Synchronized acoustic source

Abstract

The current invention is an apparatus useful for generating seismic waves with an enhanced signal to noise ratio. The enhanced signal is produced at a fundamental resonant frequency, and multiples thereof, by producing a near zero acoustic pressure condition around and beyond each end of the apparatus having an intermediate acoustic source. Such a near zero acoustic pressure condition is established preferably by either (1) using two end acoustic sources to produce a destructive interference effect with the acoustic output of a third acoustic source postioned therebetween, or (2) using two active or passive end acoustic capacitors or resonators to produce a near zero impedance condition at each end of the apparatus. The enhanced signal may be produced over a range of frequencies, including both resonant and nonresonant frequencies, by creating a high impedance condition experienced by the intermediate source and hence a high acoustic pressure around the intermediate region of the apparatus. Preferably this high impedance condition is generated using one or more internal acoustic capacitors or resonators, with each being positioned between the intermediate acoustic source and an end acoustic source or capacitor or resonator, respectively. The apparatus can maintain the high impedance or resonant condition up to a frequency which is about two times the resonance frequency between the intermediate source and each internal acoustic capacitor.