Abstract: A Sonar decoy system receives an interrogating pulse from an energy source nd then distorts, elongates, amplifies, and retransmits the pulse to simulate an echo of that pulse rebounding from the various reflecting surfaces of a moving submarine. To refine the allusion of an actual echo, a portion of the pulse signal is circulated and recirculated through a delay line several times, and then reinserted into the outgoing signal to contribute random additions to and phase cancellations of the various frequency components of the signal.

Abstract: A crossover network is coupled to each transducer in an array of acoustic ansducers, each transducer having a different frequency band, and all of the crossover networks being coupled in parallel to a single driving amplifier. Each crossover network includes a network inductance connected in parallel with a transducer capacitance to form a parallel LC circuit, the resonant frequency of such circuit being equal to the resonant frequency of a transducer RLC series circuit. The network inductance of each network is coupled to the amplifier in series with a driver inductance and a driver capacitance, which are respectively equal to the inductance and capacitance of the RLC series circuit of a transducer.

Abstract: 2.

Abstract: 1. A system for simulating wave reflections from an irregular-shaped moving bject which has been illuminated with energy of frequency F, said system comprising;a receiver (10) for said frequency F;a generator (14) of white noise voltage;means (13) for amplitude modulating frequency F with said white noise voltage to generate random bursts of frequency F;a radiating transducer (11);a bandpass filter (18) having a passband including said frequency F, the output of said filter being coupled to the input of said transducer, and the input of said filter being coupled to the output of said modulator means (13) to radiate said random bursts of frequency F;a second signal path between said modulator and filter including a time delay network (30) for randomly distorting the radiated bursts.

Abstract: 1. In a submarine simulation sonar beacon adapted for predetermined maneuing under water, a hull having a forward and an aft transducer for receiving an acoustical signal within said water, means disposed in said hull connected to said forward and aft transducers for comparing the time relationship of arrival of said acoustical signal thereat, means coupled to said comparing means for generating an output signal having a characteristic which is a function of said time relationship, means coupled to said generating means for amplitude and highlight modulation of said output signal, and transmitting transducer means mounted on said hull and coupled to said last mentioned means for broadcasting said modulated signal through said water.

Abstract: An apparatus for driving a reactive load, comprises a plurality of N multnput elements N .gtoreq. 2, connected in parallel, capable of amplifying a band of frequencies. Two inputs of each element can be connected to sources of direct-current voltage. Each circuit element and elements connected to its inputs define a circuit stage. N means, each means connected to at least one of the inputs of the circuit elements, are capable of equalizing the gain of each of the N stages within a prescribed percentage. A transformer having N primary, input, windings and one secondary output, winding, is connectable to the load. Each of the N primary windings have their inputs connected to one of the inputs of the circuit elements. The transformer is so designed that its impedance, usually inductive, as seen from the load, balances the capacitive load, to be connected to it, over the bandpass of interest.

Abstract: The closed feedback loop of an oscillator contains a network (i.e. a resot circuit or filter) which has a distinct phase-frequency characteristic so as to cause an overall in-phase condition. In the subject feedback loop, shifting the phase of the feedback wave in the filter, the frequency of the oscillator will shift due to its double heterodyning circuit to reestablish a net zero phase shift around the loop. This oscillator is particularly adapted to shift a sonar signal frequency to simulate true doppler shift where this shift is a fixed percentage of the frequency.