Matches 51 - 69 out of 69 < 1 2
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4628299 Seismic warning system using RF energy monitor  
The ambient broadband radio frequency field strength from broadcast stations is monitored (FIG. 4) by periodic sampling (50, 52). A warning indication is provided if the field strength drops...
4507611 Method for detecting surface and subsurface anomalies of the earth using vertical current measurements  
A method for locating and evaluating surface and subsurface anomalies. Solar wind results in a multi-frequency, high energy ionic impingement at the terrestrial poles of the earth. Monitoring the...
4198596 Device for direct and continuous receiving and measuring of electrical magnetic and acoustic signals  
A direct and continuous receiving and measuring device for electrical, magnetic and acoustic signals comprises an amplifier stage and a broadband filtering stage at the input, a local oscillator...
4088998 System for detecting nuclear explosions  
1. Apparatus for detecting underground nuclear explosions comprising antenna means located in the dielectric substance of a deep waveguide in the earth and adapted to detect low frequency...
3942101 Method for locating and evaluating geothermal sources of energy by sensing electrostatic voltage gradients  
A method and apparatus for locating and evaluating geothermal sources of energy wherein it is known that the earth has electrical currents and that these currents are reflected in electrostatic...
3911435 Dual frequency radiometer  
Disclosed is a dual frequency radiometer concept whereby selection of operating frequencies allows the detection and discrimination of metal, water, tarmac, concrete and wet soil from natural...
3866111 Method of mineral exploration by detecting electromagnetic energy at power line frequency  
A method for exploring for subsurface electrically conductive bodies in which an existing electrical power transmission line is used as a source or transmitter of electromagnetic energy departed to...
3662260 ELECTRIC FIELD MEASURING INSTRUMENT WITH PROBE FOR SENSING THREE ORTHOGONAL COMPONENTS  
An instrument is disclosed which includes a probe for sensing the x, y, and orthogonal components of an electric field occurring at any given place in an environmental medium and for producing a...
3594633 GEOPHYSICAL EXPLORATION METHOD AND APPARATUS USING THE VERTICAL ELECTRIC COMPONENT OF A VLF FIELD AS A REFERENCE  
A geophysical exploration method and apparatus utilizing VLF fields produced by distant transmitters as a source of primary field. The vertical electric alternating field component of the primary...
3398356 Method utilizing a pair of subsurface antennas for determining the physical properties effecting radio energy propagation through earth  
3392327 Detection of electroseimic signals employing salt domes  
3391334 Resistivity logging based upon electromagnetic field measurements carried out with three vertically spaced detectors  
3363457 Methods of measurement of radiant energy from subsurface formations  
3324385 Method and apparatus including movable armature means and transient electromagnetic wave detecting means for locating anomalous bodies  
3267419 Automatic instrumented diving assembly  
3197704 Passive radars for measuring thermal noise using plural local oscillations  
3136943 Geophysical prospecting method utilizing the electric field component of the earth's natural transient electromagnetic fields  
3087111 Geophysical exploration apparatus  
3028596 Radiometer technique for classifying materials  
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