Abstract: Bicycles are adapted to be combined by removing the front wheel of a trailing one of the bicycles and attaching the front fork ends to the rear axle of a leading one of the bicycles, resulting in a three-wheeled tandem bicycle with two drive wheels. To allow for relative pitching motion of the coupled bicycles, the attachment includes bearings. Each bearing may include a brass sleeve over the rear axle and a separable end cap on each fork end, the cap held to the fork by screws. The sleeve is longer than the width of the fork end to prevent binding. Each fork includes a yaw-correction torsion spring that resists angular rotation of the handlebars of the trailing bicycle relative to the rear axle of the leading bicycle. The yaw-correction spring may include a flat tine portion of the fork. The tine preferably slides into the upper part of the fork in a slot.

Abstract: A proximity fuze system having a plurality of spatially disposed energy dctors, the response patterns of which overlap in such manner as to form an energy response "fence" for detection of an intruding object within a certain area. An explosive charge is also included in the system for disabling or destroying said intruding object, and a plurality of memories and gates are effectively connected between said detectors and explosive charge to effect the detonation thereof whenever said object is within such lethal range as to be sensed by predetermined pairs of said detectors.

Abstract: A doppler compensated sonar system is disclosed as including a transmitter nd a receiver. The receiver of the disclosed preferred embodiment is a single channel receiver which incorporates a mixer and a narrow pass band filter connected in series therein. A phase lock loop of the negative feedback type is connected between the control input and the output of said mixer which effectively determines the occurrence of any doppler effects being processed in said receiver channel and compensates therefor by appropriate adjustment of the frequency of the signal supplied to the control input of said mixer, thereby causing the remainder of said receiver channel, including said narrow band pass filter, to process received target signals without any doppler effects being present therein.

Abstract: A radiant energy detector having a pair of receiving transducers, a pair of ariable gain amplifiers connected to said transducers for amplifying the outputs thereof different amounts, a subtract circuit for producing a signal representing the difference of said amplifier gains, a Schmitt trigger which is triggered by said difference signal whenever it exceeds a predetermined value, and an And gate connected to the outputs of said pair of amplifiers and the output of said Schmitt trigger for producing a utilization signal whenever all thereof occurs simultaneously.

Abstract: An electroacoustic transducer having a truncated hemispheric propagation or esponse pattern is disclosed. The transducer comprises an assembly of fish-bone shaped piezoelectric elements, each characterized by a plurality of rod portions extending from a spine portion. The assembly is pivotally mounted within a liquid filled acoustic window means.

Abstract: A sonar system is disclosed having signal analyzing circuitry rendering the ystem responsive to objects of a predetermined size. The signal analysis is accomplished by a spectral analysis of the echo signals returned from the objects. In particular, the relative height of adjacent side lobes of echo signals energy returned to the sonar are compared to indicate the size of the object reflecting the signal.

Abstract: A continuous wave, doppler sonar has an underwater towed portion including projector disposed vertically displaced from a multi-element receiving array. Received CW signals are processed for spillover elimination and subjected to phase lock loop tracking filters for reverberation and target doppler prior to target signal detection, thresholding, multiplexing and transmission to the towing portion. The target signals are distributed as to azimuth, recirculated in a memory, and reiteratively displayed in PPl format, with periodic updating.

Abstract: A doppler compensated sonar systems is disclosed as containing one or more ata processing channels connected through a multiplexer to a like plurality of piezoelectric elements in a reversible electro-acoustical transducer. Each channel thereof includes a transmitter and a receiver, the latter of which includes signal perfecting circuitry and a pair of effectively series connected phase lock loops constituting reverberation and target doppler tracking filters, respectively. Hence, each of said channels effectively process received target signals without any adverse doppler effects being present therein which are then, in turn, read out by any suitable video display. When mounted on a fast moving vehicle, the subject doppler compensated sonar system optimizes the avoidance of hazardous or other objects that may occur in the path thereof.

Abstract: 1. A transducer comprising in combination,a plurality of piezoelectric discs arranged along a common axis of revolun in the order of increasing diameters in the aft to forward direction,resilient means interposed between each of said piezoelectric discs for the support thereof with a predetermined relative degree of freedom of movement,means effectively connected to the end ones of said piezoelectric discs for the urging thereof toward each other by compressing the resilient support means interposed therebetween and in such manner as to maintain the entire plurality thereof in a predetermined unitary geometrical configuration, andmeans connected to each of said plurality of piezoelectric discs for the driving thereof in electrical parallel.

Abstract: Relative phase and sensitivity characteristics of individual transducer eents in a long acoustic array are determined by sequentially positioning a transmitting element in predetermined spaced relation to each array element by means of an array holding member and a trough-like spacing member that contains a known transmission medium, driving the transmitting element with a test frequency input signal that is pulsed at a predetermined repetition rate, gating the output signal from the array element under test to an oscilliscope for phase comparison with an adjustably phase shifted version of the input signal, and measuring amplitudes of both input and output signals.