Multimodal radio wave imaging system and method

Abstract

A multimodal subsurface imaging unit includes a wideband transceiver with a wide band radio frequency signal generator operable to generate radio frequency signals within a wide band. The multimodal subsurface imaging unit includes a plurality of sets of imaging antennas, including a high frequency set, a low frequency set, and a time domain set. The multimodal subsurface imaging unit includes a switching network communicatively coupled to the wideband radio transceiver and to each of the plurality of antennas, and a control unit. The control unit is operable to control operations of the wideband radio transceiver and the switching network and receive echo signals from the plurality of sets of radio imaging antennas based on echoes of the radio frequency signals and provide the echo signals to a storage device, wherein the echo signals are suitable for analysis for feature extraction.

Description

TITLE: MULTIMODAL RADIO WAVE IMAGING SYSTEM AND METHODFIELD

[0001] The description related generally to radio wave imaging, particularly to multimodal imaging.BACKGROUND

[0002] United States Patent App. Pub. No. 2024 / 0008389 to Anderson et al. (“Anderson”) purports to disclose systems, methods and devices for using machine learning to optimize crop residue management. Anderson purports to disclose that operations of such methods include receiving, using a processing circuit and from multiple of sensors, crop residue data of a surface of a soil area, receiving, into the processing circuit and from a location sensor, geographic location data that corresponds to the crop residue data and generating multizone tillage data that is based on the crop residue data and that corresponds to a plurality of zones that are defined in the soil area.SUMMARY

[0003] The following summary is intended to introduce the reader to various aspects of the applicant’s teaching, but not to define any invention.

[0004] In accordance with some aspects, there is provided a multimodal subsurface imaging unit to be removably mounted to a carrier vehicle, the multimodal subsurface imaging unit comprising: a wideband transceiver, including a wide band radio frequency signal generator operable to generate radio frequency signals within a wide band, a plurality of sets of imaging antennas including a set of high frequency antennas, a set of low frequency antennas, and a set of time domain antennas, each set of radio imaging antennas including at least one transmit antenna and at least one receive antenna, a switching network communicatively coupled to the wideband radio transceiver and to each of the plurality of antennas to selectively couple the wideband radio transceiver to a selected set or selected sets of the plurality of sets of radio imaging antennas to pass the radio frequency signals to theselected set or sets of radio imaging antennas, and a control unit communicatively coupled to the wideband radio transceiver and the switching network, the control unit including at least one processor and at least one data storage device and operable to control operations of the wideband radio transceiver and the switching network and receive echo signals from the plurality of sets of radio imaging antennas based on echoes of the radio frequency signals and provide the echo signals to a storage device, wherein the echo signals are suitable for analysis for feature extraction.

[0005] In some examples, the control unit further includes an analog to digital converter, a digital to analog converter, and a field programmable gate array operable to capture low frequency data.

[0006] In some examples, the control unit is communicatively coupled to the plurality of sets of radio imaging antennas via the wideband radio transceiver.

[0007] In some examples, the unit further comprises a communication interface communicatively coupled to the control unit for providing the echo signals externally.

[0008] In some examples, the communication interface includes a wireless communication transmitter operable to transmit the echo signals to a remote location in real time.

[0009] In some examples, the wide band from which the wide band radio frequency signal generator is operable to generate the radio frequency signals includes a range from 10 kilohertz to 3 gigahertz.

[0010] In accordance with some aspects, there is provided a multimodal subsurface imaging system, comprising: a wideband radio transceiver, including a wide band radio frequency signal generator operable to generate radio frequency signals from a wide band, a plurality of sets of radio imaging antennas including a set of high frequency antennas for continuous ground penetrating radar data collection, a set of low frequency antennas for magnetic induction data collection, and a set of time domain antennas for pulsed radardata collection, a switching network communicatively coupled to the wideband radio transceiver and to each of the plurality of antennas to selectively couple the wideband radio transceiver to a selected set or sets of the plurality of sets of radio imaging antennas to pass the radio frequency signals to the selected set or sets of radio imaging antennas, and at least one processor communicatively coupled to the wideband radio transceiver, the switching network, and the plurality of sets of radio imaging antennas to control operations thereof and receive echo signals based on echoes of the radio frequency signals.

[0011] In some examples, the system further comprises, between the at least one processor and the plurality of sets of radio imaging antennas, an analog to digital converter, a digital to analog converter, and a field programmable gate array operable to capture low frequency data.

[0012] I n some examples, the at least one processor is communicatively coupled to the plurality of sets of radio imaging antennas via the wideband radio transceiver.

[0013] In some examples, the system further comprises a communication interface communicatively coupled to the control unit.

[0014] In some examples, the communication interface includes a wireless communication transmitter operable to transmit the echo signals in real time for remote processing.

[0015] In some examples, the system further comprises a location unit integrated with the multimodal radio wave imaging unit for providing location information.

[0016] In some examples, the wide band from which the wide band radio frequency signal generator is operable to generate the radio frequency signals includes a range from 10 kilohertz to 3 gigahertz.

[0017] In some examples, the system further comprises a vehicle carrying the plurality of sets of radio imaging antennas.

[0018] In some examples, the at least one processor is further operable to process the echo signals to generate output information based on one or more selected modalities and excluding the others.

[0019] In some examples, the output information includes one or more of the following: rock presence in soil based on the pulsed radar data and / or the continuous wave ground penetrating radar data; electric conductivity, moisture amount, and / or compaction based on the magnetic induction data, compaction based on the pulsed radar data; soil layers based on the pulsed radar data; tuber mapping based on the continuous wave radar data; tuber mapping based on the continuous wave radar data, the pulsed radar data, and the magnetic induction data; spoilage in a grain pile based on the pulsed radar data; spoilage in a grain pile based on the pulsed radar data and the continuous wave radar data; grain volumetric mapping and moisture layers in the grain pile based on the pulsed radar data, the continuous wave radar data, and the magnetic induction data; soil carbon amount; and elevation mapping based on the pulsed radar data.

[0020] In accordance with some aspects, there is provided a subsurface sensing method, comprising: moving a vehicle over a target body, the vehicle carrying a multimodal imaging module; generating radio frequency signals; and collecting multimodal imaging data of the target surface by transmitting, using each of a plurality of sets of radio imaging antennas of the multimodal imaging module, the radio frequency signals towards the target material and acquiring echoes of the radio frequency signals, and wherein the plurality of sets of radio imaging antennas include at least three discrete sets of antennas including continuous wave magnetic induction antennas, continuous wave ground penetrating radar antennas, and pulsed radar antennas such that the multimodal imaging data includes magnetic induction data, continuous wave ground penetrating radar data, and pulsed radar data.

[0021] In some examples, the continuous wave magnetic induction antennas operate between 10 kilohertz and 40 kilohertz, the continuous wave ground penetrating radar antennas operate between 600 megahertz and 1gigahertz, and the pulsed radar antennas operate with pulse transmissions spaced apart between 0.5 nanoseconds and 5 nanoseconds.

[0022] In some examples, the vehicle is a drone, a sprayer, a seeder, or a tractor.

[0023] In some examples, the target body comprises soil and rocks, and the method further comprises detecting the rocks in the soil using the pulsed radar data and / or the continuous wave ground penetrating radar data; the target body includes a layer of earth, and the method further comprises detecting electric conductivity, moisture amount, and / or compaction using the magnetic induction data and / or the pulsed radar data; the target body includes soil layers, and the method further comprises detecting the soil layers using the pulsed radar data; the target body includes buried tubers, and the method further comprises detecting the buried tubers using continuous wave ground penetrating radar data; the target body is an outdoor grain pile; the target body includes a grain pile, and the method further comprises detecting an area of concern in the grain pile using the pulsed radar data; or the target body includes a surface with varying elevation, and the method further comprises detecting an elevation map using the pulsed radar data.BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings included herewith are for illustrating various examples of articles, methods, and apparatuses of the present specification and are not intended to limit the scope of what is taught in any way. In the drawings:

[0025] FIG. 1 is a schematic diagram of a multimodal subsurface imaging unit;

[0026] FIG. 2 is a schematic diagram of a multimodal subsurface imaging system;

[0027] FIG. 3 is an expanded schematic view of a configurable pulsed radar module of the system of FIG. 2; and

[0028] FIG. 4 is a flow chart of a subsurface imaging method.DETAILED DESCRIPTION

[0029] Various apparatuses or processes will be described below to provide an example of an embodiment of each claimed invention. No example described below limits any claimed invention and any claimed invention may cover processes or apparatuses that differ from those described below. The claimed inventions are not limited to apparatuses or processes having all of the features of any one apparatus or process described below or to features common to multiple or all of the apparatuses or processes described below. It is possible that an apparatus or process described below is not an embodiment of any claimed invention. Any invention disclosed in an apparatus or process described below that is not claimed in this document may be the subject matter of another protective instrument, for example, a continuing patent application, and the applicants, inventors or owners do not intend to abandon, disclaim or dedicate to the public any such invention by its disclosure in this document.

[0030] Furthermore, it will be appreciated that for simplicity and clarity of illustration, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements. It should be noted that the term “coupled” used herein indicates that two elements can be directly coupled to one another or coupled to one another through one or more intermediate elements. The term “directly coupled” used herein indicates that two elements are coupled to one another without intermediate elements.

[0031] Referring to Figure 1 , an example embodiment of a multimodal subsurface imaging unit 100 is illustrated. In use, the multimodal subsurface imaging unit 100 acquires data from surface and subsurface features of a target body, such as surface and subsurface features of the soil. The multimodal subsurface imaging unit 100 acquires data noninvasively, and can be integrated into or mounted to a vehicle (e.g., a sprayer, seeder, tractor, or drone). Fusion of data from a plurality of modalities provides more detail about the target body and its properties. Where the target body is a complex media (e.g., soil), combining data from different modalities using fusion based algorithms can best characters features and increase accuracy. The multimodalsubsurface imaging unit 100 is operable to collect data across a plurality of modalities simultaneously by including a plurality of sets 102 of transmitter and receiver antennas. The exemplary sets 102 each include one or more transmitter antenna 104 and one or more receiver antenna 106.

[0032] In some embodiments, data is analyzed by artificial intelligence algorithms and / or optimization algorithms. In some embodiments, data analysis is used to provide farmers with information about subsurface features, such as physical properties of soil and / or physical properties of vegetation roots. In some embodiments, data analysis extracts information about soil carbon, moisture content, soil or root type, tuber size, and / or tuber density.

[0033] In some embodiments, the unit 100 is selectively operable to collect data across all of the modalities simultaneously or to collect data across only a subset of the modalities, the subset being one or more modality of the plurality of modalities. Choosing a subset of modalities to operate may speed up data collection, reduce operating costs such as energy requirements, and / or reduce signal interference, e.g., by leaving one or more sets of antennas unexcited during operation of the unit 100. To speed up data collection process and / or reduce interference between modalities, in some embodiments the apparatus is operated with reduced or eliminated over-lapping frequency bands. To speed up data collection, the size of data collected at each instant may be reduced (e.g., along with FPGA-based data processing to clean up data that is being acquired). Alternatively, in some embodiments, the unit 100 is only operable to collect data across all of the plurality of modalities simultaneously. Operating across all modalities simultaneously may represent a minor (e.g., negligible) increase in operating costs and provide considerably more data for analysis. Removing the option of selecting modalities may reduce the operational complexity of the unit and / or the need for an operator to know which modalities are required for the type of analysis they desire or may desire later on.

[0034] In some embodiments, the unit 100 is operable to collect data across at least two modalities selected from the list of magnetic induction,continuous wave ground penetrating radar, and pulsed radar. In some embodiments, the unit 100 includes at least two sets of antennas including a set for each of at least two from the list of continuous wave magnetic induction antennas, continuous wave ground penetrating radar antennas, and pulsed radar antennas. For example, vivaldi antennas may be used, such as those from Rfspace™. In some examples, the TSA800™ antennas from Rfspace™ may be used. The example unit 100 of Figure 1 includes a set of high frequency antennas 102a, a set of low frequency antennas 102b, and a set of time domain antennas 102c.

[0035] The set of high frequency antennas 102a are operable to use in ground penetrating radar data collection. The ground penetrating radar may be continuous wave ground penetrating radar (e.g., frequency modulated continuous wave radar). In some embodiments, the ground penetrating radar antennas operate between 600 megahertz and 1 gigahertz, which the inventor has found to be optimal in some embodiments. The set of low frequency antennas 102b are operable for magnetic induction data collection. In some embodiments, the continuous wave magnetic induction antennas operate between 10 kilohertz and 30 kilohertz, which the inventor has found to be optimal in some embodiments. The set of time domain antennas 102c are operable for pulsed radar data collection. In some embodiments, the pulsed radar antennas operate with a pulse width between 0.1 nanoseconds and 10 nanoseconds, which the inventor has found to be an optimal range in some embodiments. Narrower pulse width gives higher resolution, and wider pulse width gives deeper penetration. Narrower width may be used for acquiring near- surface data (e.g., the first couple of feet), and wider pulse widths may be used for further depths. In some embodiments, the pulse width can be selected by a user (e.g., via a user interface), such as selected from a predetermined range or independently selected by the user. In some embodiments, the time domain antennas operate in the same or a similar frequency range as the high frequency antennas 102a (e.g., between 600 megahertz and 1 gigahertz). In some embodiments, the time domain antennas operate between 700megahertz and 3 gigahertz, which the inventor has found to be optimal in some embodiments. The lower end of the band helps with penetration and the higher end helps with resolution. The depth of penetration depends on many parameters such as soil moisture and texture, but, for example, the depth of penetration at 700 megahertz may be about 2 feet compared to about 1 inch at 3 gigahertz. Resolution depends on many parameters such as algorithm selection, but, for example, the smallest object resolved at 700 megahertz may be about 8 inches compared to about 2 inches at 3 gigahertz. In some embodiments, all frequencies are used together and data is gathered for the whole range. In some embodiments, the multimodal imaging data includes magnetic induction data, continuous wave ground penetrating radar data, and pulsed radar data.

[0036] The unit 100 includes a wideband transceiver 110. The wideband transceiver 110 includes a wideband frequency signal generator 112 operable to generate radio frequency signals selected from anywhere within a wide band. As an example, the wideband transceiver may be the AD9363™ from Analog Devices™. As another example, a system level transceiver may be the LimeSDR XTRX™ using LMS7002M RF transceiver IC™ (e.g., due to a wide instantaneous bandwidth and a low frequency end). As another example, the integrated software defined radio of LMS7002M™ may be used (e.g., due to a desirable communication interface, which can be a bottleneck for data movement thus increasing acquisition time). In some embodiments, the wide band from which the wide band radio frequency signal generator is operable to generate the radio frequency signals is a band from a few kilohertz to a few gigahertz. In some embodiments, the wide band is from 5 kilohertz to 5 gigahertz, from 8 kilohertz to 4 gigahertz, or from 10 kilohertz to 3 gigahertz.

[0037] In some embodiments, the transceiver 110 includes a mixer 114, a filter 116, and / or an amplification module 118. In some embodiments, the transceiver 110 includes at least one mixer 114, at least one filter 116, and / or at least one amplification module 118 for each of the transmit and receive paths.

[0038] The multimodal subsurface imaging unit 100 includes a switching network 120. The switching network 120 is communicatively coupled to the wideband radio transceiver 110 and to each of the sets of antennas 102 to selectively couple the wideband radio transceiver 110 to a selected set or sets of the plurality of sets 102 of radio imaging antennas to pass radio frequency signals from the transceiver 110 to the selected set or sets 102.

[0039] The multimodal subsurface imaging unit 100 includes a control unit 130. The control unit 130 is communicatively coupled to the wideband radio transceiver 110 and the switching network 120. In some embodiments, the control unit 130 is communicatively coupled to the plurality of sets 102 of radio imaging antennas via the wideband radio transceiver 110. The control unit 130 includes at least one processor 132 and at least one data storage device 134. The control unit 130 is operable to control operations of the wideband radio transceiver 110 and the switching network 120 and receive echo signals from the plurality of sets 102 of radio imaging antennas based on echoes of the radio frequency signals. In some embodiments, the control unit is implemented by a small computer. In some embodiments, the small computer is a single-board computer. In some exmaples, the control unit is implemented by a Raspberry PjTM

[0040] The unit 100 includes a data acquisition module 140. The data acquisition unit 140 may be implemented as part of the control unit 130 (e.g., on a common computer board) or physically discrete therefrom. The data acquisition unit 140 includes an analog to digital converter 142, a digital to analog converter 144, and / or a field programmable gate array 146 operable to capture low frequency data.

[0041] In some embodiments, the multimodal subsurface imaging unit 100 is built from radio wave components. Alternatively, in some embodiments, a software defined radio 148 is used to implement most of the multimodal subsurface imaging unit 100. In some embodiments, the software defined radio 148 is used to implement at least the data acquisition module 140 and wideband transceiver 110. In some examples, the multimodal subsurfaceimaging unit 100 comprises a single board computer implementing the control unit 130, a software defined radio 148 implementing the data acquisition unit 140 and the wideband transceiver 110.

[0042] The echo signals may be stored locally, e.g., on storage device 134. Alternatively, or additionally, the echo signals may be transmitted to a remote device 160. The remote device 160 is a storage and / or analysis device. In some embodiments, the remote device 160 includes one or more processors and / or one or more data storage facilities, in a common location or distributed. In some embodiments, the unit 100 includes a communication interface 150 for providing the echo signals externally. The communication interface 150 is communicatively coupled to the control unit 130 to receive transmission instructions therefrom. The communication interface 150 may be implemented as part of the control unit 130 (e.g., on a common computer board) or physically discrete therefrom. The communication interface 150 may receive the echo signals via the control unit 130. Alternatively, in some embodiments, the communication interface 150 is also communicatively coupled directly to the data acquisition unit 140 to receive the echo signals directly therefrom. The communication interface 150 includes a wireless communication transmitter 152 operable to transmit the echo signals to a remote location. In some embodiments, the transmitter 152 is operable to transmit the echo signals in real time.

[0043] In some embodiments, the unit 100 includes an integrated location unit 170 for providing location information. The integrated location unit 170 may be, e.g., a Global Positioning System™ unit. The integrated location unit 170 is communicatively coupled to the control unit 130 and / or the data acquisition unit 140 to receive control instructions and / or provide the location information. In some embodiments, the integrated location unit 170 is directly coupled to the data acquisition unit 140 to provide the location information directly to the data acquisition unit 140 for association with the echo signals.

[0044] The unit 100 may be integrated with a carrier vehicle. A unit 100 may be at least partially within the housing of the vehicle and incorporate oneor more components of the vehicle. In some examples, an integrated unit 100 is connected to the location unit of the vehicle, such as a Global Positioning System™ unit of a drone or other vehicle.

[0045] Alternatively, the unit 100 may be a stand-alone unit to be mounted to a carrier vehicle. The example unit 100 is to be removably mounted to a carrier vehicle 204. The example module 100 includes a housing 200 and a mount 202. The housing 200 encloses at least the processor of the unit, and the example housing 200 encloses multiple components. The mount 202 couples the housing to the vehicle. Any suitable mount 202 may be used, such as a stand-off mount which holds the housing away from the vehicle or a flush mount which holds a wall of the housing against the vehicle. The mount 202 may incorporate any suitable fastener to releasably secure the vehicle and housing together, such as a threaded fastener, a magnetic fastener, or a snap- fit fastener. In some embodiments, the mount 202 is a motorized gimbal (e.g., to hold the apparatus stationary and reduce un-necessary motion). It will be appreciated that the housing 200 may alternatively be directly mounted to the vehicle without the mount 202.

[0046] In some embodiments, at least one analysis processor, such as a processor 132 of the control unit 130 and / or a processor of the remote device 160, is operable to process the echo signals to generate output information. In some examples, the output information is based on processing one or more selected modalities and excluding one or more other modalities of the plurality of modalities. In some embodiments, data from one modality is used to provide a desired output information. In some embodiments, data from two or more modalities is fused using fusion based algorithms and analysis to provide the desired output information.

[0047] In some embodiments, fusion includes data from the time domain imaging system combined with the induction data to both locate inhomogeneities within the soil and characterize the features of the soil such as the soil moisture content or the carbon amount. The inventor has found that, in some embodiments, time domain data is useful for finding the range to aninhomogeneity, but incapable of providing direct information about the soil characteristics, while induction is useful in recovering the properties of the soil such as soil moisture, salinity and compaction amount. The inventor has found that, in some embodiments, if soil is wet and has inhomogeneities such as a rock, the calculations from the induction system provides information about the combinational effect of the soil and the rock and cannot distinguish the two from one another. The inventor has found that, in some embodiments, fusing the data in such a scenario improves the characterization of the soil properties.

[0048] In some embodiments, the output information includes rock presence in soil based on the pulsed radar data and / or the frequency modulated continuous wave radar data. Rock presence information may used to, e.g., avoid damage to farm equipment. In some embodiments, rock presence information is determined in real time for the soil ahead of the vehicle in a direction of travel, e.g., to provide information about rock presence before the vehicle hits the rock. In use, rock presence information may be used to adjust the operation of the vehicle, such as by slowing the vehicle, changing the path of the vehicle (e.g., to avoid a rock), and / or raising or lowering equipment (e.g., lowering a rock picker to meet a rock or raising a plow blade to avoid a rock). Rock presence information may be used in variable rolling of a field.

[0049] Rocks below the soil surface or very close to the surface can get caught in equipment such as tillers and combines if not detected early on. The inventor has found that, in some embodiments, pulsed radar (time domain radar) alone or combined with FMCW radar can help find the buried rocks allowing users (e.g., farmers) to plan their operation in a way to avoid potential equipment damage. Additionally, users can use such information in planning how they role their field, and which areas of their fields have more rocks than manageable to avoid those areas completely. This information can be provided to the users in real time as they are moving across the field. The data can be integrated into equipment control systems of equipment that may be damaged (e.g., tillers and combines) to ensure smooth data integration and use. In someembodiments, soil may be scanned for rocks prior to determining a value of a piece of land (e.g., prior to a user deciding whether to buy the land).

[0050] In some embodiments, the output information includes electric conductivity, moisture amount, and / or compaction based on the magnetic induction data. In some embodiments, the output information includes compaction based on the pulsed radar data.

[0051] In some embodiments, the output information includes soil layers based on the pulsed radar data. Soil layers are the thickness of different layers such as an organic matter map or a water table map.

[0052] In some embodiments, the output information includes tuber mapping (e.g., potatoes or sugar beets) based on the frequency modulated continuous wave radar data. In some embodiments, the output information includes tuber mapping based on the frequency modulated continuous wave radar data, the pulsed radar data, and the magnetic induction data.

[0053] In some embodiments, the target body is a grain pile. In some embodiments, the grain pile is an outdoor grain pile (i.e. , not stored in a bin or other housing). In some embodiments, the output information includes information about a grain pile. In some embodiments, the output information includes identification of a region of concern (e.g., a region of spoilage) in a grain pile based on the pulsed radar data. In some embodiments, the output information includes identification of a region of concern in a grain pile based on the pulsed radar data and the frequency modulated continuous wave radar data. In some embodiments, the output information includes information about a grain pile based on the induction data combined with pulsed radar data without frequency modulated continuous wave radar data.

[0054] In some embodiments, the output information includes grain volumetric mapping and / or moisture layers in the grain pile based on the pulsed radar data. In some embodiments, the output information includes finer details and moisture content in the grain pile based on a combination of pulsed radardata, the frequency modulated continuous wave radar data, and the magnetic induction data.

[0055] In some embodiments, the output information includes elevation mapping based on the pulsed radar data. In some embodiments, the output information includes elevation mapping based on the pulsed radar data and one or more of the frequency modulated continuous wave radar data, and the magnetic induction data. In some embodiments, the output information includes elevation mapping based on single point and / or multi point LIDAR data, and the unit 100 includes a LIDAR sensor operable to provide the LIDAR data.

[0056] Referring now to Figure 2, illustrated is a schematic diagram of another subsurface imaging system 200. Subsurface imaging system 200 is similar in some respects to subsurface imaging unit 100, and like features are indicated by like reference numbers incremented by 100.

[0057] Subsurface imaging system 200 includes a software defined radio 248, such as the LIMESDR-XTRX™. The software defined radio 248 includes a wideband transceiver 210, a switching network 220, and a field programmable gate array 272. The software defined radio 248 is coupled to a set of high frequency antennas 202a, a set of low frequency antennas 202b, and a set of time domain antennas 202c. The software defined radio 248 is coupled to the time domain antennas 202c via a configurable pulsed radar system 274 and a signal converter 276 (e.g., analog to digital converter 142 and / or digital to analog converter 144). The software defined radio 248 is coupled to the set of high frequency antennas 202a and the set of low frequency antennas 202b via radio frequency connectors 280. A down / up conversion unit 282 may be between the radio frequency connector 280 and a set of antennas. The down / up conversion unit 282 includes a mixer 214 and amplifiers 218.

[0058] The system 200 also includes a control unit 230, such as a RSPi ™. The control unit 230 is communicatively coupled to the FPGA 272. A communication module 250, such as an Arduino MKRWAN™, is communicatively coupled to the control unit 230. The system 200 also includesa power module 290 coupled to a powered component of the system to supply power thereto. The power module 290 may include, e.g., batteries, capacitors, or fuel cells. Referring to Figure 3, the configurable pulsed radar system 274 is shown in greater detail.

[0059] Referring now to Figure 4, illustrated is a subsurface imaging method 300. The method 300 includes, at step 302, moving a vehicle over a target body, the vehicle carrying the multimodal imaging unit 100. In some embodiments, the vehicle is a drone, a sprayer, a seeder, or a tractor. At step 304, the method 300 includes generating radio frequency signals.

[0060] At step 306, the method 300 includes collecting multimodal imaging data of the target surface by transmitting, using each of a plurality of sets of radio imaging antennas of the multimodal imaging module, the radio frequency signals towards the target material and acquiring echoes of the radio frequency signals. The plurality of sets of radio imaging antennas include at least three sets of antennas including high frequency antennas 102a, low frequency antennas 102b, and time domain antennas 102b.

[0061] In some embodiments, the method 300 further comprises an analysis step 308. In some embodiments, the target body comprises soil and rocks, and the analysis step 308 includes detecting the rocks in the soil using the pulsed radar data and / or the continuous wave ground penetrating radar data.

[0062] In some embodiments, the target body includes a layer of earth, and the analysis step 308 includes detecting electric conductivity, moisture amount, and / or compaction using the magnetic induction data and / or the pulsed radar data.

[0063] In some embodiments, the target body includes soil layers, and the analysis step 308 includes detecting the soil layers using the pulsed radar data.

[0064] In some embodiments, the target body includes buried tubers, and the analysis step 308 includes detecting the buried tubers using continuous wave ground penetrating radar data.

[0065] In some embodiments, the target body is an outdoor grain pile. In some embodiments, the target body includes a grain pile, and the analysis step 308 includes detecting an area of concern in the grain pile using the pulsed radar data.

[0066] In some embodiments, the target body includes a surface with varying elevation, and the analysis step 308 includes detecting an elevation map using the pulsed radar data.

[0067] It will be appreciated that numerous specific details are set forth in order to provide a thorough understanding of the example embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodiments described herein may be practiced without these specific details. Furthermore, this description and the drawings are not to be considered as limiting the scope of the embodiments described herein in any way, but rather as describing the implementation of the various embodiments described herein.

[0068] It should be noted that terms of degree such as "substantially", "about" and "approximately" when used herein mean a reasonable amount of deviation of the modified term such that the end result is not significantly changed. These terms of degree should be construed as including a deviation of the modified term if this deviation would not negate the meaning of the term it modifies. It should be noted that the term “coupled” used herein indicates that two elements can be directly coupled to one another or coupled to one another through one or more intermediate elements.

[0069] Various embodiments have been described herein by way of example only. Various modification and variations may be made to these example embodiments without departing from the spirit and scope of the invention, which is limited only by the appended claims.

Claims

CLAIMS:

1. A multimodal subsurface imaging unit to be removably mounted to a carrier vehicle, the multimodal subsurface imaging unit comprising: a wideband transceiver, including a wide band radio frequency signal generator operable to generate radio frequency signals within a wide band, a plurality of sets of imaging antennas including a set of high frequency antennas, a set of low frequency antennas, and a set of time domain antennas, each set of radio imaging antennas including at least one transmit antenna and at least one receive antenna, a switching network communicatively coupled to the wideband radio transceiver and to each of the plurality of antennas to selectively couple the wideband radio transceiver to a selected set or selected sets of the plurality of sets of radio imaging antennas to pass the radio frequency signals to the selected set or sets of radio imaging antennas, and a control unit communicatively coupled to the wideband radio transceiver and the switching network, the control unit including at least one processor and at least one data storage device and operable to control operations of the wideband radio transceiver and the switching network and receive echo signals from the plurality of sets of radio imaging antennas based on echoes of the radio frequency signals and provide the echo signals to a storage device, wherein the echo signals are suitable for analysis for feature extraction.

2. The unit of claim 1 , wherein the control unit further includes an analog to digital converter, a digital to analog converter, and a field programmable gate array operable to capture low frequency data.

3. The unit of claim 1 , wherein the control unit is communicatively coupled to the plurality of sets of radio imaging antennas via the wideband radio transceiver.

4. The unit of claim 1 , further comprising a communication interface communicatively coupled to the control unit for providing the echo signals externally.

5. The unit of claim 4, wherein the communication interface includes a wireless communication transmitter operable to transmit the echo signals to a remote location in real time.

6. The unit of claim 1 , wherein the wide band from which the wide band radio frequency signal generator is operable to generate the radio frequency signals includes a range from 10 kilohertz to 3 gigahertz.

7. A multimodal subsurface imaging system, comprising: a wideband radio transceiver, including a wide band radio frequency signal generator operable to generate radio frequency signals from a wide band, a plurality of sets of radio imaging antennas including a set of high frequency antennas for continuous ground penetrating radar data collection, a set of low frequency antennas for magnetic induction data collection, and a set of time domain antennas for pulsed radar data collection, a switching network communicatively coupled to the wideband radio transceiver and to each of the plurality of antennas to selectively couple the wideband radio transceiver to a selectedset or sets of the plurality of sets of radio imaging antennas to pass the radio frequency signals to the selected set or sets of radio imaging antennas, and at least one processor communicatively coupled to the wideband radio transceiver, the switching network, and the plurality of sets of radio imaging antennas to control operations thereof and receive echo signals based on echoes of the radio frequency signals.

8. The system of claim 7, further comprising, between the at least one processor and the plurality of sets of radio imaging antennas, an analog to digital converter, a digital to analog converter, and a field programmable gate array operable to capture low frequency data.

9. The system of claim 7, wherein the at least one processor is communicatively coupled to the plurality of sets of radio imaging antennas via the wideband radio transceiver.

10. The system of claim 7, further comprising a communication interface communicatively coupled to the control unit.

11. The system of claim 10, wherein the communication interface includes a wireless communication transmitter operable to transmit the echo signals in real time for remote processing.

12. The system of claim 7, further comprising a location unit integrated with the multimodal radio wave imaging unit for providing location information.

13. The system of claim 7, wherein the wide band from which the wide band radio frequency signal generator is operable to generate the radio frequency signals includes a range from 10 kilohertz to 3 gigahertz.

14. The system of claim 7, further comprising a vehicle carrying the plurality of sets of radio imaging antennas.

15. The system of claim 7, wherein the at least one processor is further operable to process the echo signals to generate output information based on one or more selected modalities and excluding the others.

16. The system of claim 15, wherein the output information includes one or more of the following: a) rock presence in soil based on the pulsed radar data and / or the continuous wave ground penetrating radar data; b) electric conductivity, moisture amount, and / or compaction based on the magnetic induction data, c) compaction based on the pulsed radar data; d) soil layers based on the pulsed radar data; e) tuber mapping based on the continuous wave radar data; f) tuber mapping based on the continuous wave radar data, the pulsed radar data, and the magnetic induction data; g) spoilage in a grain pile based on the pulsed radar data; h) spoilage in a grain pile based on the pulsed radar data and the continuous wave radar data; i) grain volumetric mapping and moisture layers in the grain pile based on the pulsed radar data, the continuous wave radar data, and the magnetic induction data; j) soil carbon amount; and k) elevation mapping based on the pulsed radar data.

17. A subsurface sensing method, comprising: moving a vehicle over a target body, the vehicle carrying a multimodal imaging module; generating radio frequency signals; and collecting multimodal imaging data of the target surface by transmitting, using each of a plurality of sets of radio imaging antennas of the multimodal imaging module, the radio frequencysignals towards the target material and acquiring echoes of the radio frequency signals, and wherein the plurality of sets of radio imaging antennas include at least three discrete sets of antennas including continuous wave magnetic induction antennas, continuous wave ground penetrating radar antennas, and pulsed radar antennas such that the multimodal imaging data includes magnetic induction data, continuous wave ground penetrating radar data, and pulsed radar data.

18. The method of claim 17, wherein the continuous wave magnetic induction antennas operate between 10 kilohertz and 40 kilohertz, the continuous wave ground penetrating radar antennas operate between 600 megahertz and 1 gigahertz, and the pulsed radar antennas operate with pulse transmissions spaced apart between 0.5 nanoseconds and 5 nanoseconds.

19. The method of claim 17, wherein the vehicle is a drone, a sprayer, a seeder, or a tractor.

20. The method of claim 17, wherein: a) the target body comprises soil and rocks, and the method further comprises detecting the rocks in the soil using the pulsed radar data and / or the continuous wave ground penetrating radar data; b) the target body includes a layer of earth, and the method further comprises detecting electric conductivity, moisture amount, and / or compaction using the magnetic induction data and / or the pulsed radar data; c) the target body includes soil layers, and the method further comprises detecting the soil layers using the pulsed radar data; d) the target body includes buried tubers, and the method further comprises detecting the buried tubers using continuous wave ground penetrating radar data;e) the target body is an outdoor grain pile; f) the target body includes a grain pile, and the method further comprises detecting an area of concern in the grain pile using the pulsed radar data; or g) the target body includes a surface with varying elevation, and the method further comprises detecting an elevation map using the pulsed radar data.

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