Abstract: A power efficient, acoustical Helmholtz resonator foghorn including a plurality of electrical emitters, some of which are redundant, arrayed at one end of a blocked tube with a plurality of exhaust ports located therein surrounded by a standoff tubular member. The foghorn tuned to provide a high pitch thus providing a compact horn having an acoustical path capable of producing an exceptional wavelength in a generally concentric horizontal sound propagation the horn configurable for use as either a one-half mile or two mile marine navigational aid for offshore structures, buoys, and the like.

Abstract: Disclosed are method and apparatus for producing electric waveform driver signals for exciting acoustic emitters such as foghorns, wherein the frequency and amplitude of the signals are readily variable to match the input requirements of the respective drivers of the acoustic devices. In disclosed embodiments of a signal generator according to the present invention a coupling circuit outputs the driver signal through an array of field-effect transistors.