Abstract: A method and apparatus are used in the acquisition of data by ground-penetrating radar, wherein the signals thus obtained are input to a pre-amplifier which contains filtering component such as an anti-aliasing filter. The base gain of the system is switch selectable and electronically adjusted to bring the input signal to between one half and full scale on an analog to digital converter input. The converted digital value has a resolution of fifteen bits for processing.

Abstract: A method and apparatus for maintaining a second elongated hole axis substantially parallel to a previously bored horizontal hole axis which entails inserting a seismic signal generating apparatus into one hole and a seismic signal receiving apparatus into the other hole. The seismic receiver includes apparatus for moving it along the axis, for maintaining the receiver substantially parallel to the gravitational bottom of the hole, and for moving the receiver a predetermined distance from the borehole wall which is adjacent the borehole containing the seismic signal generating apparatus. Apparatus for observing the detected signal is located outside the borehole.

Abstract: A method and apparatus for construction of a seismic vibrator control signal which comprises manually selecting sweep parameter data values for starting frequency, ending frequency, sweep time and taper time and inputting to an addressable storage medium. Thereafter, determining for each of a plurality of sample points throughout the sweep time, the sweep rate of change per sample point and the accumulated frequency value per sample point, and outputting in real time the digital sweep values for each successive sample point, and subsequently converting and smoothing said successive digital sweep values to an analog control signal of the selected frequency, relative amplitude and duration of sweep length.

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: 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 method of induced polarization geophysical surveying which derives meaningful parameters relative to the subsurface strata in both time domain and frequency domain for comparison and/or deductive data compilation and graphic depiction. The system includes a current source as energized by an input wave generator providing an input signal of predetermined frequency content, amplitude relationship and duration; in addition, a plurality of energy receiving detectors are utilized in equi-spaced array such that differential electrical measurement between successive detectors may be gained during each single input energy operation. Such differential electrical measurements are further susceptible of cross correlation relative to the input current signal to provide increased signal-to noise differentiation with respect to usable induced polarization resultant values.