Voltage wavefront transit time sensor system

Abstract

A device and method associated therewith for measuring the transit time of a voltage pulse through a conductor for the purposes of detecting or quantifying changes in material properties when such conductor is placed in proximity of a dielectric material. The absolute value of, and the variability of, such transit times provides insight as to the dynamic or static state of the dielectric properties of any materials in proximity to the conductor. Using a variable, stepped, voltage the device and method can also discriminate transit time variability due to varying material properties at distance from the conductor.

Description

VOLTAGE WAVEFRONT TRANSIT TIME SENSOR SYSTEMPRIORITY

[0001] This patent application claims priority to U.S. Provisional Patent Application No. 63 / 640,742, entitled “VOLTAGE WAVEFRONT TRANSIT TIME SENSOR SYSTEM,” filed on April 30, 2024, and is incorporated by reference herein.FIELD OF THE DISCLOSURE

[0002] This disclosure relates to a voltage wavefront transit time measurement device.BACKGROUND

[0003] When an electromagnetic (EM) field interacts with a material, the nature of its interaction is determined by the material dielectric properties. The two physical properties of interest are permittivity, which concerns interaction with the electric field, and permeability, which concerns interaction with the magnetic field.A material with high permittivity polarizes more in response to an applied electric field than a material with low permittivity, thereby storing more energy in the material. Permittivity plays an important role in determining the capacitance of a capacitor.

[0005] Dielectric measurement is a well-defined and established field of techniques for quantifying dielectric constants for any material. However, these techniques are generally inconvenient in the application of material dielectric properties to sensor design and construction. One exception is that of the capacitor. A capacitor, by its very nature, is a sensor whose sensing capabilities are completely defined by the dielectric properties of the materials used in construction and deployment. Rotation, linear position, and proximity to dielectric material are all easily within its range of capabilities.

[0006] Prior art references, such as US 11,523,745, US 11,684,283, US 9,549,682, and US 9,035,778, show how capacitance measurement has been applied to the sensing of heartbeat and respiration of the body simply by forming a variable capacitor such that the varying permittivity of body respiration drives frequency changes in a resonant oscillator that may then be reduced to voltage and digital forms via frequency to analog and analog to digital conversions.

[0007] Being a multi-stage analog process, this measurement of capacitance is fraught with opportunities for signal degradation and noise. As an analog technique being used to sense a very small change in dielectric properties of the body, it leads to a number of problems. These problems include (1) RF interference (such as phones) directly interacts with capacitive circuits in such a way as to induce variations in capacitance that are not related to changes in dielectric properties in the body; (2) low signal levels make the signal susceptible to common amplitude modulation noise sources; and (3) electrical coupling between the body means any movement of the body with respect to the capacitor throws a huge capacitive change that swamps the smaller signals associated with the desired signals resulting in (a) an exceptionally high dynamic range of the voltage signal which is difficult and expensive to measure with sufficient resolution to provide discrimination for the very small changes in body permittivity across the full range of the sensor; and (b) difficulty in managing and discriminating external factors such as a second body, restless leg, etc., which couple with the source signal to pollute the combined signal. However, the same physical phenomena that lead us to capacitive sensing also provide the means for an alternative method.SUMMARY

[0008] A voltage differential applied to a conductor creates an electromagnetic (EM) field that radiates out from the conductor. This EM field derives from the voltage potential of the conductor in association with its surroundings. As such, it takes a finite time for a voltage potential, and its associated EM field, to develop and to propagate along the conductor.

[0009] This disclosure relates methods used to measure voltage so as to determine the time it takes for a voltage potential change to propagate through a conductor, and the change in shape of a voltage packet, or pulse, as it travels through a conductor in various configurations and for various applications, such as biomedical, industrial and commercial.

[0010] In one embodiment there is described a method that compares transit time values to obtain a dielectric characteristic of a material under test, wherein one of the transit time values is a reference transit time value from one point in a conductor to another point in the conductor, comprising: placing the conductor having conductive characteristics in proximity to the material under test; introducing one or more voltage pulses into one point of the conductor;measuring a transit time of at least one non-reflective pulse from the one or more voltage pulses from the one point of the conductor to another point in the conductor using a clock ; and comparing the transit time with the reference transit time to assist in determining the dielectric characteristic of the material under test. In another embodiment there is described a method that uses transit time values to assist in determining a dielectric characteristic of a material under test, comprising: arranging a plurality of voltage wavefront transit time sensors at different locations in a predetermined area and each being electrically connected to a conductor, such that there exists a plurality of conductors that are electrically isolated from each other in a predetermined arrangement in the predetermined area, wherein each of the wavefront transit time sensors includes a pulse generator, a receiver, a transmitter, and a clock; placing the material under test in proximity to the predetermined area; introducing one or more voltage pulses from some of the plurality of voltage wavefront transit time sensors onto the conductor associated therewith; measuring a transit time of at least one non-reflective pulse from the one or more voltage pulses from one point of the conductor to another point in the conductor for each of the some of the plurality of voltage wavefront transit time sensors and the conductor associated therewith; and using the transit times from the step of measuring to assist in determining the dielectric characteristic of the material under test..

[0011] In a further embodiment there is described a method that uses transit time values to assist in determining a dielectric characteristic of a material under test, comprising: arranging a plurality of voltage wavefront transit time sensors at different locations at a periphery of a conductive sheet; placing the material under test in proximity to the conductive sheet; introducing one or more voltage pulses from some of the plurality of voltage wavefront transit time sensors onto the conductive sheet; measuring a transit time of at least one non-reflective pulse from the one or more voltage pulses from one of the voltage wavefront transit time sensors to another one of the voltage wavefront transit time sensors; repeating the step of measuring for conductive paths between various ones of the voltage wavefront transit time sensors; and using the transit times from the different steps of measuring to assist in determining the dielectric characteristic of the material under test..

[0012] These and other features, and characteristics of the present technology, as well as the methods of operation and functions of the related elements of structure and the combination of parts and economies of manufacture, will become more apparent upon consideration of thefollowing description and the appended claims with reference to the accompanying drawings, all of which form a part of this specification, wherein like reference numerals designate corresponding parts in the various figures. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the invention. As used in the specification and in the claims, the singular form of “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise.BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIG. 1A shows a single wire conductor, according to an embodiment.

[0014] FIG. IB shows a voltage wavefront that travels through the conductor, according to an embodiment.

[0015] FIG 1C shows a DC voltage pulse of arbitrary width, amplitude, leading and trailing edge rise times.

[0016] FIG. 2 shows a single wire voltage wavefront transit time system, according to a second embodiment.|0017] FIG. 3 shows a multiple wire voltage wavefront transit time system, according to a third embodiment.

[0018] FIG. 4 shows a conductive sheet voltage wavefront transit time system, according to a fourth embodiment.|0019] FIG.5 shows a single wire voltage wavefront transit time system according to a fourth embodiment.

[0020] FIG.6 shows a single wire voltage wavefront transit time system according to a fifth embodiment.

[0021] FIG. 7 shows a 2D planar conductive mesh or sheet where each voltage wavefront transit time system uses either Pulse Position Modulation (PPM) or Pulse Width Modulation(PWM) to broadcast digital control messages to and between each VWTT sensor connected to the conductor.DETAILED DESCRIPTION

[0022] A voltage differential applied to a conductor creates an electromagnetic (EM) field that radiates out from the conductor. This EM field derives from the voltage potential of the conductor in association with its surroundings. As such, it takes a finite time for a change in voltage potential, and its associated EM field, to develop and to travel along the conductor. As a result of the applied voltage, an EM field will develop around the conductor enabling the propagation of electric potential change (increase or decrease in voltage) along the conductor. In a vacuum, this voltage potential will travel over an ideal conductor at the speed of light. However, when a conductor is placed in, or adjacent, a dielectric medium (for example, air, plastic, or water) the speed with which the voltage potential travels is reduced by the presence of the dielectric material interfering with the EM field development. Accordingly, various characteristics of any such dielectric material and / or an arrangement of the conductor(s) can be inferred by measuring and comparing the speed with which a voltage potential travels over any such conductor in the presence of varying material properties or varying geometric arrangements of the conductor.

[0023] In the following paragraphs, implementations of the present conductor transit time system will be described in detail by way of example with reference to the accompanying drawings, which are not necessarily drawn to scale, and the illustrated components are not necessarily drawn proportionately to one another. Throughout this description, the implementations and examples shown should be considered as exemplars, rather than as limitations on the present disclosure. As used herein, the “present disclosure” refers to any one of the embodiments of the disclosure described herein, and any equivalents. Furthermore, reference to various aspects of the disclosure throughout this document does not mean that all claimed embodiments or methods must include the referenced aspects.

[0024] FIG. 1A shows a single wire conductor 102, according to an embodiment. The single wire conductor 102 to a DC voltage source V. FIG. IB shows a voltage wavefront VWF that travels through the conductor 102, according to an embodiment. The conductor 102 isconnected at a time TO to the DC voltage source V. As a result of the applied voltage, an EM field will develop around the conductor 102 enabling the propagation of electric potential along the conductor 102. It takes a finite time for the field to develop and propagate from one end of the conductor to the other. As the EM field develops it forms an annular EM field front centered on the conductor 102. As a result, the voltage potential (shown in FIG. IB) rises along the conductor 102, forming a voltage wavefront VWF in the conductor 102. The EM field interacts with dielectric materials in such a way that slows the transit time of the VWF. The combined overall effect is that any change in voltage potential takes time to propagate through the conductor and the time it takes is directly related to the dielectric properties of the materials that surround it.

[0025] The measurement of this transit time over a constant conductor length therefore provides a measure of the dielectric properties of the material.

[0026] For a conductor in a vacuum, the VWF travels at the speed of light. When such a conductor is co-located adjacent any dielectric material, the VWF travels along the conductor at a speed less than the speed of light, at a speed reduced in a simple and direct relationship with the dielectric properties of the material that the conductor is co-located with.

[0027] An important side effect of this physical phenomena is that any discontinuity in dielectric properties will cause a reflective and attenuated voltage pulse to form traveling in the opposite direction to the source. This has been used in time domain reflectometry for sensing both distance (assuming the dielectric properties remain constant during the measurement interval) and dielectric properties (assuming the distance remains constant during the measurement interval). Examples are radar and lidar for distance and the open-ended coaxial probe for dielectric properties.

[0028] However, if both distance and dielectric properties are changing during the time of measurement and without some form of additional measurement or constraint, time domain reflectometry is incapable of accurately resolving either distance or dielectric properties. Whereas it may be possible to infer changes in dielectric properties from variations in reflective absorption, this too is affected by distance and resolving small variations in absorption poses a significant challenge in analog discrimination. In addition, there is value in small relativechanges in dielectric properties that cannot be detected in a reflection since the transit time of a reflection is only a measure of distance to the discontinuity.

[0029] With appropriate arrangement of transit time sensing apparatus, this application proposes the measurement of the non-reflective, end to end, transit time of a voltage wavefront within a conductor as a method to simultaneously sense distance and change in dielectric properties. The voltage wavefront transit time VWTT is the time necessary for the voltage potential to propagate from one point in a conductor to some other contiguous point within the conductor.

[0030] VWTT provides a means for dielectric change sensing that is tangibly less complex, potentially significantly lower cost and significantly less prone to analog interference or analog to digital conversion effects and that, with suitable arrangement, can be used to resolve both dielectric change and location change in a single method.

[0031] During a human body respiration, the typical respirational variation in lung permittivity is in the order of 1%. Assuming this change is fully reflected in a change in VWTT, this maps to a change of approximately 10 picoseconds end to end travel time per foot of lineal distance traveled.

[0032] FIG 1C expands on the description above and shows a stylized DC pulse traveling from left to right. Here the pulse starts when the voltage is turned on resulting in a leading, rising, voltage edge traveling across the conductor. The pulse ends when the DC voltage is removed and this results in a trailing, falling, voltage edge also traveling across the conductor. It is noted that there will be differences between the time of the leading edge vs the pulse trailing edge depending on the pulse width because the molecules relaxation time will change with different pulse widths and different bandwidths.

[0033] In recent years, the ability to accurately measure time has become cheaper and resolutions to sub 1 nanosecond are possible at the cost of $1 or less, and to resolutions of 1 picosecond at very reasonable cost in terms of viability for general, low cost, sensing applications. Further, the use of optical comb filters, combined with CMOS, provides the opportunity for femtosecond transit measurements at modest cost.

[0034] FIG. 2 shows a single wire voltage wave front transit time system 200, according to a second embodiment. The single wire transit time system 200 includes a VWTT sensor 201, a sense wire 202, and a material under test 203. The system 200 measures properties of the material under test 203 using a sense wire 202. The sense wire is similar to the conductor 102 of the first embodiment. The sensor 201 measures the time it takes for a voltage change to propagate from the transmitter 211 to the receiver 212 through the sense wire 202. When in proximity to the sense wire 202, the material 203 will alter the speed of voltage change propagation through the sense wire 202. The time that it takes for the voltage change to propagate from the transmitter 211, through the sense wire 202 in proximity to the material 203 to the receiver 212 is here called the “voltage wave front transit time” (VWTT) and the device used to measure VWTT is here known as the VWTT sensor. Variations in dielectric properties of the material under test such as, for example during respiration or a heartbeat, will cause fluctuations in the VWTT that directly map to respiration rate, respiration variability, heart rate and heart rate variability. In addition, VWTT may also be compared to base state transit times where no material, or some ‘standard’, predefined or pre-conditional material is near the sense wire 202. An example would be monitoring changes of a dielectric properties over time due to aging, illness, chemical composition or other time related dielectric changes. That the specific details of the dielectric properties of the material under test are not necessarily required in order to derive useful information about the material under test 203.

[0035] (14) The VWTT sensor 201 includes a pulse generator 210, a transmitter 211, a receiver 212, a counter 213, a digital interface 214, and a high resolution, high accuracy, sub nanosecond, oscillator 215. The oscillator and the counter together form a digital clock with one or more digital outputs. The pulse generator 210 creates a voltage pulse of widths tl and t2 with arbitrary specific pulse bandwidths and widths tl and t2 that may be of the same width or different widths and spaced at equal time or variable time intervals tO-n. In many instances, bandwidths on the order of lOOThz are preferred. These pulses are sent to the transmitter 211. The transmitter 211 is capable of meeting the pulse bandwidth requirements to shape and / or condition the VWF pulse as it should be applied to the sense wire 202.

[0036] Shaping and / or conditioning can include altering the rise and fall characteristics and times (bandwidth / frequency), the amplitude (for depth of field), the pulse width (for duration of charged field, as well as variation between rise and fall times of a pulse), and rise / falltransitions (which may manifest as frequency pollution). Molecules have particular frequencies at which they will resonate when excited by the EM field and bandwidth / frequency shaping of the pulse leading and trailing edges can be used to excite specific molecules, or groups of molecules in preference to others. This shaping can be used to thus improve signal to noise ratio of one specific molecule, or specific molecular group, by using specific leading / trailing frequencies to resonate with the target molecules or molecular groups; as increased resonance translates to increased delay and higher sensing sensitivity. This effect can be further enhanced by using the pulse amplitude to manage the depth of influence of the EM field, thus providing visibility into the distance of resonant molecules from the conductor. V ariations in pulse width and pulse interval times can be used to vary the impulse / relaxation response of different molecules or groups of molecules.

[0037] The sum of these pulse shaping efforts can be used to both improve signal to noise and in the disambiguation between molecular components of the dielectric material at various distances from the conductor.10038] The transmitter 211 then applies the voltage pulses to the sense wire 202. The transit time of both the leading and trailing edges of the voltage pulse will be hindered by the material under test 203, thereby varying the VWTT of both the leading and trailing edges of the pulse. Any time differential between the VWTT of the leading and trailing edges is due to the combination of any change in dielectric properties in the interval between the leading and trailing edge passing and any difference in bandwidth of the leading and trailing edges. The other end of the sense wire 202 is attached to the receiver 212 that detects the voltage pulse arrivals Sr(t) as a function of time t. The receiver is simply a voltage sensor that compares the received voltage against the level set voltage threshold Vth. The receiver 212 outputs a signal Pr(t) that is fed into the counter 213 along with a counter reset pulse from the pulse generator 2101. The reset signal causes the counter to clear its counters to zero and begin counting cycles delivered by the sub-nanosecond oscillator 215. Each voltage pulse received by the receiver 212 latches counters c 1 , c2, c3 , . .. , cn in turn such that the values of counters c 1 , c2, c3 , . . . , cn are available to the digital interface 214. The digital interface 214 then sends the signal to an exterior digital VO (input / output) 220 that may then be used to derive the effect of the material 203 on the sense wire 202.

[0039] The pulse generator 210 is capable of generating a single pulse or a multi-pulse train using variable or fixed inter-pulse spacing. The pulse generator 210 also anticipates the need for high bandwidth pulse generation to provide sensitivity to different resonant frequencies within dielectric materials and which will give rise to bandwidth dependent transit times. The analysis of bandwidth response allows disambiguation of various parts of the body by sensing their response to specific bandwidths of the VWF. The pulse generator 210 simultaneously generates the pulse and resets the counter 213 such that the pulse transit time can be derived from the counter.[0040| The sense wire 202 guides the voltage pulse past the material under test 203 and back to the receiver 212 which detects its arrival. Such exact, deterministic time of arrival may be further aided by the specific shaping of the pulse applied to the sense conductor 202 by the transmitter 211 as described above. The receiver 212, in turn, flags the receipt of a pulse to the counter 213 to sample and hold the time of arrival for that pulse. It is imperative that the transmitter 211 generates a repeatable wavefront with minimal jitter and that the receiver 212 senses the arrival time at the correct time with respect to the transmission time and transit time, again with minimal jitter.

[0041] Whereas these embodiments describe a collocated transmitter 211 and receiver 212, with suitable arrangement and synchronization of clocks, the transmitter and receiver may be located at disparate locations.

[0042] Dielectric interaction is only active during a change in voltage and further, the depth of EM field penetration, and thus the effect of dielectric properties on VWTT at a distance from the conductor will vary with the absolute magnitude of the voltage applied to the sense conductor 202 by the transmitter. Thus, the transmitter 211 anticipates the need to deliver variable and stepped voltage pulses and the receiver 212 anticipates the need to disambiguate the times of arrivals for each such stepped voltage level.

[0043] The counter 213 is a multistage counter capable of counting and holding multiple arrival times (c; - cn) from a single reset pulse. The clock times are read as digital counts via the digital interface 214.

[0044] Though the basic architecture of time of flight measurements is well known, the required sensitivity, deterministic repeatability and resolution requires careful and specific implementation in order to provide the required sensitivity and results. For example, the flexibility of the design of the pulse generator 210, the design capabilities of the transmitter 211 and receiver 212 pair, the accuracy and precision of the oscillator 215 and methods of variability mitigation (such as averaging and filtering), the shaping of the pulse on the conductor and the consistent and deterministic reduction to a point in time to picosecond and femtosecond resolutions are all significant details in determining the capabilities of the VWTT sensor 201.

[0045] It is noted that for certain applications, life signs in particular, the features of interest may produce very small changes in time where such changes in time are proportional to the length of wire in contact with the dielectric and depend on the collective molecular motility in the presence of the EM field and the distance of the change from the conductor. One example is the change in dielectric response of a heart during its beat that may induce changes in end to end time of flight of order femtoseconds. Another is the use of the VWTT in detecting location of a train on a rail may be induce changes in time of flight of order seconds.

[0046] Any discussion of time in relation to time of flight, must consider the notion of a clock and how to measure time. Here a clock isa digital counter (such as shown at 213, 513 & 613 in Figs. 2, 5 and 6, respectively) driven by an oscillator (such as shown by 215, 515, 615 in Figs. 2, 5 and 6, respectively) such that the counter may be triggered by successive pulse arrivals to issue one count for each successive pulse while continuing to count (cO, cl, c2, .. cn, a multishot counter) or such counter records a single value per pulse (single-shot). In both cases, such clock may further be enhanced in timing resolution by the ability to average and / or filter successive pulse counter values as one single ‘clock’ count. In such an arrangement, successive pulses may be measured singly and averaged / filtered (220) to improve timing resolution, or multiple counters can be used, in parallel, to time a single pulse (520). In this manner, any combination of multiple pulse averaging and filtering and multiple parallel counters can effect a clock of any particular resolution, and other implementations of a clock that function as described herein are properly within the scope intended herein.

[0047] In order to achieve high timing resolution, such as for VWTT to work for life sign detection, the VWTT needs to be capable of resolving time down to order femtoseconds, whichis achieved by oscillators that resonate at lower frequencies , and by the use of averaging and other filtering as described, to achieve the timing resolutions required for any given application, including femtosecond resolutions for detailed life sign detection. These techniques provide the ability of the VWTT to scale it’s timing resolution dynamically from order seconds to femtoseconds to match the needs of a diverse range of applications.

[0048]

[0049] It is thus possible to mix and match #counters and averaged counter output for any number of samples per second to be sufficient for finding, for example, the location of a train on a rail, one of the other specific implementations noted herein, to give a sense of the different applications that require various time sensitivities, in order for the teaching herein to practically be applied to such different application.

[0050] FIG. 3 shows a multiple wire voltage wavefront transit time system 300, according to a third embodiment. The multiple wire transit time system 300 uses multiple wires 302A-302D and multiple VWTT sensors 301 A-301D to measure a material under test 303. The wire 302A- 302D is measured by the VWTT sensor 301 A-301D, respectively. Each wire 302A-302D and each VWTT sensor 301A-301D is similar to the sense conductor 202 and the VWTT sensor 201 of the second embodiment, with each wire in this embodiment being electrically insulated from the other wires. By having an array of sense conductors, a two-dimensional measurement of the material 303 can be made and use to further disambiguate location and dielectric variability. Each sense conductor 302A-302D measures a different region such that taken together, a two-dimensional image of the material 303 can be created. In contrast, the singular sense conductor 202 only allows a measurement in one dimension. FIG. 3 shows the application of the VWTT sensor to a mesh of wire conductors 302A-302D with four VWTT sensors 301A- D, though other numbers of wire conductors and VWTT sensors can be implemented, with the minimum of two wires and sensors in this embodiment. Such a mesh allows sensing of location and permittivity by correlating the transit times between coordinated pulses from multiple orthogonal sensors 301A-301D.d

[0051] FIG. 4 shows a conductive sheet voltage wavefront transit time system 400, according to a fourth embodiment. The conductive sheet transit time system 400 has a conductive sheet402 made up of a plurality transmitter 21 1 receiver 212 connection points originating from and returning to VWTT sensors 401 A-401H. The conductive sheet is shown as a rectangle in shape at its perimeter, though many other shapes, including circle, oval, triangle, octagon and arbitrary, can all work. An arbitrary shape can be useful in channeling the wavefront to specific locations; examples are the shape of a human body or a ‘zigzag’ wire. In the former example, the shaping is designed to hold the EM field within a specific area, to focus effects in that area. The latter example can be used similarly to increase the length of wire in a specific area to improve sensitivity.[0052| One practical aspect to consider is that the greater the travel time, (the longer the path through the conductor) influenced by any specific dielectric feature, the higher the change in transit time and the easier it is to measure, both practically and using components (such as oscillators), that are less precise.

[0053] With the increase in the number of sense conductor VWTT devices, the conductive sheet or material 402 provides even more measurements of the material under test 403. Whereas the illustrative implementation of the second embodiment used four sense conductors, the illustrative implementation of the third embodiment uses eight VWTT connections to a contiguous conductive sheet. However, the conductive sheet system 400 is not limited to eight VWTT connections. There may be any number of VWTT connections; in one embodiment, there may be anywhere from 2 or 3 to 10 to 100 or more sense conductors. The number of VWTT devices used is dependent on the measurement specificity desired. The more VWTT devices in the system 400, the more accurate and specific the measurement can be. Each additional VWTT device applied decreases the gaps or blind spots in the conductive sheet 402. As a result, very accurate measurement of a very small surface area of the material 403 can be achieved. FIG. 4 extends the paradigm of a mesh to a potentially infinite resolution by using the continuous sheet conductor 402 and sensing the arrival times of coordinated pulses from each VWTT sensor in turn to the set of remaining VWTT sensors, to generate multiple transit times for any given pulse with each transit time depending on the dielectric properties encountered. By rapidly cycling through each VWTT sensor, sending a pulse and measuring the multiple transit times, a two-dimensional picture of the dielectric variability will be generated over the area of the sheet and over time.

[0054] Because this method senses VWTT, it does not suffer the problem of sensing potentially very low amplitude reflective signals and it is not prone to significant analog interference. Also, it is a direct transform from the physical domain into the digital domain without the complexity and expense of analog conversion.

[0055] Further, the use of a pulse and end to end transit time allows any given single voltage pulse to provide two distinct transit times, one for the head of the pulse and one for the tail of the pulse. Additionally, using suitable pulse generation techniques, the head of the pulse can be of a different bandwidth to that of the tail of the pulse providing dielectric feature disambiguation within a single pulse.10056] In FIGS. 3 and 4, multiple VWTT sensors are used. However, it is also possible to multiplex pulses from one pulse generator across multiple wires or connection points. This way, only one receiver, or some reduced number of receiver, needs to be applied.

[0057] The sense conductors in FIGS. 2-4 are preferably curved such that the wires originate from and return to the same VWTT sensors. However, it is not limited to this. It is possible for the sense conductors to originate from a first sensor and end at a second sensor. In that case, the sense conductors are positioned along a straight line. Further, the conductor can be any one of a copper or aluminum wire, plate, and sheet. Any suitable conductive material can be used for the conductor as well.

[0058] The material under test 203, 303, 403 may be a living organism, such as an animal or a human that is under examination. However, the material under test 203, 303, 403 is not limited to this as it could be any other dielectric material such as grain, flour, rock, plastic, waste materials, slurry, and / or slurry, fluids.

[0059] The conductor transit time systems 200, 300, 400 can be used in many applications. For example, the VWTT system can be used in the biomedical field when a living organism is placed on or near the conductor and transit time system is used. Vital signs such as heart rate and respiration can be detected without direct contact to the body. This conductor transit time system 200, 300, 400 proposes an alternative approach to inferring dielectric properties using VWTT measurement to achieve the same result with less complexity and greater fidelity. FIG5 shows an embodiment using multiple counters (513) being driven in parallel by a single oscillator (515), using each received pulse to create multiple counter values which are then averaged or otherwise filtered to provide a single value of increased timing resolution. It should be clear that this embodiment can further average or filter multiple such pulse values to obtain additional clock resolution.

[0060] FIG 6. shows an embodiment using multiple counters (613) being driven in parallel by a single oscillator (615) but now used in series such that a single pulse is used to provide a timing value for a plurality of sense wire segments, using one receiver (612) per single pulse, where each segment is making independent measurement of one or many materials under test (603) and each output of which may, in turn, be the average of multiple pulses.

[0061] FIG 7. shows the ability of multiple devices to share a common conductor using PWM and / or PPM in order to provide command and control networking between connected sense elements in the form of a distributed mesh network of nodes. Such networking is used to communicate details of the pulse shaping used and any particular setup parameters required, coordinate VWTT pulse start stop times such that the pattern of pulses from each node in the mesh can be temporally orchestrated to focus on specific areas of the mesh to provide dielectric feature enhancement within the bounds of the 2d planar area covered by the mesh and to ensure that only one pulse is present on the mesh at once.

[0062] All embodiments using multiple VWTT, create the problem of synchronization between each VWTT. For this synchronization, it is preferable to ensure that only one VWTT is active at any given time, with coordination between transmit and receive being essential. Such coordination is facilitated by the use of PPM and or PWM pulses where by each VWTT forms a node on a digital network. Using pulses as a form of communication and as a form of measure allows simultaneous measurements and communication. Nodes in such a mesh will also be digitally connected through ethemet, wifi and similar for the strategic control of the VWTT nodes. In the case of multiple conductors (one per sense) such as described with respect to FIG 3, the EM fields need to be disambiguated. However, in this specific case, it is also possible to coordinate multiple VWTTs with a specific pattern of pulses, which may or may not overlap, whereby the induce EM field excites the material in very specific ways. For the case of a planarsingle conductor, only one pulse is sent at a time, and specifically any subsequent pulse can’t be sent until all receivers have received the pulse currently ‘in flight’.

[0063] Using VWTT eliminates much of the RF interference problems associated with measuring capacitance including extraneous RF noise and simplifies the problem of removing extraneous environmental noise (e.g. other bodies in the room). It also opens the possibility for a significant improvement of measurement fidelity utilizing an arrangement of multiple sensors to measure VWTT in multiple dimensions such that a two-dimensional, or possibly three-dimensional, picture of the heart, respiration, and blood effects may be produced in real time for each heartbeat or each breath taken by the lungs.10064] Further, it has been shown that sufficient measurements of heart rate can be used to estimate blood pressure (BP), which would enable this technique to include additional BP fidelity by allowing the tracking of the blood pressure wave through the upper torso. When taking a measurement of the material 203, 303, 403, the heartbeat, respiration, and blood pressure are measured together and then separated by identifying the distinct portions of the heartbeat, the respiration, and the BP.

[0065] Another application for the VWTT system is in the industrial / commercial field. The length of a single wire conductor can be measured using a simple, low cost VWTT sensor to a resolution of several inches. Higher resolutions are possible at greater expense. This disclosure proposes the use of such sensing for the measurements of liquid / slurry / dry powder depths, liq- uid / slurry / dry powder flow rates, and material discrimination and / or disambiguation (e.g. on conveyor belt or in pipework).

[0066] Further, the technique particularly lends itself to railroad locomotive management. It is possible to measure the speed, distance, and direction of travel of any locomotive on any part of a road reached by a single sensor connecting to the rails and using the rails and train axles as the sense wire. This eliminates the need for more complex means of vehicle signaling, and in particular, eliminates the need to partition the track into electrically separate sections. By being able to measure the locomotive for significantly lower costs, this technique may be a significant commercial advantage. In addition, the technique would be of particular interest to some communities, being simpler to install and use and having greater utility than existingavailable systems. A specific implementation of a device that uses transit time values to assist in determining a dielectric characteristic of a material under test, comprises: a plurality of voltage wavefront transit time sensors positioned at different locations in a predetermined area and each being electrically connected to a conductor, such that there exists a plurality of conductors that are electrically isolated from each other in a predetermined arrangement in the predetermined area, wherein each of the wavefront transit time sensors includes a pulse generator, a receiver, a transmitter, and a clock, wherein one or more voltage pulses from some of the plurality of voltage wavefront transit time sensors are introduced onto the conductor associated therewith, and a transit time of at least one non-reflective pulse from the one or more voltage pulses from one point of the conductor to another point in the conductor is measured using one of the voltage wavefront transit time sensors; and a processor that uses the measured transit times to assist in determining the dielectric characteristic of the material under test.

[0067] Another specific implementation of a device that uses transit time values to assist in determining a dielectric characteristic of a material under test, comprises: a plurality of voltage wavefront transit time sensors arranged at different locations at a periphery of a conductive sheet, a pulse generator in one of the voltage wavefront transit time sensors introduces one or more voltage pulses onto the conductive sheet; and a different one of the voltage wavefront transit time sensors measures a transit time of at least one non-reflective pulse from the one or more voltage pulses from one of the voltage wavefront transit time sensors to another one of the voltage wavefront transit time sensors. This hardware can be used to repeat the measuring for conductive paths between various ones of the voltage wavefront transit time sensors, and processor can then use the transit times from the different measurements to assist in determining the dielectric characteristic of the material under test.

[0068] Another specific implementation compares transit time values to obtain a dielectric characteristic of a material under test, wherein one of the transit time values is a reference transit time value from one point in a conductor to another point in the conductor, comprising a voltage wavefront transit time sensor that introduces one or more voltage pulses into one point of the conductor and the measures a transit time of at least one non-reflective pulse from the one or more voltage pulses from the one point of the conductor to another point in the conductor using a clock, with the transit time being compared with the reference transit time using a processor to assist in determining the dielectric characteristic of the material under test.

[0069] Although the present technology has been described in detail for the purpose of illustration based on what is currently considered to be the most practical and preferred implementations, it is to be understood that such detail is solely for that purpose and that the technology is not limited to the disclosed implementations, but, on the contrary, is intended to cover modifications and equivalent arrangements that are within the spirit and scope of the appended claims. For example, it is to be understood that the present technology contemplates that, to the extent possible, one or more features of any implementation can be combined with one or more features of any other implementation.

Claims

What is claimed is:

1. A method that uses transit time values to assist in determining a dielectric characteristic of a material under test, comprising: arranging a plurality of voltage wavefront transit time sensors at different locations in a predetermined area and each being electrically connected to a conductor, such that there exists a plurality of conductors that are electrically isolated from each other in a predetermined arrangement in the predetermined area, wherein each of the wavefront transit time sensors includes a pulse generator, a receiver, a transmitter, and a clock; placing the material under test in proximity to the predetermined area; introducing one or more voltage pulses from some of the plurality of voltage wavefront transit time sensors onto the conductor associated therewith; measuring a transit time of at least one non-reflective pulse from the one or more voltage pulses from one point of the conductor to another point in the conductor for each of the some of the plurality of voltage wavefront transit time sensors and the conductor associated therewith; and using the transit times from the step of measuring to assist in determining the dielectric characteristic of the material under test.2.The method of claim 1 , wherein the plurality of voltage wavefront transit time sensors is at least four, with at least two of the plurality of voltage wavefront transit time sensors connected to at least two conductors that are substantially in one parallel orientation, and at least another two of the plurality of voltage wavefront transit time sensors connected to at least another two conductors that are substantially in one parallel orientation and at a different orientation than the at least two conductors.

3. The method of claim 1 wherein a predetermined period between a first predetermined pulse on one of the plurality of conductors and a second predetermined pulse one another one of the plurality of conductors is determined to allow the first predetermined pulse to interact with the material under test prior to the second predetermined pulse arriving at the material under test, and wherein the clock has a resolution that is 100 picoseconds or better.

4. A method that uses transit time values to assist in determining a dielectric characteristic of a material under test, comprising arranging a plurality of voltage wavefront transit time sensors at different locations at a periphery of a conductive sheet; placing the material under test in proximity to the conductive sheet; introducing one or more voltage pulses from some of the plurality of voltage wavefront transit time sensors onto the conductive sheet; measuring a transit time of at least one non-reflective pulse from the one or more voltage pulses from one of the voltage wavefront transit time sensors to another one of the voltage wavefront transit time sensors; repeating the step of measuring for conductive paths between various ones of the voltage wavefront transit time sensors; and using the transit times from the different steps of measuring to assist in determining the dielectric characteristic of the material under test.

5. The method of claim 4, wherein the plurality of voltage wavefront transit time sensors is at least three, and each of the at least three voltage wavefront transit time sensors arranged around a periphery of the conductive sheet.

6. The method of claim 5, wherein the conductive sheet has a shape that is one of a rectangle, triangle, circle, oval or arbitrary, and is constructed of one of a conductive plate and a conductive mesh.

7. The method of claim 4, wherein the one or more voltage pulses from some of the plurality of voltage wavefront transit time sensors are each a voltage pulse train, and wherein the step of introducing includes encoding the voltage pulse train both in time and space to provide discrimination of pulse arrival times in the presence of overlapping pulses or overlapping pulse trains.

8. The method of claim 4 wherein at least one of the wavefront transit time sensors includes a pulse generator, a receiver, a transmitter, and a clock, and wherein the clock has a resolution associated with the dielectric characteristic of the material under test.

9. A method that compares transit time values to obtain a dielectric characteristic of a material under test, wherein one of the transit time values is a reference transit time value from one point in a conductor to another point in the conductor, comprising: placing the conductor having conductive characteristics in proximity to the material under test; introducing one or more voltage pulses into one point of the conductor; measuring a transit time of at least one non-reflective pulse from the one or more voltage pulses from the one point of the conductor to another point in the conductor using an clock; and comparing the transit time with the reference transit time to assist in determining the dielectric characteristic of the material under test.

10. The method of claim 9, wherein the step of introducing includes driving the one or more voltage pulses with varying bandwidths in order to resonate with varying dielectric properties of the material under test.

11. The method of claim 9, further comprising: mitigating a variability of the clock to accurately determine the transit time of the at least one non-reflective pulse from the one or more voltage pulses across the conductor.

12. The method of claim 9, wherein the step of introducing includes shaping the one or more voltage pulses by adjusting at least one of a rise time of the one or more pulses, an amplitude of the one or more pulses, a width of the one or more pulses, and a rise / fall transition of the one or more pulses.

13. The method of claim 9, wherein the material under test is one of a live body, a biological material, a bulk property of a flowing, containerized, or stacked material, and a conductive material.

14. The method according to claim 9, wherein the dielectric characteristic of the material under test is used to determine another characteristic associated with the material under test.

15. The method according to claim 14 wherein the another characteristic is one of a heartbeat, respiration, contamination, and continuity of a conductive material.

16. The method of claim 9, wherein the one or more voltage pulses is a pulse train, and the step of introducing includes varying voltage levels of the pulse train to vary the range of the EM field and disambiguate dielectric features at varying distances from the conductor.

17. The method of claim 9, wherein the step of introducing includes providing differing pulse bandwidths using a pulse generator to improve resonant dielectric sensitivity with various materials within the material under test.

18. The method of claim 9, wherein the one or more voltage pulses is a voltage pulse, and wherein the step of introducing includes generating, via a pulse generator, the voltage pulse with differing bandwidths for a head and a tail of the one or more voltage pulses.

19. The method of claim 18, further comprising: using differing bandwidths of the head and tail of the voltage pulse to elicit resonant response with two different dielectric materials within the material under test with the voltage pulse.

20. The method of claim 9, wherein there is multiple clocks and multiple conductors, and the step of measuring coordinates multiple measurements in time at a distance.

21. The method of claim 9 wherein the reference time transit value is obtained under vacuum conditions.

22. The method of claim 9 wherein the clock has a resolution that is at least one femtosecond.

23. The method of claim 9 wherein there is included multiple conductors, and the steps of introducing and measuring are performed in a multiplexed manner across the multiple conductors.

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