摘要:
A non-invasive method of buried-utility-mapping includes using a long wavelength gradiometric ground penetrating radar to “see” patches of conductive material below ground and buried pipes and electrical conductors that are all constantly radio-illuminated by local AM radio broadcasts. The underground infrastructure of entire cities can be surveyed this way, point-by-point over time. A short wavelength part of the gradiometric ground penetrating radar operates shoulder-to-shoulder with the magnetic part and is able to improve shallow object resolution, map moisture build-ups under roads, and spot contaminated soils. Two gradiometric ground penetrating radar technologies, cameras, and navigation receivers can be mounted on city vehicles and a daily collection of their data batch transformed by digital processing algorithms into detailed and automatically updating false-color maps of the underground utilities of the whole city and other buried infrastructures.
摘要:
A municipal infrastructure maintenance system uses a ground vehicle to move an antenna array in back-and-forth sweeps over large areas or distances. The antenna array comprises dozens of compartmentalized radio dipole antennas arranged laterally, shoulder-to-shoulder across the width of each sweep. An antenna switch matrix is connected between the antenna array and a ground-penetrating-radar (GPR) set and provides electronic aperture switching and selection, and the ability to laterally register one sweep to the next. The antenna array is extended out in front of the ground vehicle on a pivotable boom, and the cantilevered weight is a primary concern. The antenna array is constructed with aluminum-on-aluminum honeycomb panels slotted and folded around dozens of resistive-card compartment separators. Printed circuit boards with matching baluns are also slotted to receive tabs on the resistive cards, and their dipole elements are resistive loaded to quench crosstalk and near field effects.
摘要:
An automatic frequency control is used to keep a continuous wave (CW) transmission tuned to the resonant frequency of a resonant microwave patch antenna (RMPA). Changes in loading and the bulk dielectric constant of the mixed media in front of the RMPA will affect its resonant frequency and input impedance. A significant shift in the measured input impedance is interpreted as an object moving nearby, and the phase angle of the measured input impedance is used to estimate the direction of an object's movement.
摘要:
An underground tunnel detection system does not employ radar. Instead, an automatic frequency control is used to keep a continuous wave (CW) transmission tuned to the resonant frequency of a resonant microwave patch antenna (RMPA). Changes in loading and the bulk dielectric constant of the mixed media in front of the RMPA will affect its resonant frequency and input impedance. A significant shift in the measured input impedance is interpreted as a possible tunnel, and the phase angle of the measured input impedance tends to indicate a slightly forward or aft position relative to the detection system rolling over it on the ground surface.
摘要:
A movement detection system includes a microwave antenna able to transmit microwave frequency signals into a space. An electronics controller is connected to the microwave antenna, and is configured to continually measure the impedance of the microwave antenna while it transmits microwave frequency signals into the space. An interpretive device is connected to receive impedance measurements from the electronics controller, and is configured to interpret and report changes in the magnitude and phase angles of individual impedance measurements as the passing of things and their direction through the space.
摘要:
A method utilized with an underground conductor detection system for calibrating a downhole transmitter to compensate for detuning of the transmitter antenna by geologic formations. The method comprises sending a synchronization signal to the transmtter antenna, measuring the current flow through the transmitter antenna and adjusting the current to a constant level, and measuring the phase difference between the transmitter antenna current and the synchronization signal. A receiver transmitter is calibrated by sending a synchronization signal to a radiating antenna in the receiver that in turn sends a calibration signal to the receiver antenna that is directed over the entire signal pathway back to surface located signal processing equipment. Another method of underground conductor detection sends a surface wave to the downhole receier to cancel the effect of the surface wave modulation on a target wave being radiated by the underground detector. Another method of underground conductor detection utilizes a receiver tuned loop antenna oriented orthogonal to the magnetic dipole of the transmitter antenna for discriminating against reception of a primary wave. Another method of detecting anomalous geological zones such as tunnels, utilizes a low to medium frequency tomographic scan to cancel the effect of geological conductivity noise in a high to very high frequency tomographic scan of a region suspected of containing ther anomalous geological zone.
摘要:
Instrumentation and procedures for detecting geological anomalies occurring in layered coal formations. The instrumentation comprises a medium frequency continuous wave narrowband FM transmitter and receiver pair. Two instrument configurations are disclosed with one being a portable instrument for use within an existing mined area and another being a downhole instrument for insertion into boreholes in unmined areas. Survey procedures are provided to detect anomolies through signal attenuation, path attenuation and signal phase shift. Continuity measurements provide data to determine the existance of anomalies. Tomographic techniques are employed to provide a visual image of the anomaly. Computer aided reconstruction techniques provide such visual images from the generated data.
摘要:
An electromagnetic gradiometer (EMG) survey kit includes a lightweight man-carry boom about ten feet long. Matched magnetic dipole antennas are attached at each end and connected to a differential EMG receiver able to make measurements in the picoTelsa range. A pair of staging tripods allow the man-carry boom to be prepared for field use and assist the user in positioning themselves under a shoulder sling. An air core transmitter loop antenna and a low frequency square wave generator are spotted nearby a survey on the ground surface. Its emissions will illuminate any underground conductive structures with primary electric field waves. These in turn will reradiate near field magnetic waves that can be detected by the EMG receiver while walking around in a search area on the ground surface. GPS navigation receivers are used to locate and log the changing positions of the EMG receiver and stationary loop transmitter.
摘要:
A multi-modal ground penetrating radar includes a radar set configured to launch predistorted double-sideband (DSB) suppressed-carrier modulated continuous waves (CW) to illuminate and penetrate a ground surface. A variable frequency modulator is connected to modulate a continuous wave (CW) carrier frequency generator within the radar set to yield a double-sideband suppressed carrier output. A lateral single-file array of antennas is configured to be flown closely over the surface of the ground. A multiplexing switch is connected to the array of antennas and configured to selectively switch individual ones of the antennas to the radar set. Any early arriving signals returned from geologic clutter and surface reflections are suppressed in synchronous detection in relation to signals received by the array of antennas from less shallow depths. Interesting objects below the ground surface are detected and located by the late arriving signal reflections.