Abstract: Optical fibres are protected against stress corrosion by first coating the ptical fibre with a primary coating of an ultra violet curable cis, trans fluoropolyolacrylate in which the modulus is reduced by eliminating about 25 percent of the pendant ester groups, curing the primary coating, applying a secondary coating of a high modulus heat curable fluoroepoxy or a high modulus UV curable cis trans fluoropolyolacrylate over the primary coating and curing the secondary coating.

Abstract: An adaptive interference cancelling system for multibit spread spectrum noise codes wherein a plurality of users in a mobile subscriber access system each operates with a different noise code. Each user receives a composite signal which includes a desired noise coded signal from another user plus any unwanted interference noise coded signals from other like users in relatively close proximity. The RF demodulator or front end section of each user receiver is coupled to a bank of matched filters which selectively detect and identify any interfering codes. These interfering codes are then regenerated devoid of the desired signal to provide a coherent replica of the interference signal. The received composite signal and the coherent replica of one or more interference signals are applied to individual signal subtractor circuits which operate to cancel the interfering noise coded signals leaving the desired signal to be subsequently matched filter detected free of interference from other users.

Abstract: Twin lead transmission lines are positioned in close coupling relationship o linearly polarized and planar arrays of antenna radiating elements to provide a self contained instantaneous antenna test and measurement system. Near field energy from the transmission lines is coupled to the transversely arranged antenna dipole elements to permit testing without degrading antenna performance. Signals induced on the radiating elements are of uniform amplitude and linearly changing phase equivalent to those of a far field plane wave. Various tests such as antenna failure and performance characteristic measurements, including gain, pattern and phase difference, can be made automatically. A balanced power divider distributes RF power equally to the twin lead transmission lines and a system processor controls phase shifter scanning elements and analyzes the various output parameters to provide the desired test and measurement information concerning the selected array of dipoles and components.

Abstract: A dielectric waveguide of rectangular cross-section has periodically spaced, transverse slots in its upper surface. When traveling waves of varying millimeter wavelength frequencies are applied to the waveguide, the slots perturb the waves resulting in radiation having a main lobe that scans as the frequency changes. The antenna is made rigid by the use of a dielectric support.

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: A method for constructing and the resulting structural configuration of an nput coupler for a concentric core optical fiber comprises removing the outer protective material of a concentric core optical fiber to expose the outer core back a predetermined distance from the end which includes the intermediate protective material or cladding and the inner core. A plurality of single core optical fibers are stripped so that their respective cores are exposed whereupon they are bonded to the exposed outer core by a transparent index matching epoxy, which bonding is located at the transition region where the exposed outer core begins and the outer cladding ends. The outer end of the concentric core fiber element including the intermediate protective material and the inner core is cleaved and at least one other single core optical element is cleaved and bonded in end to end abutting relationship with the inner core by transparent index matching epoxy.

Abstract: A meander line slow wave structure mounted on ceramic bars for a microwave evice such as an injected beam crossed-field amplifier includes frequency selective attenuator means which will preferentially attenuate waves at frequencies near and within the stopband of the slow wave structure by the placement of side absorber bars of attenuating material adjacent to the outer side surfaces of a plurality of meander line finger segments. The frequency selective absorber material, in its preferred form, comprises a beryllia and silicon carbide ceramic composition which additionally adapted to accommodate metallic absorber top plates, nichrome films, and slotted side ring configurations.

Abstract: The structure of a thin film electroluminescent device wherein an insulating layer (Y.sub.2 O.sub.3) is disposed between a pair of outer active layers of doped semiconductor (ZnS:Mn). Contiguous to one outer layer of ZnS:Mn is a metal electrode while a transparent electrode is contiguous to the other outer ZnS:Mn layer. The composite structure, moreover, is formed on and supported by a glass substrate. Electroluminescent phenomenon occurs primarily at the layer interfaces upon the application of an alternating voltage applied across electrodes. Such a structure is more resistant to failure due to the fact that the ZnS:Mn layers next to the electrodes act as current limiting layers for preventing breakdown and destruction of the metal electrode for a certain applied voltage which would otherwise occur in electroluminescent structures having the active ZnS:Mn layer sandwiched between two insulating layers.

Abstract: An orthogonal code division multiple access communications system is disclosed involving multiple users while providing orthogonal operation, meaning that there is substantially zero interference between users. All of the users employ a mutually different time permutation of the same multi-bit direct sequence pseudo noise code with a synchronous time reference for all of the users being established through a central node or station which communicates with all of the users preferably through a loopback synchronous timing scheme. Each pseudo noise code is followed by an extra processing bit that balances the number of one and zero bits in the composite information bit which has the effect of providing a code structure which will have a cross-correlation value of zero with the other time permutated codes which enables the system to operate as an orthogonal system.

Abstract: A dielectric waveguide ferrite resonance isolator capable of operating in the millimeter frequency range in a dielectric waveguide transmission line is provided. The isolator comprises a thin sheet of hexagonal ferrite material that has been affixed to a side of the dielectric waveguide and then placed between the pole pieces of an electromagnet in order to magnetize and fully orient the ferrite material.

Abstract: An electronic detection system for detecting intrusion thru a perimeter eoys a transmission line as a sensing element. In one embodiment, RF energy is transmitted: in another, pulses of DC. In either case, pseudo-random coding of the signals is employed. A preferred emboidiment of the invention utilizes a transmission line consisting of a twisted pair of wires enclosed in a non-deformable insulation and configured for shallow burial to effect concealment. Another shape is disclosed for laying-out over hard ground. A low ohmic ground is included under the line to improve performance. An intruder in the field of the line causes an RF reflection back towards the source, which reflection may be detected by Doppler range-gating techniques.

Abstract: A multipath interference reduction system for mobile subscriber access systems, each occupying one of a plurality of time slot channels. Interference caused by multipath returns is eliminated in the receiver portion of digital signal communications apparatus by a plurality of cascaded signal subtraction units wherein the detected signal is successively delayed by increasing multiples of the pulsewidth of the main lobe, varied in amplitude and subtracted from itself until all the multipath amplitudes of significance are subtracted out of the composite received signal.

Abstract: The apparatus comprises a geophone connected to a circuitry case containing battery, a voltage regulator, a solid state preamplifier and amplifier tuned to respond to seismic signals between 2 and 25 Hz. The amplified seismic signals are rectified and applied to a microammeter connected to efficiently respond to pulsations at the step frequency of walking or crawling personnel. The apparatus can be used to measure seismic noise and to determine soil conditions prior to the emplacement of an intrusion detection system.

Abstract: Expanded multiplexed noise codes formed from code mate pairs of equal code length and having autocorrelation functions which upon detection provides an impulse autocorrelation function are generated by delaying one of the code mate pairs (code b) by a time delay less than its code length and adding it to the other code mate pair (code a) to form a first expanded code mate (code A) while a second expanded code mate (code B) is generated by forming the complement of the delayed code b and adding it to code a. Such partial overlapping results in expanded codes which also compress to an impulse when detected with a matched filter. These expanded codes, moreover, are utilized in multiplexed noise code modulated communications systems.

Abstract: An arrangement is disclosed for piezoelectric resonators utilizing linear and parallel sides or flats located on the periphery and opposite ends of the resonator. These sides are located normal to the axes wherein collinear forces applied to the resonator produce a desired effect upon its natural resonant frequency. For mechanical sensor applications this effect is maximized while for applications requiring a stable frequency or time base this effect is minimized. The outline peripheral shape of the resonators utilizing this mounting arrangement varies in accordance with the crystallographic orientation present in each resonator.

Abstract: An FET oscillator includes means for controlling the gain of the oscillator to control its output level to thereby avoid limiting, and thus to reduce distortion of the oscillator output. A feedback loop is serially connected between the drain and gate electrodes to cause the gate direct voltage to increase negatively as drain output amplitude increases and thus reduce drain current and stabilize oscillator gain. The level of oscillation is adjustable by a potentiometer connection to the gate.

Abstract: An active method and apparatus for suppressing or cancelling the effects of vibration on quartz crystal controlled oscillators by generating an electrical signal which is a replica of the vibration acting on the crystal resonator, which signal is thereafter properly phased and applied directly to the crystal electrodes which thereby operates to substantially eliminate unwanted vibration-induced sidebands in the signal output of the oscillator.

Abstract: A signal processor circuit including a plurality of similar cascaded stages, each of which is capable of locking onto and tracking a different frequency of a multiple-frequency composite signal applied to the processor. Each of the stages may comprise a frequency locked loop plus a variable frequency stop, wherein the tuning of the variable frequency stop tracks the output of the frequency locked loop. The variable frequency stop circuit passes the non-locked components to the next similar stage which locks onto one of the remaining components.

Abstract: The acceleration sensitivity of an AT-cut quartz crystal plate resonator is educed by replacing the quartz crystal plate of the resonator with a quartz crystal plate having a flatter plate contour.

Abstract: A method is disclosed of operating a cold-cathode-cold-reservoir thyratron for laser/radar and other systems employing high voltage and current pulses using ZrVFe as the hydrogen thyratron material. According to the method, a hydride of ZrVFe is first formed and the hydrided material then placed in the cathode structure of the thyratron. The tube is then pumped down to its operating pressure of approximately 10.sup.-3 atmospheres, the hydrided material then acting as a ballast to maintain that partial pressure of hydrogen at room temperature.