Wide band frequency shifter in variable amounts

Abstract

2. A sonar decoy system for receiving and retransmitting any interrogating signal throughout a wide band of frequencies, said system comprising; a sonar receiver with a receiving hydrophone; a sonar transmitter with a radiating transducer; a resolver with two orthogonal field coils, and a mechanically rotatable rotor coil; a first and a second network coupled between the output of said receiver and, respectively, said two field coils, said networks each comprising a balanced four-terminal, four-sided bridge with each input terminal coupled, respectively, to the two output terminals through tunable resonant and anti-resonant circuits, said circuits of the networks being differently tuned to shift the phase of the wide band frequencies of one network substantially 90 electrical degrees with respect to the phase shift of the other network for producing a rotating magnetic field in said field coils throughout said wide band; a reversible variable speed motor coupled to said rotor coil to rotate said rotor coil with, or in opposition to, the direction of rotation of said magnetic field to induce in said fields coils any frequency throughout said wide band of frequencies and increased or decreased depending, respectively, on the direction of rotation of said motor and depending on the speed of said motor, and means for coupling said rotor coil to said transmitter.

Dependencies are inferred from the claim text.