초록 ▼

An aerial electronic system for detection of surface and underground threats comprises an electromagnetic (EM) gradiometer flown aloft over the possible ground and underground threats to a convoy. The EM gradiometer is disposed in a Styrofoam torpedo shaped pod that is towed in flight behind an airp

An aerial electronic system for detection of surface and underground threats comprises an electromagnetic (EM) gradiometer flown aloft over the possible ground and underground threats to a convoy. The EM gradiometer is disposed in a Styrofoam torpedo shaped pod that is towed in flight behind an airplane. An illumination transmitter and loop antenna mounted to the airplane radiate a primary EM wave that travels down to the ground surface and penetrates beneath. Frequencies of 80 KHz to 1 MHz are selected according to whether the targets are laying on the surface or deeply buried. Detonation wire pairs, buried cables and pipes, and other conductors will re-radiate a secondary wave that can be sensed by the EM gradiometer. A reference sample of the transmitter signal is carried down a fiberoptic from the airplane to the towed pod. This signal is used in the synchronous detection to measure the secondary EM wave phase.

대표청구항 ▼

The invention claimed is: 1. An airborne system for electronic detection of surface and underground threats, comprising: a primary electromagnetic (EM) wave radiator for radio illuminating a local area; an EM gradiometer for detecting secondary EM waves from objects illuminated by a primary EM wave

The invention claimed is: 1. An airborne system for electronic detection of surface and underground threats, comprising: a primary electromagnetic (EM) wave radiator for radio illuminating a local area; an EM gradiometer for detecting secondary EM waves from objects illuminated by a primary EM wave; means for providing a synchronizing reference signal from the primary EM wave radiator to the EM gradiometer for synchronous detection with right and left magnetic dipole antennas; an airborne vehicle for lifting the EM gradiometer aloft over said local area during periods said objects are radio illuminated; and a graphical user interface (GUI) for processing phase and amplitude measurements of said secondary EM waves, and for displaying information about the location of threat objects illuminated by said primary EM wave in said local area passing underneath the airborne vehicle. 2. The system of claim 1, wherein: the primary EM wave radiator is not carried by the same airborne vehicle to prevent saturating the EM gradiometer with said primary EM waves. 3. The system of claim 1, further comprising: a tow pod in which the EM gradiometer is mounted and for being towed in flight behind an airplane; a tether for connecting the tow pod to said airplane, and including a fiberoptic cable as a means for providing a synchronizing reference signal; and a loop antenna for mounting to said airplane and providing for the primary EM wave radiator. 4. The system of claim 1, further comprising: a radio buoy providing for the primary EM wave radiator, and which can be dropped to the surface of said local area. 5. The system of claim 4, further comprising: a transmission control means for generating said primary EM wave only during requested or scheduled time slots. 6. The system of claim 1, further comprising: at least one of a blimp or helicopter providing for the airborne vehicle and that can hover and linger over said local area. 7. A dual-axis EM gradiometer, comprising: a first pair of left and right magnetic dipole antennas coaxial to one another and wound on opposite ends of a common cylindrical core; a second pair of left and right magnetic dipole antennas coaxial to one another and wound on opposite ends of a common cylindrical core, and set orthogonal to and in a horizontal parallel plane with the first pair of left and right magnetic dipole antennas; a synchronous receiver for recovering phase and amplitude information for secondary EM wave signals recovered by the first and second pairs of left and right magnetic dipole antennas, and using synchronous detection to produce corresponding phase and amplitude measurements; and a navigation receiver for producing position tags that can identify the locations of objects radiating said secondary EM wave signals. 8. An airborne system for electronic detection of surface and underground threats, comprising: a primary electromagnetic (EM) wave radiator for radio illuminating a local area; a first pair of left and right magnetic dipole antennas coaxial to one another and wound on opposite ends of a common cylindrical core; a second pair of left and right magnetic dipole antennas coaxial to one another and wound on opposite ends of a common cylindrical core, and set orthogonal to and in a horizontal parallel plane with the first pair of left and right magnetic dipole antennas; a synchronous receiver for recovering phase and amplitude information for secondary EM wave signals recovered by the first and second pairs of left and right magnetic dipole antennas, and using synchronous detection to produce corresponding phase and amplitude measurements; and a navigation receiver for producing position tags that can identify the locations of objects radiating said secondary EM wave signals; means for providing a synchronizing reference signal from the primary EM wave radiator to the synchronous receiver; an airborne vehicle for lifting the first and second pairs of left and right magnetic dipole antennas aloft over said local area during periods said objects are radio illuminated; and a graphical user interface (GUI) for processing phase and amplitude measurements of said secondary EM waves, and for displaying information about the location of threat objects illuminated by said primary EM wave in said local area passing underneath the airborne vehicle.