Secure sonar communication system

摘要

A secure sonar communication system for transmitting and receiving intelligence signals within an aqueous medium comprising in combination means for generating an electrical pseudo random noise signal within a predetermined bandwidth, means connected to said pseudo random noise generating means for selectively driving same at one of a plurality of predetermined frequencies, keying oscillator means adapted to selectively produce an output of one of a plurality of predetermined frequency signals, a balanced modulator means coupled to said pseudo random noise signal generating means and said keying oscillator means for mixing the output signals therefrom, bandpass filter means connected to the output of said balanced modulator means for passing the upper sideband thereof, means for receiving an electrical pseudo random noise signal, transducer means, said transducer means being capable of broadcasting acoustical energy upon excitation by the upper sideband from the aforesaid bandpass filter means and in proportion thereto and for producing an electrical pseudo random noise output signal in proportion to a received acoustical pseudo random noise signal, and means connected to the output of said bandpass filter means and the input of said electrical pseudo random noise signal receiving means for selectively connecting same to said transducer means during broadcasting and receiving operations respectively.