Abstract: A low cost easily installed and reliable weather seal for the nozzle throat of a solid propellant rocket motor which uses an aft end ignition system. The igniter cartridge, known per se, which is located in the throat of the rocket motor is provided with an elastomeric O-ring in the base of the cartridge thus sealing the gap between it and the inside surface of the exit cone of the nozzle. This structure not only provides an effective weatherseal but also provides a convenient means of positively retaining the igniter cartridge in place.

Abstract: The invention disclosed is a surgical dressing, particularly useful for the protection of wounds during the healing process. The dressing comprises a blend of gelatin and chitosan in a weight ratio of about 3:1 to 1:3 and a compatible plasticizer in an amount of 0-40% w/w based on the combined weight of gelatin and chitosan.

Abstract: A system for monitoring the integrity of a cable, for example a cable for towing a variable depth sonar body through the ocean, is described. Such a cable comprises a core of electrical wires surrounded by load bearing wires which are secured to the sonar body through a terminator. For various reasons cracks can appear in the load bearing wires and in extreme cases one or more of the wires may break. The monitoring system includes a transducer located near the terminator where the wires are most likely to crack or break and acoustic emissions caused by the incidence of cracks or breaks are picked up by the transducer. The resulting electrical signals are amplified and passed up the electrical core of the cable to the towing vessel where they are processed. Novel aspects of the system are the water coupling between the location of the cracks or breaks and the transducer and special processing circuitry which enables breaks, cracks and electrical noise to be distinguished from each other.

Abstract: A microstrip antenna is disclosed consisting of a flat metallic patch spaced from the ground plane. To increase the bandwidth of the antenna a pair of varactor diodes are provided positioned at opposite sides of the patch and connected between it and the ground plane.

Abstract: An optical fiber hydrophone system in which a single optical fiber is used for all of the acoustical sensors in the system. A signal source and detector provides an optical signal in selected form, such as continuous or pulsed and detects and extracts an identifiable output signal. Each sensor is in the form of a sensing portion of the single optical fiber. Each sensing portion includes two optical reflectors separated one from another by a predetermined length of said optical fiber. Variations in acoustical pressure incident on the sensing portion causes a change in the predetermined length. This causes reflected portions of the optical signal to interfere with one another. Such interference is detectable for extraction of the identifiable output signal. In one form each sensing portion has two terminal branches of a mechanically deformable material, deformable in response to the fluctuations in acoustical pressure.

Abstract: An underwater transducer in which a ring of piezoelectric ceramic elements vibrates radially in response to an applied voltage. Spacer elements formed of steel are placed between pairs of ceramic elements and used to couple the ring movement to convex diaphragms. Each diaphragm is formed with radially extending fingers, which attach to the spacer elements. A water bladder assembly within the transducer forms a passive internal pressure compensation system. Preferably, the water bladder assembly is attached to the ring in a manner that mechanically decouples the bladder assembly from the ring.

Abstract: A sampling spectrum analyzer provides instantaneous continuous wideband spectrum analysis to allow RF signals occurring simultaneously and spaced within the band to be displayed. An input signal is split and each resulting portion is passed down a tapped delay line, with samples at the taps of each line being processed by separate arithmetic units. The output of each arithmetic unit is applied to the taps of output delay lines which are similar to the input delay lines. Each arithmetic unit weights the input samples with a set of coefficients and sums the resulting signal in a prescribed manner, thus transforming the signal into the frequency domain, according to a discrete Fourier transform. The resulting sums are the real and imaginary terms of a signal which are vectorially added, resulting in a signal which is fed to the ordinate of a display having a swept time base representing frequency.

Abstract: A method and apparatus for frequency conversion comprising sampling an input signal having a first frequency with first time delays between samples in an input delay line, and distributing the samples of the input signal in sequence to an output delay line with different time delays between samples than the first time delays, to generate an output signal of different frequency than the input signal.

Abstract: A tubular structural element comprises a tubular body made of a fiber reinforced composite material having reinforcing fibers embedded in a matrix. The fibers are one of carbon, berylium, boron, glass, metallic or non-metallic, or a hybridized combination of the same. The tubular body has projections interiorly thereof which are integral therewith, and are of the same or another fiber reinforced composite material. The reinforcing fibers in the body are oriented in mutual stress transmitting relation, preferably circumferentially in the tubular body, and longitudinally in the interior projections. In making the tubular structural element, the fiber reinforced composite is introduced into each channel formed in a mandrel. The channels extend generally longitudinally of the mandrel, and optionally may also be spirally or helically oriented. Additional composite material is then overlaid generally circumferentially on the mandrel, to a desired thickness.

Abstract: An optical coupler for a fiber optic communication system, which couples one band of wavelengths out of the fiber while allowing others to be carried further. This allows wavelength division multiplexing of different signals within a single fiber. The preferred embodiment of the invention is comprised of a waveguide having aperiodic corrugations in one wall and a Fabry-Perot type resonator enclosing the waveguide around the corrugations with its axis transverse thereto.

Abstract: Disclosed are optical data bus configurations for interconnecting terminals so that any terminal can communicate with any other terminal. It is known to do this by connecting terminals serially using two trunk optical fibers and to connect terminals together in a star configuration using a single transmission star or reflection star. The serial network is limited by optical loss while the star network requires more optical fiber and is more costly. Disclosed is a serial bus which uses six fibers arranged in two groups of 3 each, the groups conducting light in mutually opposite directions. A transmitting means in each terminal is coupled to two of the fibers in each group and terminals adjacent any one terminal are connected to a different two fibers than the one terminal. Another arrangement disclosed uses hybrid reflection-transmission star couplers. Terminals can be connected to reflection ports of the hybrid couplers, while the couplers can be interconnected by the transmission ports thereof.

Abstract: A system for locating a transmitter in an unknown location comprising apparatus and the method of receiving transmitted signals from said transmitter at the separated locations, demodulating the transmitted signals, performing a Fourier transformation of each of the demodulated signals to represent them as complex functions of frequency, while performing a complex division of pairs of the signals represented as complex functions of frequency, to obtain signals represented by the phase differences between pairs of signals as functions of frequency, and determining from the difference in phase between pairs of signals as a function of frequency the time differences existing between the said pairs of functions. From these time differences the position of the origin of the transmitted signals are determined and displayed.

Abstract: Known electronic countermeasures systems have difficulty handling some modern radar signals, for example frequency agile, frequency sliding or frequency coded signals. The invention disclosed overcomes the problems of the prior art by using an analog frequency dividing system to virtually instantaneously down-convert received signals in octave steps and in octave stages into the frequency regimes associated with the operation of processing devices, such as analog to digital converters, digital logic devices, surface acoustic wave devices, and charge coupled devices. Those processed signals which are selected for retransmission, perhaps in a modified form, are then up-converted into the region of the received signal by the appropriate number of stages of frequency multipliers.

Abstract: An omni-directional type passive antenna in which the response pattern is a close approach to the ideal of a hemisphere. The system includes an antenna having an antenna axis extending in the direction of highest antenna sensitivity, and a first surface which is a surface of revolution swept out by a part of a parabolic curve rotated about the antenna axis, the axis of the parabolic curve being inclined at an angle in the range of about 70 to 80 degrees to the antenna axis with the focus of the parabolic curve substantially on the antenna axis. A first set of electrically isolated dipoles is mounted on the surface and all are similarly oriented such that they lie only along edges of axial planes of the antenna.

Abstract: A microwave frequency divider operable in 8-16 GHZ range. A circuit resonant at a subharmonic frequency is formed by a pair of input microstrip transmission lines coupled to a pair of output microstrip transmission lines. Each input line is terminated by a varactor diode. The input signal is supplied to the resonant circuit by a pair of microstrip lines functioning as a two stage quarter wave transformer. A metal plate positioned over the resonant circuit and closely spaced from it functions to extend the upper end of the frequency range. A bias supply line for the diodes has a portion passing through a resistive foam block to remove spurious signals. A movable stub is positioned along the bias supply line to extend the lower end of the frequency range.

Abstract: An apparatus for and method of monitoring a battery for faulty cells by comparing a pair of input voltages from respective groups of the cells to provide an output signal corresponding to a difference between the input voltages, which initiates an alarm signal when the voltage difference exceeds a predetermined value. To compensate for normal differences between the voltages, the relative magnitudes of the input voltages may be adjusted before the input voltages are compared.