Abstract: A light emitting diode with emission wavelength in the 1.06.mu.m region suitable for use with the 1.06.mu.m transmission window in optical fibers. The diode is fabricated by liquid phase epitaxial growth of p and n type InAs.sub.x P.sub.1-x layers on InP substrates.

Abstract: Apparatus is provided for preventing premature, manual operation of a parute activated during ejection by airload tensional forces on the parachute container and harness riser strap system, which is accomplished by slidably mounting the ripcord handle assembly with respect to the riser strap.

Abstract: A method and means for coupling information or signal power into or out of iber optics for integrated optical waveguides. The coupling consists of selectively doping with impurity ions such as rare earth or transition metal ions which are excited to fluorescence within the waveguide by the frequency of the transmitted carrier wave. The fluorescent emission is then detected at right angles to the fiber using conventional photodetectors and amplifiers.

Abstract: A coupler for connecting a radiant energy transmitting element to a radiant nergy receiving element which utilizes a specially designed lens for each element, said lenses having spherical convex segments positioned in close face-to-face relationship so that the radiant energy emerging from the transmitting element is treated as a point source which is sequentially defocused and focused by means of the lenses onto the receiving element to minimize refraction and other losses and to insure maximum coupling efficiency.

Abstract: Method and apparatus for detecting tunnels beneath an area of the earth's rface wherein an oscillator couples a current into a linear conductor at the earth's surface to generate a magnetic field in the earth beneath the area. Phase angle measuring means measures phase difference between the vertical and horizontal components of the magnetic field at selected points along a line parallel to the linear conductor to detect abrupt changes in earth resistivity, changes in resistivity indicating the presence and horizontal position of a tunnel.

Abstract: A serial to parallel converter receives a succession of digital bits in serial form comprising discrete data formats and control formats through its input terminal, which is coupled to a data shift register and to a control shift register. When a data format is coupled into the input, a register enable circuit enables the data register to load and convert sets of changeable data bits, comprising part of the data format, to parallel form. When a control format is coupled into the input, the register enable circuit enables the control shift register to convert sets of changeable control bits, comprising part of the control format, to parallel form. One of the changeable bits in every control format immediately followed by a data format comprises an incoming data indicator.

Abstract: Improved thermal coupling for a fragile member having a low tolerance to hanical stress is provided by use of thin sheets of common household aluminum foil having impressed thereon a uniform pattern of indentations. The indentations create raised projections which resiliently support the fragile member by the application of a minimum pressure to provide a uniform, non-varying contact therebetween, thereby enabling the mechanical motion therebetween to be absorbed without damage to the fragile member.

Abstract: A method and apparatus for data compression which utilizes a random walk ough Pascal's triangle which is directed by the incoming random source sequence. The random walk starts at the apex of Pascal's triangle and proceeds downward according to an algorithm until it terminates at a boundary which has been constructed in such a way that the encoding of each source sequence can be accomplished in a fixed number of bits. The fixed-length encoded block consists of a prefix to determine the boundary crossing point in Pascal's triangle and a suffix which represents the encoded form of the input sequence relative to that starting point. Theoretically optimal entropy encoding is achieved by this method.

Abstract: A data switch which can rapidly configure and reconfigure multiple channels between computer equipments for digital data transmitted at a rate in excess of 10 megabits per second. The switch includes a switch matrix connected between an input and an output voltage level buffer, a mini computer, and control circuitry. The switch matrix comprises three stages, each containing 256 switching elements which are active integrated circuit elements each having 16 data inputs and one data output. A channel is configured through the switch matrix when one switching element in each stage responds to a control signal to couple one of its data inputs to its data output, over a million different channel configurations being possible. Each switching element is heavily grounded to effectively eliminate cross talk between channels and each data input line of each switching element is provided with an amplifier to improve time fidelity of the switch.

Abstract: A low loss tuneable RF filter including a parallel plate variable capacitor nd a helical resonator within an extension of the resonator shield. The capacitor stator is supported on an insulator above one end of the helix while the rotor is mounted between the walls of the resonator shield. The rotor plates are wider than the stator plates by about 20%.

Abstract: An apparatus for estimating the mean level of a stochastic process such as ould be observed at the output of a radar, communications, or sonar receiver and for using the mean level to provide a threshold with which possible signal samples are compared to determine the presence or absence of the signal. The estimated mean level is used in lieu of a priori information when it is unreasonable to assume that the characteristics of the stochastic process are known. A first order recursive filter receives signal samples and provides an output which is proportional to the mean of the stochastic process. The output of the first order recursive filter Y.sub.n is multiplied by the factor T such that the product TY.sub.n is a threshold quantity which is compared with the input signal samples X.sub.n. When X.sub.n exceeds TY.sub.n an output is indicated.

Abstract: A single antenna array having a phase shifter at the input of each antenna lement and fed by a multifrequency input for simultaneously generating at least two beams. When the different excitation frequencies are simultaneously inputted into the phase shifters, a separate phase increment is introduced into each radiator for each frequency. The result is a separate beam output from each frequency input, the beams being generated simultaneously but at different beam pointing angles.

Abstract: A navigation aid comprises two transmitters transmitting signals in the LF/MF range (250 kilohertz-490 kilohertz) and a receiver indicator for receiving each of the transmitted signals, translating them to a common frequency, and indicating the phase difference at any given position. Frequency stablizing means are coupled to each transmitter to stabilize the frequency of each transmitted signal and to prevent the differential frequency error from exceeding a selected limit.

Abstract: An optical waveguide arrangement operates in the manner of an interferometer to provide modulator and/or switching functions. Two optical waveguide branches having a common connection diverge along a substantially coextensive distance and reconverge to provide first and second light paths of identical optical length. Conductive electrodes are disposed contiguous to at least one of the optical waveguide branches and are connectable through a controlling switch to a source of electrical energy for producing an electric field across the energized electrodes. In the absence of such electric field, light energy entering the two optical waveguide branches will propagate along identical optical path lengths and recombine constructively at the reconvergence of the waveguide branches.

Abstract: A wide angle narrowband optical filter is provided by an assembly in which a body member supports multiple absorption materials in a common optical path. Each of the multiple absorption materials contributes toward narrowing the spectral bandwidth region permitting transmittance of light energy. A bandpass glass color filter restricts light transmission to a relatively broad spectral range of approximately 250 nanometers and a selected coumarin dye material in solution used with a second solution of a selected rare earth material narrows the spectral range of transmittance. In a preferred embodiment an interference filter further narrows the transmitting bandwidth to approximately 12.5 nanometers at FWHM (measured at Full Width Half Maximum) in the spectral region which is desirably coincident with the wavelengths of light energy best transmitted in ocean waters.

Abstract: A system for obtaining the range and bearing of the location of any radar transmission with a minimum of received data (one pulse). Three receiving systems spaced apart from each other receive signals from the radiating source. Solving three simultaneous equations for circles using the location of each receiving antenna as the center of three circles. The point of intersection of the three circles is the location of the radiating source.

Abstract: A switching system for rapidly configuring transmission paths between comer equipments for high speed digital information in parallel form couples the input of a parallel-to-serial (P/S) converter to the output of each equipment providing information and the output of a serial-to-parallel (S/P) converter to the input of each equipment receiving information. A digital switch rapidly configures information transmission channels between its inputs and outputs in response to instructions from a configuration control. Each switch input is coupled to the output of a P/S converter, and each switch output is coupled through a switch output lead to the input of an S/P converter. A clock provides a periodic clock signal to each P/S converter through an adjustable delay control and to each S/P converter through a clock lead, wherein the electrical lengths of the switch output lead and clock lead coupled to the same S/P converter are equal.

Abstract: An encoding system wherein digital information comprising data, clock, and artitioning components is coupled to an encoding means comprising interconnected digital elements to generate a serial encoded signal having the encoded data, clock, and partitioning components inherent in the structure of the encoded signal. The encoded signal may be stored in a magnetic record/reproduce system and subsequently coupled to a decoding means comprising interconnected digital elements to recover the data, clock, and partitioning components of the original digital information.

Abstract: A portable seating bench for positioning subjects for anthropometric measments provides a flat surface upon which a subject may be seated, the flat surface comprising a part of a containing means. Supporting structure is provided to support the flat surface and a subject seated thereon and to support or otherwise position the feet of the subject while a set of anthropometric measurements are made with portable measuring devices, all such support structure and measuring devices being of such dimensions that they may be contained within the containing means for transport or storage.

Abstract: A millimeter wave amplifier having broadband characteristics in which a G diode or other two terminal negative resistance device having an integral heat sink is center mounted in a reduced height waveguide. The heat sink is attached to a mechanism for selectively adjusting its penetration into the waveguide cavity. The introduction of the heat sink into the waveguide cavity creates a discontinuity to the propagation of energy which causes localized waveguide modes other than the dominant mode to exist. The adjustable position of the heat sink allows the reactance due to the introduction of these modes to be variable, proper adjustment resulting in the cancellation of the parasitic reactances inherent in the packaged negative resistance device.