Abstract: The invention includes a method and apparatus for detecting geophysical phenomena by the use of a synthetic pulse radar. A radar transmitter generates a plurality of component signals of different frequencies which approximate at least a portion of the Fourier transform of a radar short pulse. These component signals are transmitted simultaneously for modulation by the geophysical phenomena, and the modulated component signals are substantially simultaneously received in a receiver. The receiver divides the component signals, and as to each determines representative parameters. The invention also includes a heterodyne receiver which operates with a fixed IF frequency and incorporates a single frequency quadrature system.

Abstract: A method for boring a hole so that its axis is substantially parallel to the axis of a previously bored hole for positioning an acoustical transmitter and receiver against the hole of the hole being bored so that their position on the wall lies on a horizontal plane through the axis of the bore hole being bored. Then transmitting an acoustical frequency acoustical signal into the wall of the hole. The reflected signal is then received from the adjacent wall along with other unwanted additional reflections. The phase shift is then determined between the transmitted and received signal and the changes in the distance between the wall of the bore hole is then determined.

Abstract: The present invention comprises a short-pulse radar guidance tool which determines borehole-to-roof and borehole-to-floor distances along a coal seam by measuring the travel times of electromagnetic pulses transmitted from the tool and reflected back to a receiving antenna in the tool from the interface at the roof or floor of the coal seam. The tool includes a high frequency electromagnetic pulser, a directional transmitting antenna, a directional receiving antenna, a battery power source, and control circuitry for performing all control and transmitting/receiving functions at the tool location. Placement of the transmitting antenna at a point intermediate the control circuitry and the receiving antenna acts to reduce indirect electromagnetic coupling between the antennas. Circuit isolators are used to further attenuate RF crosstalk occuring between the control circuitry and the receiving antenna.

Abstract: A method for measuring the velocity of earth surface motion utilizing coherent light energy which comprises steps of generating and directing a coherent light beam toward a selected earth surface position, reflecting said beam from a stationary reflector located at the earth surface position, and simultaneously reflecting said beam from a reflector at said earth surface position which moves with earth surface motion; and, detecting the reflected beam, including both the reflection path components, to derive an instantaneous difference frequency that is proportional to the velocity of the earth surface motion.

Abstract: This invention relates to pulse radar detection of targets in extended media, including natural phenomena such as oil, coal and ore deposits within the earth. In particular, this invention relates to a pulse radar system employing a synthetic pulse formed from a Fourier spectrum of frequencies generated and detected by a digitally controlled transmitter and receiver circuits.

Abstract: A surveillance system for maintaining continuous vigil as to seismic energy generating disturbances in and around an underground mine, such system being one of permanent installation which in combination with central data processing apparatus provides a continuous data output indication of certain mine activities. The system utilizes a plurality of permanently installed, underground geophone sensors each in communication via particular ACC circuitry and signal processing circuitry to provide input through an interface logic network to a central computer equipment programmed to determine disturbance locations, certain intensities, time duration and the like.

Abstract: A system for maintaining a continuous log of activity in and around an underground mine wherein seismic energy in the area is continually monitored, processed and classified into meaningful relative data indications; and which system further includes selectively deployable seismic energy monitoring equipment providing more specific data in the event of mine catastrophy. This system utilizes permanently disposed seismic energy detectors and/or emergency detectors placed in accordance with the particular exigency, and detected seismic energy return is continually processed to maintain a data log indicative of general type and location of mine activity, with particular capability for isolation of unusual seismic events by comparison with statistical data constraints of predetermined character.