# US 2008/0185903 A1 · Look-ahead radar and horizon sensing for coal cutting drums and horizontal directional drills > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2008/0185903 A1 - Document ID: US20080185903A1 - Status: Published application - Kind: A1 - Application number: 12/053,611 - Filed: 2008-03-23 - Published: 2008-08-07 - Earliest claimed: 2006-06-29 - Assignees: Stolar, Inc. - Inventors: Igor Bausov; Gerald L. Stolarczyk; Larry G. Stolarczyk; Richard B. Main - Web page: https://patentgrep.com/patent/US20080185903A1 ## CPC - E21C 27/24: by milling means acting on the full working face {, i.e. the rotary axis of the tool carrier being substantially parallel to the working face (similar machines for tunneling E21D9/1026)} - E21C 35/08: Guiding the machine - E21C 35/302: {Measuring, signaling or indicating specially adapted for machines for slitting or completely freeing the mineral (measuring or indicating on tunneling machines E21D9/003)} - G01S 13/32: using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated - G01S 7/4052: {by simulation of echoes} - G01S 7/4056: {specially adapted to FMCW} - G01S 7/4082: {using externally generated reference signals, e.g. via remote reflector or transponder} - G01S 13/885: {for ground probing (prospecting or detecting using electromagnetic waves G01V3/12)} - E21C: MINING OR QUARRYING - G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES ## Abstract A coal-mining machine uses a ground-penetrating radar based on a software-definable transmitter for launching pairs of widely separated and coherent continuous waves. Each pair is separated by a constant or variable different amount double-sideband suppressed carrier modulation such as 10 MHz, 20 MHz, and 30 MHz. Processing suppresses the larger first interface reflection and emphasizes the smaller second, third, etc. reflections. Processing determines the electrical parameter of the natural medium adjacent to the antenna. Deep reflections at 90-degrees and 270-degrees create maximum reflection and will be illuminated with modulation signal peaks. Quadrature detection, mixing, and down-conversion result in 0-degree and 180-degree reflections effectively dropping out in demodulation. ## Claims ### Claim 1 An earth-penetrating radar for guiding mining machinery, comprising: a mounting to a mining machine for protecting and enclosing an earth-penetrating radar; a radar transmitter for launching pairs of separated and coherent continuous waves in a double-sideband suppressed-carrier modulation through the air; a radar receiving antenna for placement proximate to an air interface with a first layer of material, and having impedance characteristics that depend on a surrounding natural medium adjacent to the antenna and an operating frequency; a radar receiver with coherent demodulation for suppressing a first reflection of radio signals emitted by the radar transmitter from an air interface with a first layer of material and received by the radar receiving antenna; a receiver processor for determining any electrical parameters of the natural medium adjacent to the antenna from stored a priori data and impedance measurements of the radar receiving antenna; a radar processor for calculating the depth of an interface between said first layer of material and a second deeper layer of material, by measuring a signal delay of a second reflection of radio signals emitted by the radar transmitter from said first and second material interface which was received by the radar receiving antenna; wherein, said earth-penetrating radar provides for guidance of said mining machine during operation. ### Claim 2 (depends on 1) The radar of claim 1, wherein: the whole is mounted to a coal-cutting drum on a mining machine; said first layer of material comprises coal; and said second layer of material comprises at least one of water, boundary rock, and voids. ### Claim 3 (depends on 1) The radar of claim 1, further comprising: a software-defined radio transceiver with program software to implement the radar transmitter and radar receiver, wherein a software programming enables a switch in operational modes between near-field and far-field signal detection. ### Claim 4 (depends on 3) The radar of claim 3, further comprising: a modulation process for generating a frequency difference between pairs of frequencies in launched waves; wherein, if a variable frequency is used by the software-defined transceiver, then pairs of tunable resonant microstrip patch antennas are included; wherein, if a constant frequency difference is used by the software-defined transceiver, then a wide-bandwidth antenna is included with a swept or stepped-frequency continuous-wave (SFCW) function. ### Claim 5 (depends on 1) The radar of claim 1, wherein: the radar receiver accepts a received modulation signal with a phase range that starts at 0-degrees at a radar transmitter antenna, and suppresses said first reflection after coherent demodulation, then the modulation signal phase is changed by 90-degrees by the radar transmitter and said first reflection is measured again to determine in situ electrical parameters of any intervening natural medium. ### Claim 6 (depends on 1) The radar of claim 1, wherein: the radar transmitter and receiver use deep reflections at 90-degrees and 270-degrees phase to create maximums in reflections that will be illuminated with modulation signal peaks, and the radar receiver uses quadrature detection, mixing, and down-conversion result in 0-degree and 180-degree reflections effectively to drop out such demodulation. ### Claim 7 (depends on 1) The radar of claim 1, further comprising: a software-definable transceiver programmed as a geologic media penetrating radar with a direct digital synthesizer (DDS) for synthesizing pairs of many coherent first and second continuous waves (CW) with frequencies of ωo−ωi, and ωo+ω2 etc., as individual pairs separated in frequency by a constant or variable frequency difference; wherein, said pairs of continuous waves create a double-sideband, suppressed-carrier waveform, and the suppressed carrier may be held constant, swept, or stepped in frequency (ωo) across the operating frequency range of the radar. ### Claim 8 (depends on 7) The radar of claim 7, wherein: said suppressed carrier and modulation signal magnitudes and phases are software controlled, the suppressed carrier phase is θc and the modulation phase is θm, and a difference in frequency between the sidebands ωo−ω1, ωo+ω2 is the modulation frequency ω m = ω 2 + ω 1 2 . ### Claim 9 (depends on 7) The radar of claim 7, further comprising: a circuit to prevent spurious signals from conflict with the mixed-down intermediate frequency (intermediate frequency) amplifier passband signal, wherein, ωo−ω1, ωo+ω2, ω2 and ω1, and heterodyne frequencies ω3 and ω4 are each outside the passband of any intermediate amplifier (ωIF≠ωm, ω1, ω2, ω3, and ω4). ### Claim 10 (depends on 7) The radar of claim 7, further comprising: an intermediate amplitude band pass center frequency ωIF=ω4−ω2=ω1−ω3, wherein, ω2≠ω1 and ω3≠ω4, the suppressed carrier frequency, ω cm = ω 2 - ω 1 2 + ω 0 and the heterodyne frequency is ω cH = ω 4 - ω 3 2 + ω 0 , and a distance to any target continues in the phase terms ωmτ and ωcmτ. ### Claim 11 An earth-penetrating radar method, comprising: using a near measurement mode and a far measurement mode for predistortion and calibration of a transmitted waveform and a carrier suppression; setting a radar first to near measurement mode to measure near-antenna signals reflected from a first interface by setting a phase of a modulation signal to θm to 0 (π) during a calibration; processing a near measurement mode, wherein a first sideband is tuned off and a magnitude and phase are a measurement of a second sideband alone; repeating a measurement for an opposite sideband; adjusting magnitudes of said sidebands to be equal in value and adjusting the phase θm to produce 0-degrees; adjusting θc is adjusted to zero to compensate for a frequency response in the radar and antennas; then switching to a far measurement mode that sets θ m = π 2   or   3  π 2 such that any first interface reflection is suppressed using polarized antennas for any additional suppression; and using a software-defined transceiver for phase-coherent detection of the depth of said second interface reflection. ### Claim 12 (depends on 11) The earth-penetrating radar method of claim 11, further comprising: dynamically predistorting each of a pair of first and second continuous waves' magnitude and phase to account for frequency response nonlinearities with a feedback-enabled predistorter when operating in a near measurement mode. ### Claim 13 (depends on 12) The earth-penetrating radar method of claim 12, further comprising: predistorting any received waveform phase by computing an inverse tangent of an intermediate-frequency signal in phase (I) and quadrature (Q) components and then dividing by ωcm; wherein, θc measured and set to cause θc+ωcmτ to be zero so a first interface reflection will occur at τ=0. ### Claim 13 (depends on 12) The earth-penetrating radar method of claim 12, further comprising: predistorting a modulation phase by first measuring a magnitude of an intermediate frequency signal as a predistorted waveform suppressed carrier frequency is incremented in any FMCW or SFCW radar operating frequency range; and solving simultaneous equations for cos(ωmτ) and a range to a target. ### Claim 14 An earth-penetrating radar, comprising: a power amplifier and antenna for launching corrected versions of coherent pairs of said first and second continuous wave frequencies into a geologic heterogeneous media with different constituent electrical parameters for causing first, second, etc. interface reflected waves to be received; a receiver and antenna for collecting signals reflected from a first interface and other signals reflected or scattered from buried objects and interfaces of material with contrasting electrical parameters; a down-converter and coherent demodulator for coherent demodulating of an in-phase I=cos(θm+ωmτ1)cos(ωc+ωcmτ1)+cos(θm+ωcmτ2)cos(θcm+ωcτ2)+ . . . , and Q=cos(θm+ωmτ1)sin(θc+ωchτ1)+cos(θm+ωmτ2)sin(θc+ωcmτ2)+ . . . , where θm is a processor-controllable phase shift (π/2, 0, 3π/2, 2π) . . . , ωm is the modulation frequency of a double-sideband suppressed carrier or phase-modulated signal, and θc is a carrier phase with a frequency of ωcm; a processor for determining the magnitude of each reflection as M=|cos(θm+ωmτ)| for each pair of transmitting continuous waves, wherein τ1 represents the echo delay time occurring for reflections from the surface near the antenna and τ2 represents the echo delay time occurring for more distant reflections from buried objects and interfaces; a device for predistortion that results in a modulation signal phase θm being set to zero when π1=0 in a far measurement mode calibration process, and a predistorted modulation signal phase is set to a near measurement mode and then measured in a far measurement mode to determine a distance (R) to a second interface by measuring ωmτ in the intermediate frequency. ### Claim 15 (depends on 13) The radar of claim 13, further comprising: a processor for maximizing a magnitude (M), wherein, a second interface or object reflection from a location, R=λm/8, where λm=c/fm×√{square root over (∈r)} is 3×108 meters per second) and fm is the modulation frequency. ### Claim 16 (depends on 13) The radar of claim 13, further comprising: a switch for applying FMCW radar if an allowable measurement time for a SFCW radar is too short; wherein, if a boundary or target object is less than one-half a suppressed-carrier wavelength away from a pair of antennas, a DSB suppressed carrier frequency is set to a constant carrier frequency, ωcm, and if a boundary object is more than λ/2, a swept- or stepped-frequency radar is applied.