Seismic parameter measurement method and apparatus

Claim 1

Seismic parameter measurement apparatus, comprising; an electrodynamic geophone comprising a coil and a sharpened portion adapted to be driven into the ground in an area to be tested for the seismic parameters thereof, said coil being connected to an electronic circuitry case by means of an electric cable, said case including a microammeter, an on-off switch and a gain control knob mounted on the top surface thereof, said cable connecting within said case to the input of a solid state bandpass preamplifier comprising three cascaded transistor amplifiers adapted to preamplify seismic signals generated in said coil of sad geophone, said preamplifier comprising a high pass filter, the output of said preamplifier being connected to an emitter-follower circuit adapted to function as a buffer, the output of said emitter follower being applied to an integrated circuit amplifier through a low-pass filter, said integrated circuit amplifier comprising a negative feedback circuit, a diode rectifier bridge circuit connected to the output of said integrated circuit amplifier, said microammeter and a capacitor being connected across the output of said bridge, the ground return circuit of said diode bridge being arranged to provide operating bias voltage for said integrated circuit amplifier, and a battery within said case arranged to provide B+ operating voltage for said preamplifier and integrated circuit amplifier.

Claim 8

A method of determining the optimum placement of an array of geophones to surround an area to be protected from intruders on foot comprising the steps of: implanting an electrodynamic test geophone in the ground in said area to be protected, said geophone being undamped and the coil of said geophone being connected to a solid state preamplifier and amplifier connected in cascade; amplifying the seismic signals; rectifying the signals by means of a bridge circuit comprising four diodes; displaying the seismic signals on a microammeter, the ground return circuit of which includes a capacitor which functions as part of an integrator in conjunction with the forward resistance of said diodes, the time constant of said integrator being chosen to permit said microammeter to respond to step frequency signals without appreciable integration, to determine the presence of seismic noise in the area; if said seismic noise is below a predetermined value, determining the proper spacing of said geophones in said array of geophones by generating seismic signals at various distances from said test geophone; and, coordinating the readings on said microammeter with the positions of the signal generator.

Claim 9

A method of determining the optimum placement of an array of geophones to surround an area to be protected from intruders on foot comprising the steps of: implanting an electrodynamic test geophone in the ground in said area to be protected, said geophone being undamped and the coil of said geophone being connected to a solid state preamplifier and amplifier connected in cascade; amplifying the seismic signals; rectifying the signals by means of a bridge circuit comprising four diodes; displaying the seismic signals on a microammeter, the ground return circuit of which includes a capacitor which functions as part of an integrator in conjunction with the forward resistance of said diodes, the time constant of said integrator being chosen to permit said microammeter to respond to step frequency signals without appreciable integration, to determine the presence of seismic noise in the area; if said seismic noise is below a predetermined value, determining the proper spacing of said geophones in said array of geophones by generating seismic signals at various distances from said test geophone; and, coordinating the readings on said microammeter with the positions of the signal generator.