurality of metering devices126a-N. The meter measurement data153within server data store146may include, for example, a plurality of server records159, each server record being a copy of data collected by a given one of the plurality of metering devices126a-N. Data within a server record159may include, but is not limited to, data fields such as, a session identifier163, a meter identifier166, a timestamp169, electric field measurements173, magnetic field measurements176, metering device location179(e.g., coordinates), in-situ meter configuration183, meter weather data186, soil sigma data187, and other data fields relating to the monitored operational status and measurements of the probe and/or near-field measurements inside the crossover point and inside the safety perimeter.

A server record159may be associated with a metering device126by a meter identifier166. Each of the metering devices126a-N may be uniquely identified by a meter identifier166.

Measurements taken over an amount of time by a given metering device126may be identified in server record159by a session identifier163. There may be multiple amounts of time in which measurements are collected and each amount of time may be identified by a session identifier163. Alternatively, there may be multiple server records159having the same session identifier163that may represent continuous measurements taken by a given metering device126over a span of hours, days, or weeks. In another embodiment a session recording identifier163may represent measurements collected by all or a given one of the metering devices126a-N during a span of time in which the configuration of a given metering device126or the guided surface waveguide probe122has been reconfigured or altered in some way to determine the effect of the change to the guided surface wave123or the ability to measure aspects of the guided surface wave123.

Timestamp169represents the time when the data within a given server record159was collected by a given one of the metering devices126. Each metering device126a-N includes a local clock361to generate the timestamp169when such metering device126a-N captures measurements and populates a local record159.

Electric field measurement173may comprise a raw measurement of the electric field at the location of a measuring one of the plurality of metering devices126a-N. The electric field measurement173may comprise one reading or multiple readings of the electric field of guided surface wave123taken across a single axis or across multiple different axes (e.g., 3 axes, 6 axes).

Magnetic field measurement176comprises a raw measurement of the magnetic field at the location of a measuring one of the plurality of metering devices126a-N. The magnetic field measurement176may comprise multiple measurements taken along a single axis or across multiple axes (e.g., 3 axes, 6 axes).

Electromagnetic field measurements173/176taken by a fixed-position metering device126may benefit from the deployment of a mobile metering device to supplement measurements taken by fixed position metering devices126a-N. A 6-axis metering device can further supplement the measurement data with the determination of the Poynting vector for the guided surface wave123. Further, electromagnetic field measurements173/176may comprise a trace of multiple measurements taken across a frequency range. A given trace may be specified in terms of a center frequency and a span, a center frequency with a low and high frequency, or such a trace can be defined in some other manner. A predefined number of electromagnetic field measurements173/176may be taken within a given trace, where each measurement is taken at predefined intervals across the frequency spectra of the trace. In one embodiment, up to 1000 or more different electromagnetic field measurements173/176may be taken in a single trace that are evenly spaced across the frequency spectrum of the trace. The number of electromagnetic field measurements173/176that are taken can be any number of measurements reasonably obtained during normal operation over a given time. The electromagnetic field measurement173/176at the center frequency of a trace may be the ultimate frequency of interest, where the remaining measurements of the trace may indicate a degree of noise in the frequency spectra of the trace or may indicate other information.

Meter location179identifies a geographical location of a given one of the plurality of metering devices126a-N. The meter location179may be expressed in terms of geographical coordinates, GPS coordinates, or other coordinate system.

In-situ meter configuration183includes one or more parameters with which each of the metering devices126a-N and their measuring subsystems were configured for operation. Such a configuration may include the target frequency where electric and magnetic field strengths are to be measured, metering device antenna orientation, the intervals between measurements being taken, among others. The in-situ meter configuration183may also specify information about the traces of electromagnetic field measurements173/176such as a center frequency and span, a center frequency and low and high frequencies of the span, or other information specifying where measurements are taken. Such parameters may also include configuration data that determines how a Fourier transform is performed, if any, and the units of measure such as millivolts per meter or volts per meter, etc. Given in-situ meter configuration183stored in the server records159, the state of the respective metering device126a-N may be known at the time that the electromagnetic field measurements were taken.

Local weather data186may include meteorological and environmental data proximate to a measuring one of the plurality of metering devices126a-N. At least one or more meteorological and/or environmental sensors can be deployed to collect data including, but not limited to, a thermometer for temperature measurements, a barometer for air pressure measurements, a hygrometer for water vapor measurements, a sling psychrometer for humidity measurements, rain and/or snow gauges for precipitation measurements, an anemometer for wind speed measurements, and/or a wind vane for wind direction measurements. Meteorological and environmental measuring instruments may be configured to generate a measurement of at least one factor associated with the weather and environment proximate to respective ones of the plurality of metering devices126a-N. Other sensors may be included such as an accelerometer to detect undesirable movement of any one of the plurality of metering devices126a-N. A global positioning system (GPS) sensor and/or a compass can be included to sense position and orientation of a respective one of the plurality of metering devices126a-N. Sensing and collecting local meteorological, weather, and environmental data proximate to each of the plurality of metering devices126a-N facilitates an understanding of what is happening in the atmospheric medium125(i.e., air) immediately above the lossy conducting medium124(i.e., Earth surface, soil). Moisture content and temperature of the air is continuously changing and is an important external factor impacting the conductivity and permittivity of the air. Measuring and recording the components contributing to moisture content and temperature (i.e., weather factors generally) facilitates the ability to accurately adjust raw measurements of electric field173and magnetic field176strength which can otherwise result in an inaccurate interpretation of a strong, weak, or otherwise skewed field strength reading of the guided surface wave123at the location of a given one of the plurality of metering devices126a-N.

Soil sigma data187collected from sensors in the soil facilitate an understanding of the conductivity and permittivity of the soil proximate to each of the plurality metering devices126a-N. Reasons for collecting data to track the ever-changing conductivity and permittivity in soil are similar to the reasons for air. Sensing and collecting local soil sigma data proximate to each of the plurality of metering devices126a-N facilitates an understanding of what is happening in the lossy conducting medium124(i.e., Earth surface, soil). Analyzing a core sample of geological stratification and content of the top 10 meters of surface soil local to each of the plurality of metering devices126a-N (sampling less depth or more depth as location and situation dictates) is informative as to the expected conductivity and permittivity of the soil, but soil sigma sensors may be used to measure the ongoing ever-changing moisture content of the soil at each location. Moisture content and temperature of the soil are continuously changing and are important external factors impacting the conductivity and permittivity of the soil. Soil sigma measurements to monitor the moisture content and temperature of the soil along with corresponding measurements for the air, facilitate accurate adjustments to raw measurements of electric field173and magnetic field176strength. Without these air and soil measurements at the location of each metering device126a-N and the adjustment factors they provide, inaccurate interpretation of a raw electromagnetic field strength reading relative to the guided surface wave123can result.

Other sensors may also be included to determine the status of the various component devices and measurement subsystems within and under the control of each of the plurality of metering devices126a-N. These additional sensors can include, but are not limited to, tamper switches, battery condition sensors, power input sensors, and other operational parameter sensors may be used. A tamper switch can indicate that a third party has tampered with a metering device126or its local equipment by opening a cover. Wind, rain, moving water, landslides and the like can also be detected by appropriate sensors and reporting. Battery condition sensors provide the current status of any batteries that are used to power or provide back-up power to any one or more of the plurality of metering devices126a-N. Power input sensors may indicate whether the input power to the metering devices126a-N is experiencing problems such as low voltage or other conditions, where the power may be obtained from external utility sources, solar panels, or other sources.

Returning to the discussion of primary computing environment127inFIG.2, a primary meter controller143may be executable in the primary computing environment127to configure the operation of the metering devices126a-N, obtain records159from the metering devices126a-N, generate and render user interfaces156on the display device149that depict the electric and magnetic field measurements173/176of the records159obtained, and/or other functions.

Primary memory130or other memory accessible to the primary computing environment127may store data about the metering devices126a-N within a meter record193. Each meter record193may include, but is not limited to, configuration data196that are the operational settings that can be used to configure or reconfigure each of the metering devices126a-N. The in-situ meter configuration183data represent the last known set of configuration settings for a given metering device126.

The user interface156rendered on the primary display device149may be generated by the primary meter controller143. User interface156may be configured to display any one of the available meter measurement data153types or combinations of such data based on a predefined rotation of displays or as a user selection on demand, for example.

External clock199represents one or more external clocks of particular accuracy to which the primary clock144and local clock361in each of the plurality of metering devices126a-N can be synchronized. Synchronizing to external clock199ensures system wide accuracy of timestamps169and the operational coordination cross the transmission measurement system120. External clock199represents an Internet clock, an atomic clock, or other high-accuracy clock as can be appreciated.

Given the introduction of the various components of the transmission measurement system120set forth above, a further operational disclosure is provided. To begin, assume that it is desired to determine the signal output of a guided surface waveguide probe122. To accomplish this end, individual ones of a plurality of metering devices126a-N may be positioned along the lossy conducting medium124relative to the guided surface waveguide probe122. The metering devices126a-N are each positioned at desired distances d1-Naway from the guided surface waveguide probe122. The position and precise distance of any one of the plurality of metering devices126a-N may depend in part on desirable or undesirable geographical features, man-made structures, availability of power, public and private land access rights, or other physical or practical limitations. Positioning and/or conveying each of the metering devices126a-N is commonly performed and controlled manually but can be implemented in whole or in part by a self-deploying configuration or remote drone deployed metering device126, for example, as logistical situations and available deployment technologies dictate. By whatever means a metering device126is deployed in the field for the first time or as a replacement, a battery of certification, sanity, and readiness checks may be performed manually and/or remotely to verify the metering device's configuration and confirm the device's readiness for operation as well as all sensor subsystems accompanying and under the control of respective ones of the plurality of metering devices126a-N.

The following discussion relates to metering devices126a-N that have been individually or collectively as a group or subgroup deployed and certified as ready for operation. Each of the plurality of metering devices126a-N and any one or all sensing subsystems associated with each of the plurality of metering devices126a-N can be configured for operational use prior to sensing and collecting data. A user may proceed to cause the primary meter controller143to activate and configure an individual one or a group of the plurality of metering devices126a-N and their respective sensor subsystems for operation. In one nonlimiting embodiment, activating one or more metering devices126a-N can be manually done by a user at a metering device126location and proceed to also activate any one or more of its local sensor subsystems as desired. In another nonlimiting embodiment a user can cause the primary meter controller143to send an activate instruction to any one or more of the plurality of metering devices that are to be activated. In another nonlimiting embodiment the primary meter controller143can be configured to cause any one or more of the metering devices126a-N to activate based on elapsed time, operational or situational status, or any other reason or occurrence resulting in the determination that one or more of the plurality of metering devices126a-N are to be activated. Activating a specific one or more of the plurality of metering devices126a-N may be accomplished by accompanying an activate instruction with a meter identifier166of the metering device126that is to be activated. The plurality of metering device126a-N may be deactivated in a similar manner.

Configuring activated ones of the plurality of metering devices126a-N establishes operational parameters for nominal operation of each device and their accompanying sensor subsystems. A user may enter or otherwise specify the configuration data196and a meter identifier166for any one or more of metering devices126a-N being configured. Configuration data196can be input using various input devices such as a keyboard, mouse, voice, or other input means. Various user interfaces may be created that present mechanisms such as drop-down menus, picklists, input fields, and other mechanisms to facilitate entry of the configuration data196.

Configuration data196is stored in the primary memory130or other memory as mentioned above. Thereafter, the primary meter controller143communicates the configuration data196to each of the metering devices126a-N that are to be used in obtaining electromagnetic field measurements173/176.

The primary meter controller143may ensure that the clocks that generate the timestamps169in each of the metering devices126a-N are accurate. In one approach, this may be accomplished by ensuring the accuracy of the primary clock144relative to external clock199. The primary meter controller143may communicate with each of the metering devices126a-N to obtain a timestamp169from each for comparison. Corrective action is taken for any local clock producing a timestamp169outside a predetermined tolerance. Other approaches may be employed to synchronize clocks across the transmission measurement system120.

A metering device126can proceed to configure and initialize (e.g., power up, attain operational status, and/or the like) based on the configuration data196received from the primary meter controller143. Whether implementing new operational settings from configuration data196or confirming existing operational settings, respective ones of the metering devices126a-N may communicate operational readiness to the primary meter controller143and measurement activities begin for the respective metering devices126a-N.

During the acquisition and storing of meter measurement data153in respective ones of the plurality of server records159, the primary meter controller143may generate the user interface156to display the incoming meter measurement data153on the display device149. One example of the user interface156generated by primary meter controller143can include but is not limited to, a raw electromagnetic field strength over distance curve226from select ones of the electromagnetic field measurements173/178obtained from a plurality of the metering devices126a-N monitoring the guided surface wave123generated by the guided surface waveguide probe122. Such electromagnetic field strength may be the magnetic field strength176or the electric field strength173. The primary meter controller143may also generate an adjusted or normalized electromagnetic field strength curve226by factoring all relevant meter measurement data153that can influence electromagnetic field strength, including but not limited to local weather data186and soil sigma data187. Corrective curve fitting techniques may also be employed where data is missing for any reason along the curve. Primary meter controller143may generate other reference curves that may be presented in the user interface156for purposes of comparison with the curve representative of the transmission of the guided surface waveguide probe122as will be described.

FIG.4is an example of a graphical user interface generated by the transmission measurement system according to various embodiments of the present disclosure. User interface156depicts a theoretical 100% efficient electromagnetic field strength over distance curve223for a given frequency. This provides a reference curve for a perfect operational scenario at a given frequency for a guided surface wave123transmitted by a guided surface waveguide probe122at a given distance.

Primary meter controller143may use curve fitting techniques to calculate a near real time adjusted or normalized electromagnetic field strength over distance curve226based on collected data at each metering device location, including but not limited to electromagnetic field strength measurements173/176, local weather data186, and soil sigma data187. While the term “near real time” is used herein, it is understood that there will be a delay of a very short period of time after the electromagnetic field measurements173/176are generated to communicate the local records159from the metering devices126a-N and to access meter measurement data153from the server data store146and generate the real time curve226. Given that this delay is relatively small, the curve is considered to be generated in near real time.

A radiating wave over distance curve229may also be plotted on user interface156as a worse case reference in the event the guided surface waveguide probe122were transmitting only radiating waves over distance rather than a guided surface wave over distance with a knee resembling the perfect scenario surface wave curve233.

FIGS.5A and5Billustrate flow diagram examples of functionality implemented by the transmission measurement system according to various embodiments of the present disclosure.FIG.5Aillustrates a flow diagram of one example of the operation of a portion of the primary meter controller143according to various embodiments. It is understood that the flowchart ofFIG.5Aprovides merely an example of the many different types of functional arrangements that may be employed to implement the operation of the portion of the primary meter controller143as described herein. Alternatively,FIG.5Amay be viewed as depicting an example of steps of a method implemented in the primary computing environment127according to one or more embodiments.

At box253, the primary meter controller143initializes communication with each metering device126a-N. This step is performed, for example, to make sure that the respective metering devices126a-N are in an active state and ready to operate. For example, various metering devices126a-N may be inactive, broken, shut down completely due to lack of power, or are presently not needed.

Once the primary meter controller143has heard from all or at least an acceptable number of the respective metering devices126a-N to facilitate operation, the primary meter controller143proceeds to box256where an initial configuration routine is called with respect to each of the metering devices126a-N. This initial configuration routine places each metering device126a-N in a state that facilitates the taking of electromagnetic field measurements173/176, local weather data186, and soil sigma data187, among other measurements as desired in accordance with the various aspects of the present disclosure. Once the initial configuration routine is executed with respect to each metering device126a-N and their sampling subsystems are properly configured to take measurements and send the local records159to the primary meter controller143, the primary meter controller143proceeds to box259.

At box259, the primary meter controller143initiates the downloading of local records159of meter measurement data153acquired and locally stored by respective ones of the metering devices126a-N. Thereafter, the primary meter controller143proceeds to box263.

At box263, the primary meter controller143begins a loop for each of the metering devices126a-N. The primary meter controller143proceeds to box266to determine whether a respective one of the metering devices126a-N is currently shut down. This is done because the metering devices126a-N may be configured to shut down intermittently or periodically and restart to conserve power, or avoid long term overheating, or devices not needed, or other potential problems due to long-term operation. If the respective metering device126a-N under consideration is currently shut down, then the primary metering controller143proceeds to box269where the next metering device126a-N is identified for consideration in the loop. Thereafter, the primary meter controller143reverts back to box266as shown.

Referring back to box266, if the primary meter controller143determines that the current metering device126a-N is not shut down, then the primary meter controller143proceeds to box273.

At box273, the primary meter controller143determines whether the current metering device126a-N under consideration has been initialized for operation. If not, then the primary meter controller143proceeds to box276. Otherwise, the primary meter controller143proceeds to box279.

At box276, the primary meter controller143calls an initial configuration routine with respect to the current metering device126a-N under consideration to configure such metering device126a-N for operation. Thereafter, the primary meter controller143proceeds to box269. However, assuming that the current metering device126a-N has been previously initialized, then the primary meter controller143proceeds to box279.

At box279, the primary meter controller143requests one or more data records159from the currently designated metering device126a-N. In the case that the metering device126a-N is configured to store records159in a local data buffer, then the primary meter controller143may request and receive all of the currently stored records159in the data buffer of the respective metering device126a-N. In the case that the respective metering device126a-N does not actually store the records159in a local data buffer, in box279the primary meter controller143sends a request to the respective metering device126a-N to obtain an electromagnetic field measurement173/176and send the same back to the primary meter controller143in the form of a record159that includes all other data as described above. Thereafter, the primary meter controller143proceeds to box283.

At box283, the primary meter controller143stores one or more data records159received from the respective one of the metering devices126a-N in the server data store146. The electromagnetic field measurements173/176included within such records159are then available to be accessed from in the server data store146by the primary meter controller143to generate the user interface156as mentioned above. To ensure that the maximum efficiency curve233is as up to date as possible, it may be desirable to download the records159from the respective metering devices126a-N as frequently as possible with relatively low data communication latency. As such, it may be desirable to avoid significant storage of local records159in local data buffers of metering devices126a-N in cases where the metering devices126a-N include local buffering capability for the temporary storage of local data records159.

At box286, a delay may be implemented in situations where it is desirable. Such circumstances may exist, for example, when a number of metering devices126a-N are currently being initialized or other circumstances may warrant a delay in the loop. In another example, it may be the case that it is desirable that a certain number of local records159are stored in a local data buffer in the respective metering devices126a-N before such records159are downloaded to the server data store146by the primary metering controller143.

At box289, the primary meter controller143determines whether the current data acquisition loop is to continue or whether the data acquisition by the metering devices126a-N is to end. The determination as to whether the loop is to continue may depend upon an appropriate operator input that indicates that the data acquisition by the metering devices126a-N is to cease. Such might be the case, for example, when a test of a respective guided surface waveguide probe122has completed or the data acquisition may be stopped for some other reason.

If the primary meter controller143determines that the data acquisition loop is to cease in box289, then the primary meter controller143proceeds to box293. Otherwise, the primary meter controller143continues at box269where the next metering device126a-N is designated. Thereafter, the primary meter controller143reverts back to box266as was noted above.

At box293, the primary meter controller143implements a shutdown of the metering devices126a-N. This may be done by issuing a command to the metering device is126a-N that they are to alter their states to a stand-by or powered down state. Such a stand-by or powered down state may involve powering down all unessential components with the exception of those subsystems or components that will allow the metering devices126a-N to communicate in the future to perform additional data acquisition in terms of obtaining electromagnetic field measurements173/176and other information to generate the records159for tests of future versions of guided surface waveguide probes122.

Thereafter, the operation of this portion of the primary meter controller143ends as shown.

FIG.5Bis a flow diagram showing one example of the operation of another portion of the primary meter controller143comprising the initial configuration routine that is implemented to initialize the operation of the metering devices126a-N according to various embodiments. It is understood that flow diagramFIG.5Bis an example of the many different types of functional arrangements that may be employed to implement the operation of the portion of the primary meter controller143as described herein. As an alternative, the flow diagramFIG.5Bmay be viewed as depicting an example of steps of a method implemented in the primary computing environment127according to one or more embodiments.

At box296, the primary meter controller143implements a synchronization of the clocks in all of the metering devices126a-N. Various approaches may be used to accomplish this task. For example, in the case that the primary meter controller143seeks to synchronize the clocks of the metering devices126a-N with the primary clock144that is local to the primary meter controller143, then the primary meter controller143may request each of the metering devices126a-N to provide a timestamp169. Any time differential or time delta between the time set forth by the primary clock144and the timestamp169is then determined, while accounting for any data communication latency between a respective metering device126a-N and the primary computing environment127. Thereafter, the primary meter controller143sends a message to the respective metering device126a-N that directs the respective metering device126a-N to alter its local clock based upon the time delta calculated.

As an additional alternative, the primary meter controller143may send a message to each of the metering devices126a-N to take action to synchronize their local clocks361with external clock199to which the primary clock144for the primary meter controller143is also synchronized. In addition, there may be other approaches used to synchronize the clocks in each of the metering devices126a-N with the primary clock144as can be appreciated. In addition, the primary meter controller143may intermittently or periodically synchronize the primary clock144with external clock199such as an atomic clock that is available over the Internet or other reference clock as can be appreciated.

Once the respective clocks in the primary computing environment127and the metering devices126a-N are synchronized in box296, the primary meter controller143proceeds to box299to communicate the configuration data196to the respective metering devices126a-N so that they may be configured for operation in acquiring electromagnetic field measurements173/176and generating respective local data records159that include such electromagnetic field measurements173/176. Once each of the metering devices126a-N have confirmed that they are properly configured for operation, the initial configuration routine of the primary meter controller143ends and the operation of the primary meter controller143reverts back to box256discussed above.

FIG.6illustrates a flow diagram example of functionality implemented by the transmission measurement system according to various embodiments of the present disclosure.FIG.6is an example of many different types of functional arrangements that may be employed to implement the operation of the portion of the primary meter controller143as described herein. As an alternative, theFIG.6flow diagram may be viewed as depicting an example of steps of a method implemented in the primary computing environment127according to one or more embodiments.

At box303, the primary meter controller143initializes operation with respect to generating the graphical user interface156. At box306, the primary meter controller143determines a timestamp169that provides a time at which readings of a given transmitted signal were measured by the metering devices126a-N and are included in the server records159stored in the server data store146, where the user interface156is generated from such readings. In one embodiment, when determining the timestamp169, the primary meter controller143may simply identify the latest timestamp169within the server records159such that the user interface156is generated from the data generated by the most recent attempt to launch a guided surface wave123. Alternatively, a user may enter a reference time of interest and the primary meter controller143may then proceed to identify the timestamp169within the server records159that is closest to the reference time. To this end, the desired electromagnetic field measurements173/176may not be the latest electromagnetic field measurements that are taken if the operator wishes to review the electromagnetic field strength per distance that occurred during a previous test in the past. Alternatively, there may be other approaches used to identify the specific timestamp169within the server records159that points to a specific record from which data is used to generate the user interface156.

At box309the primary meter controller143obtains all of the server records159that include such timestamp169from the server data store146. Alternatively, select ones of the electromagnetic field measurements173/176in records159that have a timestamp169within a predefined time tolerance of a predefined time may be used to generate the curve of electromagnetic field strength over distance226. Alternatively, the electromagnetic field measurements173/176in records159that were generated by the respective metering devices126a-N within a predefined time period are used to generate the curve of electromagnetic field strength over distance226. In addition, other approaches may be used.

At box313, the primary meter controller143may alter or normalize the magnetic or electric field measurements173/176of the currently considered server records159based upon predefined parameters including but not limited to local weather data186and soil sigma187. For example, it may be the case that respective ones of the metering devices126a-N are installed at different heights. As a result, the electromagnetic field measurements173/176obtained from such metering devices126a-N might need to be adjusted to account for the height differences given that a guided surface wave123can decay exponentially with increasing height above the lossy conducting medium124. In addition, the physical makeup of the sites where the respective metering devices126a-N are located such as the makeup of the soil or the presence of man-made structures may affect the measurements taken and a correction factor must be applied to the electromagnetic field measurements173/176from a respective record159. In this manner, the electromagnetic field measurements173/176may be adjusted based on a correction factor associated with the respective metering device126a-N that generated the one or more electromagnetic field measurement(s)173/176themselves.

At box316respective magnetic and/or electric field measurements173/176from the respective server records159stored in the server data store146are plotted as one or more data points on the graph223of the graphical user interface156to be rendered on the display device149. Thereafter, at box319, the primary meter controller143proceeds to generate the near real time curve226based upon the current data points on the graphical user interface156that is to be rendered on the display device149. That is to say, each time new data points are plotted in the graph223, a new near real time curve226is generated based upon curve fitting techniques to update the near real time curve226.

At box323, the primary meter controller143proceeds to generate the reference curves in the graph223of the graphical user interface156as was mentioned above. In some environments, such reference curves may not be created at all and the functionality of box323may be skipped. The reference curves may include, for example, the equivalent radiating wave over distance curve229or the maximum efficiency curve233mentioned above with reference toFIG.4.

At box326the current graphical user interface156embodied in the primary memory130of primary computing environment127is rendered on the display device149. If the most recent electromagnetic field measurements173/176from the most recently generated server records159having the specified timestamp from the respective metering devices126a-N are included in the graphical user interface156, then the near real time curve226will be as close to real time as possible.

At box329, the primary meter controller143determines whether it is to continue generating the most up-to-date graphical user interface156on the display device149by determining whether it should proceed to the next most recent timestamp169. Specifically, it may be the case that the user only wants to see a graph of the readings from a given time without trying to depict the readings over time. Alternatively, the primary meter controller143may be directed to create a near real time depiction of the readings from the records159as they are created and stored by the metering devices126a-N. If a near real time depiction of the readings is desired, the primary meter controller143proceeds to box333where the next timestamp169is identified for which the most recent electromagnetic field measurements173/176(or other field measurement) taken from the most recent records159is to be plotted on the graph223of the graphical user interface156. Thereafter, the primary meter controller143reverts back to box309as shown. Otherwise, the primary meter controller143ends. The determination in box329as to whether to end the loop that is used to generate the graphical user interface156may depend upon user input that causes the display of the electromagnetic field output of the guided surface waveguide probe122to stop.

FIG.7is a schematic block diagram example of a metering device in the transmission measurement system according to various embodiments of the present disclosure. The metering device126includes a meter processing system353having a processor circuit that includes a local processor356and a local memory359, both of which are coupled to a local interface363. To this end, the meter processing system353may comprise, for example, one or more computing devices such as programmable logic controllers or other computing devices. The local interface363may comprise, for example, a data bus with an accompanying address/control bus or other bus structure as can be appreciated.

Stored in the local memory359are both data and several components that are executable by the local processor356. In particular, stored in the local memory359and executable by the local processor356is the local meter controller, or metering device controller,403, and potentially other applications. Also, within the processor356is a local clock361from which timestamps169may be generated as described above. Alternatively, the local clock361may reside in the local memory359and is executable by the local processor356. In addition, an operating system may be stored in the local memory359and executable by the local processor356.

It is understood that there may be other applications that are stored in the local memory359and are executable by the local processors356as can be appreciated. Where any component discussed herein is implemented in the form of software, any one of a number of programming languages may be employed such as, for example, C, C++, C#, Objective C, Java, Javascript, Perl, PHP, Visual Basic, Python, Ruby, Delphi, Flash, or other programming languages.

The local meter controller403is stored in the local memory359and is executable by the local processor356. In this respect, the term “executable” means a program file that is in a form that can ultimately be run by the local processor356. Examples of executable programs may be a compiled program that can be translated into machine code in a format that can be loaded into a random access portion of the local memory359and run by the local processor356, source code that may be expressed in proper format such as object code that is capable of being loaded into a random access portion of the local memory359and executed by the local processor356, or source code that may be interpreted by another executable program to generate instructions in a random access portion of the local memory359to be executed by the local processor356, etc. An executable program may be stored in any portion or component of the local memory359including, for example, random access memory (RAM), read-only memory (ROM), hard drive, solid-state drive, USB flash drive, memory card, optical disc such as compact disc (CD) or digital versatile disc (DVD), floppy disk, magnetic tape, or other memory components.

The local memory359is defined herein as including both volatile and nonvolatile memory and data storage components. Volatile components are those that do not retain data values upon loss of power. Nonvolatile components are those that retain data upon a loss of power. Thus, the local memory359may comprise, for example, random access memory (RAM), read-only memory (ROM), hard disk drives, solid-state drives, USB flash drives, memory cards accessed via a memory card reader, floppy disks accessed via an associated floppy disk drive, optical discs accessed via an optical disc drive, magnetic tapes accessed via an appropriate tape drive, and/or other memory components, or a combination of any two or more of these memory components. In addition, the RAM may comprise, for example, static random access memory (SRAM), dynamic random access memory (DRAM), or magnetic random access memory (MRAM) and other such devices. The ROM may comprise, for example, a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or other like memory device.

Local processor356may also represent multiple processors356and the local memory359may represent multiple memories359that operate in parallel processing circuits, respectively. In such a case, the local interface363may be an appropriate network that facilitates communication between any two of the multiple processors356, between any local processor356and any of the local memories359, or between any two of the local memories359, etc. The local interface363may comprise additional systems designed to coordinate this communication, including, for example, performing load balancing. The processor356may be of electrical or of some other available construction.

The meter processing system353is configured to support multiple subsystem interfaces coupled through local interface363. The multiple interfaces can include but are not limited to sensing subsystem interfaces366,373,379,386,387,388that are any type including but not limited to digital or analog or combinations thereof as a matter of availability and design choice that facilitate meter processing system353communications and control of sensor subsystems340-344.

Electromagnetic field sensor subsystem340is in communications with and under the control of meter processing system353to facilitate sensing, measuring, and recording of data relating to but not limited to electromagnetic characteristics of a guided surface wave123or other type of electromagnetic emission as a matter of configuration and design choice. In one nonlimiting embodiment, the electromagnetic field sensor subsystem340includes but is not limited to a electromagnetic field meter interface366, an antenna396, and an electromagnetic field meter369therebetween. In one nonlimiting embodiment a signal condition circuit376can be connected between antenna396and the electromagnetic field meter369to facilitate signal conditioning that may be helpful or necessary for sensing and measuring low frequency electromagnetic signals. A signal conditioning interface373connected between the signal conditioning circuit376and the local interface363facilitates communication with and the configuration of the signal conditioning circuit376.

In another nonlimiting embodiment an antenna positioning subsystem341can be included to facilitate remote manipulation of antenna396where adjusting the physical orientation of the antenna396is desirable to optimize sensing and measuring electromagnetic fields. Antenna positioning subsystem341can include but is not limited to including an antenna position actuator399mechanically connected to antenna396to facilitate 180-degree horizontal rotational orientation and/or 90-degree positive/negative vertical elevation orientation of antenna396.

An antenna position controller383is coupled to or integrated within the antenna position actuator399as a matter of design choice, to directly control and instruct movements of the antenna position actuator399. The antenna position controller383in any design choice is coupled between the antenna position actuator399and the antenna positioning interface379to facilitate communication between the meter processing system353and the loop position controller383. Where antenna396is a single-axis multi-turn antenna, the antenna positioning subsystem341can facilitate orienting antenna396remotely. Where antenna396is instead a multi-axis antenna, such as a 3-axis multi-turn antenna configured to sense electromagnetic fields in x, y, and z directions, then antenna positioning subsystem341can remain present but inactive, or it may be removed from the metering device126altogether, as a matter of design choice.

Operationally within antenna positioning subsystem341, the antenna position controller383generates a position signal that is applied to the antenna position actuator399to cause antenna396to rotate horizontally along the x axis or elevate vertically along the y axis as instructed. The antenna position actuator399can provide a feedback signal to the antenna position controller383to indicate precise positioning of antenna396. In this manner, the antenna position controller383can know that antenna396is positioned optimally relative to guided surface wave123transmitted by guided surface waveguide probe122.

Note that the antenna position actuator399can include a compass or other orientation detection apparatus a reference from which the actual positioning of antenna396is determined. The antenna position actuator399may include various actuators such as stepper motors or other types of motors, gear systems, position sensors, and other components to facilitate movement of antenna396and provide feedback as to the current position of the same to the antenna position controller383. The antenna position actuator399working in conjunction with the antenna position controller383may position antenna396according to a desired positioning tolerance. The positioning tolerance of antenna396is specified to ensure that the electromagnetic field measurements173/176are accurate within a desired tolerance.

In one nonlimiting embodiment antenna396can be a single-axis passive multi-turn antenna. Antenna396is passive where there is no signal amplifier within the immediate antenna structure itself thereby further eliminating external noise and signal interference in applications where optimizing signal sensitivity is desirable for sensing low frequency and/or low energy signals. Antenna396is a single-axis antenna where it is configured only to sense one aspect of an electromagnetic field such as electric or magnetic field strength, and the optimal orientation of the single-axis antenna is orthogonal to the electromagnetic field being sensed. Antenna396is multi-turn where there are at least two wraps of an electrical conductor, such as insulated copper wire, within a nonferrous metal hoop (e.g., aluminum tubing). Multiple turns of wire within the hoop facilitate greater electromagnetic field sensitivity and signal output than a single turn within the hoop can produce. The diameter of the hoop and the number of turns of wire within the hoop are proportional to the frequency of the signal being sensed. According to one embodiment of the present disclosure, antenna396includes up to 8 turns of wire within an approximately 750-centimeter hoop for frequencies between approximately 100 kilohertz to 1710 kilohertz. More or fewer turns within a larger or smaller diameter hoop may be employed based on the sensitivity desired for higher or lower frequencies and/or the limits of diminishing returns with respect the practical size of the antenna. Lower frequencies down to 8 kilohertz can require 3 meter or larger hoops with tens of windings of wire therein to meet sensitivity sensing needs. The terminals of a passive multi-turn antenna396are coupled to electromagnetic field meter369at minimum but may be first coupled through signal conditioning circuit376as illustrated inFIG.7to amplify and/or filter the sensed signal.

FIG.11illustrates an alternative nonlimiting embodiment of antenna396configured as a passive multi-axis multi-turn antenna396-3x(hereafter 3-axis antenna396-3x). The passive, multi-turn, and hoop size of the 3-axis antenna396-3xcorrespond to the disclosure of similar features noted above for the passive single-axis multi-turn antenna396. The multiple axes aspect of 3-axis antenna396-3xis the integration of three passive single-axis multi-turn antennas configured as a single functioning receive antenna. The 3-axis antenna396-3xis comprised of an x-axis antenna397, a y-axis antenna398, and a z-axis antenna399each in a fixed position at 90 degrees from the other two. This 3-axis antenna396-3xconfiguration facilitates sensing the magnetic field strength of guided surface wave123regardless of the orientation of the collective antenna. The aggregate signal sensed by each of the three x, y, and z antennas is the signal that is passed through the signal conditioning circuit376for conditioning as needed and then measured by the electromagnetic field meter(s)369regardless of any one antenna's orientation relative to the transmission source.

When the 3-axis antenna396-3xis used as the antenna396for metering device126at a fixed location along the lossy conductive medium124, the antenna positioning subsystem341is not needed and can be eliminated from the fixed location metering devices126a-N altogether. Alternatively, the antenna positioning subsystem341can be rendered inactive if it remains present in the metering device126. There is no need to optimally orient the 3-axis antenna396-3xtoward the transmission source as there was with the single-axis antenna396that required orthogonal positioning relative to the transmission source for optimal performance.

Additional features and characteristics that distinguish the 3-axis antenna396-3xof the present disclosure from other 3-axis antennas that may be similar in appearance, include but are not limited to: 1) design features that collectively optimize the sensitivity of antenna396-3xto low frequency electromagnetic output of less than 1710 Kilohertz down to 1 Kilohertz emitted from a transmission source external to antenna396-3xin an uncontrolled field environment; 2) multiple windings of wire within shielded x, y, and z hoops to minimize the multitude of external natural and man-made electromagnetic noise that exists around a metering device126location that can otherwise interfere with sensing a low frequency target signal transmitted tens of kilometers to thousands of kilometers away from a metering device126location for frequencies from 100 kilohertz down to 1 kilohertz; 3) in one embodiment of the present disclosure up to eight windings of the conductor within each of the x, y, and z hoops of approximately 750 centimeters diameter to maximize sensitivity to an external low frequency target signal in an uncontrolled field environment; 5) a passive antenna configuration that is free of nearby electronic components that are not electrically isolated from the antenna hoops themselves; and 6) utilizing at least one spectrum analyzer rather than a volt meter as the electromagnetic field meter369within the electromagnetic field sensor subsystem340to facilitate trace measurements and sensed signals that are off the target frequency due to influences of conductivity and permittivity of the air and soil local to the metering device126.

The 3-axis antenna396-3xalso allows a metering device126to be configured for mobile deployment in a ground-based or airborne vehicle. Mobile deployment of at least one mobile metering device126may be desirable where there are none or very few operational metering devices126a-N available in fixed positions along the lossy conducting medium124relative to the guided surface waveguide probe122. Given any quantity or positioning of fixed position metering devices126a-N, the deployment of one or more metering devices126made mobile due to the 3-axis antenna396-3xsupplements the collected meter measurement data153with continuous data across potentially wide areas between fixed position metering devices126a-N.

In an alternative nonlimiting embodiment, a mobile metering device126can be used to traverse gaps between fixed position metering devices126a-N while providing continuous real-time sensing and measuring of the guided surface wave123while in motion. This continuous real-time sensing and measuring while in motion produces data locally stored in local records159and is synchronized with time stamps169in the same manner as disclosed with fixed position metering devices126a-N. Local records159are also transmitted from a mobile metering device126to the primary meter controller143via a wireless connection to network133in a manner similar to the counterpart fixed position metering devices126a-N. The weather sensor subsystem342of a mobile metering device126is also configured to continuously sense and measure weather and atmospheric conditions local to the mobile metering device126even while in motion. A global positioning system sensor395can provide meter location179data to coordinate with timestamps169associated with electromagnetic field measurements173/176and weather sensing data186.

Soil sigma subsystem343sensing and measurements can be estimated along the path of a mobile metering device126based on direct measurements collected by fixed position metering devices126a-N proximate to points along the path of the mobile metering device126. Alternatively, or in addition to estimates of soil sigma at any given point along the path of mobile metering device126, soil sigma data187can be supplemented with direct measurements collected intermittently or periodically at fixed locations along the path of mobile metering device126either by a third party as the conveying vehicle passes by, or by the driver of the conveying vehicle when stopped or at rest. By analyzing the moisture content or lack of moisture recorded in weather sensing data186along with an increasing record of direct measurements of soil sigma data187along the path of mobile metering device126a-N, an accurate mapping can be produced regarding the estimated conductivity and permittivity of soil along the path of at least one mobile metering device126. Mobile weather sensing data186and direct and/or estimated mobile soil sensing data187can be used to adjust and normalize raw electromagnetic field measurements173/176in view of the relative influence that conductivity and permittivity of air and soil has on the guided surface wave123along the path of mobile metering device126.

In another nonlimiting embodiment a weather sensing subsystem342can be included to facilitate sensing and measuring weather and atmospheric conditions local to the metering device126in a fixed location. The weather sensing subsystem342can include but is not limited to or required to include sensors each coupled to at least one weather sensor interface386for communication with the meter processing system353.

In another nonlimiting embodiment a soil sigma subsystem343can be included to facilitate sensing and measuring conductivity and permittivity of soil local to the fixed position of metering device126. The soil sigma sensor(s)394are each coupled to at least one soil sensor interface387for communication with the meter processing system353.

In another nonlimiting embodiment other sensing subsystems344can be included to facilitate sensing and measuring of other factors local to the metering device126. The other sensor(s)395are each coupled to at least one soil sensor interface388for communication with the meter processing system353.

The local meter controller403is executed by the processor356to implement the functions of the metering device126as will be described. In addition, various data resides in the memory359. Such data may include, for example, the configuration data196and the records159. Other executable systems may be stored on the memory359as is needed for the proper operation of the meter processing system353such as, for example, an operating system or other executable system. In addition, other data may be stored in the memory359in association with the operation of the local meter controller403as can be appreciated.

If the records159are stored in the memory359, then the metering device126includes buffering capability as described above, where the memory359acts as the buffer memory. The configuration data196is used to configure the operation of the metering device126as was described.

Given the foregoing description of the metering device126, next a general description of the operation of the same is set forth. The local meter controller403communicates with the primary meter controller143to synchronize the local clock361with the primary clock144and to obtain the configuration data196that is used to configure the operation of the metering device126. The synchronization of the local clock361with the primary clock144is performed in accordance with one of the approaches described above.

The configuration data196may specify a number of parameters for the operation of the metering device126. For example, the configuration data196may specify the operating frequency at which electromagnetic field measurements173/176are to be taken. Also, nature of an electromagnetic field measurement traces to be taken using the electromagnetic field meter369may be specified including the low frequency, high frequency, and center frequency of the traces to be taken. Also, the number of electromagnetic field measurements173/176that are to be taken between the low and high frequencies may be specified. The configuration data196may further specify the desired position of antenna396. The configuration data196may include other information as will be described.

Once the configuration data196is received, the metering device126is configured for operation. To this end, the electromagnetic field meter369is configured for operation by inputting the relevant parameters into the electromagnetic field meter369according to a predefined communications protocol of the electromagnetic field meter369. The range of frequencies that can be sensed by the metering device126is specified by the electromagnetic field meter369. According to one embodiment of the present disclosure, the electromagnetic field meter369is configured to generate electromagnetic field strength measurements173/176at frequencies from approximately 6 Kilohertz to 120 Kilohertz, for example, although other frequency ranges may be specified.

Alternatively, other ranges may be specified. In one embodiment, the electromagnetic field meter369is configured to generate electromagnetic field measurements173/176at or below 50 Kilohertz.

In some embodiments, each of the electromagnetic field meter369comprises a spectrum analyzer. The electromagnetic field meter369is configured to generate electric and magnetic field measurements173/176on 6 axes. To this end, the passive multi-turn antenna396is representative of multiple such antennas that may be coupled to the electromagnetic field meter369. In addition to loop antennas, linear antennas may also be coupled to the electromagnetic field meter369such that electric field measurements173may be taken in up to 6 directions. Thus, antenna396is representative of different antenna structures and types that may be employed with the electromagnetic field meter369.

The data configuration196may also include information used to specify the state of the components in the signal conditioning circuit376as will be described.

Once the metering device126has been fully configured based upon the configuration data196received from the primary meter controller143, the metering device126proceeds to take electromagnetic field strength measurements173/176at the direction of the primary meter controller143. When directed to do so, the metering device126generates magnetic and/or electric field strength measurements173/176across one or more axes. Such magnetic and/or electric field strength measurements173/176are included in a local record159along with other information based on readings from the sensors393and information from other sources.

Once a local record159is generated with the electromagnetic field strength measurement(s)173/176, the local record159is downloaded to the primary meter controller143to be stored in the server data store146. In this manner, the metering device126transmits the electromagnetic field strength measurement(s)173/176to a remote computing device comprising the primary computing environment127through the network133. In one embodiment, the metering device126generates a local record159with one or more electromagnetic field strength measurements173/176and sends the same to the primary meter controller143executed on the primary computing environment127in response to a request from the primary meter controller143. In another embodiment, the metering device126automatically generates a continuous stream of electromagnetic field strength measurements173/176at the direction of the primary meter controller143that are included in a corresponding number of local records159that are stored in the local memory359that acts as a data buffer. The metering device126intermittently or periodically downloads the buffered local records159upon request by the primary meter controller143executed on the primary computing environment127.

FIG.8illustrates a state diagram example of functionality implemented by a metering device according to various embodiments of the present disclosure. Operations among devices can proceed serially or in parallel according to various aspects of the present disclosure. It is understood that state diagram410is one example of the many different types of functional arrangements that may be employed to implement the operation of the local meter controller403as described herein. In addition, local meter controller403may include additional functionality not discussed herein. As an alternative, state diagram410may be viewed as depicting example steps of a monitoring method implemented in the meter processing system353in some embodiments to monitor operational status of metering devices that include at least one mobile metering device and at least one fixed position metering device, one or more metering device systems, and at least one measurement sensor subsystem under operational control of the plurality of metering devices, and to remotely request: activating or deactivating one or more of the metering devices, or one or more metering device systems or measurement sensor subsystems, under operational control of one of the plurality of metering devices; verifying a configuration of one or more of the metering devices, or one or more metering device system or measurement sensor subsystem, under operational control of one of the metering devices; configuring one or more of the metering devices, or one or more metering device system or measurement sensor subsystem, under operational control of one of the plurality of metering devices; and downloading the measurement data obtained by one or more measurement sensor subsystem of one or more of the metering devices.

From the start of operation in state413primary meter controller143is operational and configured for communications with each of the metering devices126a-N by way of network133. Where primary meter controller143determines that one or more of the metering devices126a-N requires initialization to begin operation, primary meter controller143sends initialization instructions to the respective one or more metering devices126a-N and operation continues at state415. As the local meter controller403of each of the one or more metering devices126a-N confirms that initialization is complete, operation returns to state413.

From state413primary meter controller143may determine the need for one or more of the metering devices126a-N and/or their respective sensor subsystems to be configured, primary meter control143sends configuration instructions to the respective one or more metering devices126a-N and respective ones of the local meter controller403proceed with configuration operations at state417. As each local meter controller403confirms that configuration operations are complete, operation returns at state413.

From state413primary meter controller143may determine the need for one or more of the metering devices126a-N to synchronize their local clock361, primary meter controller143sends synchronization instructions to the respective one or more metering devices126a-N and respective ones of the local meter controller403proceed with clock synchronization operations at state419. As each local meter controller403confirms that clock synchronization operations are complete, operation returns at state413.

From state413primary meter controller143may determine the need for one or more of the sensor subsystems of one or more metering devices126a-N to begin sensor measurements, primary meter controller143sends commence measurement instructions to the respective one or more metering devices126a-N and respective ones of the local meter controller403proceeds to start the respective sensor subsystems at state421. Each local meter controller403confirms with primary meter controller143that sensor subsystem measurements are initiated, and measurement storing is initiated in local memory, and respective metering device126measuring/storing operations proceed in state421in parallel with primary meter controller143continuing activities in state413. Among further operations by primary meter controller143in state413is to request ongoing or periodic downloads of local records159from one or more local meter controllers403. Further, primary meter controller143can at any time initiate parallel instructions for any one or more of the metering devices126a-N to reconfigure its operating parameters or sensor subsystem configurations in state417, or request further clock synchronization at state419, and the like.

From state413primary meter controller143may determine the need for one or more of the metering devices126a-N to suspend or shut down sensor measurements or one or more sensor subsystems. Primary meter controller143sends suspend or shutdown instructions to the respective one or more metering devices126a-N, and respective ones of the local meter controller403proceed with suspension and/or shutdown operations at state423. As each local meter controller403confirms that suspension and/or shutdown operations are complete, operation returns at state413.

Similarly, the primary meter controller143may determine the need for one or more of the metering devices126a-N to idle all systems and subsystems or to shut down entirely. Primary meter controller143sends idle or shutdown instructions to the respective one or more metering devices126a-N, and respective ones of the local meter controller403proceed idle all systems and subsystems, or to shut down operations entirely at state425. As each local meter controller403confirms that idling is achieved, the respective metering devices proceed to idle at state425until further instruction from the primary meter controller143(e.g., new initialization or configuration instructions). For respective metering devices126a-N instructed to shut down entirely, processing ends at state425.

FIG.9illustrates an example of the configuration data196for metering devices126a-N to configure the various components of such metering devices126a-N and their respective sensor subsystems340-344for operation. The configuration data196is input by a user into the primary meter controller143for delivery to metering devices126a-N for initialization and configuration.

The configuration data196includes but is not limited to settings for all aspects of a metering device126and all sensor subsystems340-344. Examples include a “Name of Test” field to identify a specific test run of a given guided surface waveguide probe122. The “Name of Test” field may include, for example, a frequency of operation and/or a date upon which the test is to occur, and any other identifying information desired.

Configuration data196can further include a setting for a center frequency and a span of an electromagnetic field measurement trace to be obtained when electromagnetic field measurements173/176are generated. Alternatively, the electromagnetic field measurement trace may be specified with a center frequency along with low and high frequencies, or the electromagnetic field measurement trace may be specified in some other manner. The configuration data further includes a “Resolution Bandwidth” that indicates the selectivity and noise sensitivity of the electromagnetic field meter369in Hertz.

Further electromagnetic fields in the configuration data196include a reference level and units of measurement. The reference level identifies the amplitude threshold of the electromagnetic field meter369. The units of measurement indicate the units of the electromagnetic field measurements173/176such as millivolts per meter (mV/m) or other units. The configuration data196also includes antenna position information that may be expressed as degrees from a fixed reference point such as degrees from North, where North may be determined from an electronic compass as described above. The configuration data196may further specify the state of various components such as amplifiers (preamps), switches, filter circuits, attenuation circuitry, and other components in the signal conditioning circuit376(FIG.7). In addition, other parameters and settings for other sensor subsystems340-344may be specified in the configuration data196.

FIG.10is a schematic diagram of one example of the signal conditioning circuit376according to various embodiments of the present disclosure. The signal conditioning circuit376facilitates both the electronic filtering of signals from antenna396and the amplification of such signals before they are applied to the electromagnetic field meter369.

The signal conditioning circuit376includes at least two amplifiers, denoted herein as first stage amplifier473aand second stage amplifier473b. The signal conditioning circuit376also includes four radio frequency (RF) switches organized into two pairs denoted herein as the RF switches S1A, S1B, S2A, and S2B. The first and second stage amplifiers473aand473bmay comprise, for example, RF amplifiers or other types of amplifiers. The first and second stage amplifiers473aand473bmay also be configured as active filters to reduce noise. In one example, the first and second stage amplifiers473aand473bmay each comprise, for example, a wideband low noise Amplifier model HD24540 manufactured by HD Communications Corporation of Holbrook, New York.

The signal conditioning circuit376further includes impedance match circuitry476that provides for impedance matching as can be appreciated. The impedance match circuitry476is coupled to the signal input of the first stage amplifier473aas will be described. The signal conditioning circuit376further includes a filter circuit486that eliminates unwanted spurious signals from the desired signal received from antenna396as will be described. The local meter controller403causes the signal conditioning interface373to send one or more signals to the signal conditioning circuit376that control the operation of the first and second stage amplifiers473aand473b, the RF switches S1A/S1B/S2A/S2B, the filter circuit486, and potentially other components as will be described. In this manner, the local meter controller403controls the operation of the components in the signal conditioning circuit376.

The input signal from antenna396is coupled to the filter circuit486. The filter circuit486receives a control input from local meter controller403through signal conditioning interface373. This control input configures the operation of the filter circuit486. For example, filter circuit486may include a plurality of different low pass filters, where each low pass filter has a different cutoff frequency. In one embodiment, the control input from the signal conditioning interface373selects one of such low pass filters to be placed in the circuit pathway so that the desired low frequencies pass through the filter circuit486and high frequencies about the cutoff point are dissipated accordingly.

Filter circuit486may also include other types of filters such as band pass filters, notch filters, or other types of filters. Such filters may be static in nature or configurable to provide for various filtering options depending on the frequency of the transmitted signals that are to be acquired by antenna396. The ultimate operation of the filter circuit486may be controlled by control signals generated by the signal conditioning interface373as directed by the local meter controller403. Such control signal is applied to the filter circuit486to specify the desired filtering to be performed by the filter circuit486. The signal output from the filter circuit486is applied to an input of the RF switch S1A as shown. Alternatively, the filter circuit486may not be employed at all. In such case, the signal output of antenna396may be applied directly to the input of the RF switch S1A.

Each of the RF switches S1A, S1B, S2A, and S2B include an A node and a B node as shown. When the RF switch S1A is in the A state, the common node C of the RF switch S1A is coupled to the A node, thereby applying the input from antenna396to an input of impedance match circuitry476. The output of the impedance match circuitry476is coupled to a signal input of the first stage amplifier473a. When in the B state, the common node C of the RF switch S1A is applied to node B of the RF switch S1A. In this manner, the first stage amplifier473ais bypassed by bypass conductor479a.

The output of the first stage amplifier473ais applied to the A node of the RF switch S1B. When in the A state, the A node of the RF switch S1B is coupled to a common node C of the RF switch S1B. When in the B state, the B node of the RF switch S1B is coupled to the common node C of the RF switch S1B. The common node C of the RF switch S1B is coupled to a common node C of the RF switch S2A as shown.

According to one embodiment, the RF switches S1A and S1B are both placed into either the A state or the B state simultaneously. When both RF switches S1A and S1B are in the A state, the input signal from antenna396is applied to the impedance match circuitry476and the first stage amplifier473a. When both RF switches S1A and S1B are in the B state, the input signal from antenna396is routed around the impedance match circuitry476and the first stage amplifier473aby way of the bypass conductor479a.

When in the A state, the common node C of the RF switch S2A is coupled to the A node of RF switch S2A which, in turn, is coupled to a signal input of the RF switch S2A. When in the B state the common node C of the RF switch S2A is coupled to the B node of RF switch S2A which, in turn, is coupled to bypass conductor479bthat facilitates bypassing the second stage amplifier473b.

The signal output of the second stage amplifier473bis coupled to an A node of the RF switch S2B. The bypass conductor479bis coupled to the B node of the RF switch S2B. When in the A state, node A of the RF switch S2B is coupled to the common node C of the RF switch S2B, thereby coupling the signal output of the second stage amplifier473bto the electromagnetic field meter369that is coupled to the common node C of the RF switch S2B. When in the B state, node B of the RF switch S2B is coupled to the common node C of the RF switch S2B, thereby coupling the bypass conductor479bto the electromagnetic field meter369coupled to the common node C of the RF switch S2B.

According to one embodiment, the RF switches S2A and S2B are both placed into either the A state or the B state simultaneously. When both RF switches S2A and S2B are in the A state, the input signal at common node C of the RF switch S2A is applied to the second stage amplifier473b. When both RF switches S2A and S2B are in the B state, the input signal at common node C of the RF switch S2A is routed around the second stage amplifier473bby way of the bypass conductor479b.

According to one embodiment, the signal conditioning circuit376can be placed in one of three states for the operation of the amplifiers included therein. As an additional alternative, the local meter controller403may implement an initial configuration routine with respect to the signal conditioning circuit376. Specifically, a signal may be transmitted from a guided surface waveguide probe122and pre-amplifiers in the signal conditioning circuit376may be switched in or out of the circuit until an acceptable signal is input to the electromagnetic field meter369.

The operational states of signal conditioning circuit376are controlled by local meter controller403that sends control signals through a control signal bus489coupled to the signal conditioning interface373.

In a first state, the signal received from antenna396is routed directly to the electromagnetic field meter369without amplification by either one of the first or second stage amplifiers473a-473b. The local meter controller403causes RF switches S1A and S1B associated with the first stage amplifier473ato be placed in the B state. The RF switches S2A and S2B associated with the second stage amplifier473bare also placed in the B state. Also, the first and second stage amplifiers473are disabled. In this configuration, the signal received from antenna396is routed through the filter circuit486, if any, and directed to the electromagnetic field meter369, bypassing both the first and second stage amplifiers473a-473b. In this respect, the RF switches S1A, S1B, S2A, and S2B route the signal received from antenna396through bypass conductors479a-479b, thereby coupling antenna396directly to the output of the signal conditioning circuit376to electromagnetic field meter369.

The bypass conductors479aand479bare labeled “bypass conductors” because the amplifiers473a-473bare bypassed accordingly. In the first state, the amplifiers473a-473bare electrically isolated from the signal path leading from antenna396to electromagnetic field meter369.

In a second state, the signal received from antenna396is routed through the impedance match circuitry476and the first stage amplifier473awhile bypassing the second stage amplifier473b. The signal from antenna396is amplified by one of the first and second stage amplifiers473a/473b. The local meter controller403causes RF switches S1A-S1B to be placed in the A state and causing RF switches S2A-S2B to be placed in the B state.

In this second state, the signal from antenna396is routed through the filter circuit486, if any, to an input of the impedance match circuitry476and first stage amplifier473a. The output of the first stage amplifier473ais routed directly to the electromagnetic field meter369via bypass conductor479a. The first stage amplifier473ais enabled and the second amplifier473bis disabled. Because RF switches S2A-S2B are in the B state, the second stage amplifier473bis electrically isolated from the circuit.

In a third state, the signal received from antenna396is routed through the impedance match circuitry476and both amplifiers473a-473bfor maximum amplification and/or filtering of the signal. The local meter controller403causes all of the RF switches S1A, S1B, S2A and S2B to be placed in the A state so the signal from antenna396is routed through the filter circuit486, if any, and through the impedance match circuitry476to then both amplifiers473a-473bin series and output directly to electromagnetic field meter369. The first and second stage amplifiers473aand473bare both enabled.

With respect to the foregoing, a phrase, such as “at least one of X, Y, or Z,” unless specifically stated otherwise, is to be understood with the context as used in general to present that an item, term, etc., can be either X, Y, or Z, or any combination thereof (e.g., X, Y, and/or Z). Similarly, “at least one of X, Y, and Z,” unless specifically stated otherwise, is to be understood to present that an item, term, etc., can be either X, Y, and Z, or any combination thereof (e.g., X, Y, and/or Z). Thus, as used herein, such phrases are not generally intended to, and should not, imply that certain embodiments require at least one of either X, Y, or Z to be present, but not, for example, one X and one Y. Further, such phrases should not imply that certain embodiments require each of at least one of X, at least one of Y, and at least one of Z to be present.

Although embodiments have been described herein in detail, the descriptions are by way of example. The features of the embodiments described herein are representative and, in alternative embodiments, certain features and elements may be added or omitted. Additionally, modifications to aspects of the embodiments described herein may be made by those skilled in the art without departing from the spirit and scope of the present disclosure defined in the following claims, the scope of which are to be accorded the broadest interpretation so as to encompass modifications and equivalent structures.