Seismic reflection amplifier

Claim 1

IN A SEISMIC GEOPHYSICAL EXPLORATION SYSTEM FOR DETERMINING THE COEFFICIENT OF REFLECTION ALONG A SUB-SURFACE LAYER, THE IMPROVEMENT COMPRISING AN ELECTRONIC AMPLIFIER HAVING HIGHLY LINEAR CHARACTERISTICS OVER A RANGE OF SIGNAL FREQUENCIES FROM ABOUT 2 TO ABOUT 500 CYCLES PER SECOND, SAID AMPLIFIER COMPRISING A DIRECT COUPLED BALANCED TRANSISTOR AMPLIFIER OF THE PUSH-PULL TYPE, EACH TRANSISTOR OF SAID TRANSISTOR AMPLIFIER HAVING A BASE, EMITTER AND COLLECTOR ELECTRODE, SAID AMPLIFIER COMPRISING A NONREACTIVE INPUT ATTENUATOR AND HAVING A LOW FREQUENCY TRANSFORMER AT THE INPUT AND THE OUTPUT THEREOF, A DEGENERATIVE FEED BACK CONNECTION ON EACH SIDE OF SAID BALANCED AMPLIFIER, EACH FEED BACK CONNECTION EXTENDING FROM COLLECTOR TO BASE OF RESPECTIVE TRANSISTORS ON EACH SIDE OF THE BALANCED AMPLIFIER, SAID FEED BACK CONNECTION INCLUDING A SHORT CIRCUIT CONNECTION CONNECTED BETWEEN THE FEED BACK CONNECTIONS FOR ELIMINATING FEED BACK OF DIFFERENTIALLY AMPLIFIED SIGNALS.