Abstract: A transmitter generates three signals for sequential transmission. These signals are an unmodulated r.f. carrier, an r.f. carrier amplitude modulated by a first audio frequency waveform and an r.f. carrier amplitude modulated by a second audio frequency waveform which is distinguishable from the first and which may be employed as a means for identifying a particular transmitter. The composite, sequentially transmitted signal may be varied in terms of the individual signal transmission sequence, the duration of the individual signals, overall composite signal repetition rate and the frequency of the second audio waveform. Various combinations of signal variations may be employed to transmit different information.

Abstract: A digitized synchronous demodulator is constructed entirely of digital components including timing logic, an accumulator, and means to digitally filter the digital output signal. Indirectly, it accepts, at its input, periodic analog signals which are converted to digital signals by traditional analog-to-digital conversion techniques. Broadly, the input digital signals are summed to one of two registers within an accumulator, based on the phase of the input signal and mediated by timing logic. At the end of a predetermined number of cycles of the inputted periodic signals, the contents of the register that accumulated samples from the negative half cycle is subtracted from the accumulated samples from the positive half cycle. The resulting difference is an accurate measurement of the narrow band amplitude of the periodic input signal during the measurement period.

Abstract: A cable-compliant robotic joint includes two "U" configuration cross-section brackets with their "U" cross-sections lying in different planes, one of the brackets being connected to a robot arm and the other to a tool. Additional angle brackets are displaced from the other brackets at corners of the robotic joint. All the brackets are connected by cable segments which lie in one or more planes which are perpendicular to the direction of tool travel as it approaches a work object. The compliance of the joint is determined by the cable segment characteristics, such as their length, material, angle, stranding, pre-twisting and pre-stressing.

Abstract: A compliant joint is provided for prosthetic and robotic devices which permits rotation in three different planes. The joint provides for the controlled use of cable under motion. Perpendicular outer mounting frames are joined by swaged cables that interlock at a center block. Ball bearings allow for the free rotation of the second mounting frame relative to the first mounting frame within a predetermined angular rotation that is controlled by two stop devices. The cables allow for compliance at the stops and the cables allow for compliance in six degrees of freedom enabling the duplication or simulation of the rotational movement and flexibility of a natural hip or knee joint, as well as the simulation of a joint designed for a specific robotic component for predetermined design parameters.

Abstract: Fluoroepoxy compounds are made by reacting a fluoroepoxy resin with an effective curing agent, such as an adduct amine, and, while the compound is sufficiently liquid to wet a fluoroplastic surface, it may be applied to a fluoroplastic adherend, such as a Teflon, to be employed as an adhesive, to form various fluoroplastic products, without requiring any surface treatment of the adherend. The compounds are intentionally formulated with high fluorine contents, normally above 46% by weight, preferably for bonding fluoroplastics with a high F-content, above 55% by weight.

Abstract: An active vibration damper system, for bending in two orthogonal directions and torsion, in each of three mutually perpendicular axes is located at the extremities of the flexible appendages of a space platform. The system components for each axis includes: an accelerometer, filtering and signal processing apparatus, and a DC motor-inertia wheel torquer. The motor torquer, when driven by a voltage proportional to the relative vibration tip velocity, produces a reaction torque for opposing and therefore damping a specific modal velocity of vibration. The relative tip velocity is obtained by integrating the difference between the signal output from the accelerometer located at the end of the appendage with the output of a usually carried accelerometer located on a relatively rigid body portion of the space platform. A selector switch, with sequential stepping logic or highest modal vibration energy logic, steps to another modal tip velocity channel and receives a signal voltage to damp another vibration mode.

Abstract: An encoded information transmitter which transmits a radio frequency carrier that is amplitude modulated by a constant frequency waveform and thereafter amplitude modulated by a predetermined encoded waveform, the constant frequency waveform modulated carrier constituting an acquisition signal and the encoded waveform modulated carrier constituting an information bearing signal, the acquisition signal providing enhanced signal acquisition and interference rejection favoring the information bearing signal. One specific application for this transmitter is as a distress transmitter where a conventional, legislated audio tone modulated signal is transmitted followed first by the acquisition signal and then the information bearing signal, the information bearing signal being encoded with, among other things, vehicle identification data.

Abstract: A wick for use in a capillary loop pump heat pipe. The wick material is an essentially uniformly porous, permeable, open-cell, silicon dioxide/aluminum oxide inorganic ceramic foam having a silica fiber to alumina fiber ratio, by weight, of about 78 to 22, respectively, a density of 6 lbs/ft.sup.3, and an average pore size of less than 5 microns. A representative material having these characteristics is Lockheed Missiles and Space Company, Inc. HTP 6-22. This material is fully compatible with the FREONs and anhydrous ammonia and allows for the use of these very efficient working fluids, and others, in capillary loops.

Abstract: A reflection oscillator is provided which employs an active device operated in its roll-off region and two resonant circuits. For an oscillator employing a bipolar transistor, the emitter is connected to a series resonant capacitor-crystal network and the base is connected to an L-C tank circuit with the transistor being operated in the roll-off region of its gain versus frequency curve. This will provide a very high frequency of operation with a relatively inexpensive, low frequency, active device. These oscillators are easily tuned, stable, and require little d.c. power.

Abstract: A simple and inexpensive crystal oscillator is provided which employs negative voltage gain, single pole response amplifiers. The amplifiers may include such configurations as gate inverters, operational amplifiers and conventional bipolar transistor amplifiers, all of which operate at a frequency which is on the roll-off portion of their gain versus frequency curve. Several amplifier feedback circuit variations are employed to set desired bias levels and to allow the oscillator to operate at the crystal's fundamental frequency or at an overtone of the fundamental frequency. The oscillator is made less expensive than comparable oscillators by employing relatively low frequency amplifiers and operating them at roll-off, at frequencies beyond which they are customarily used. Simplicity is provided because operation at roll-off eliminates components ordinarily required in similar circuits to provide sufficient phase-shift in the feedback circuitry for oscillation to occur.

Abstract: Electrodes of a high power, microwave field effect transistor are substantially matched to external input and output networks. The field effect transistor includes a metal ground plane layer, a dielectric layer on the ground plane layer, a gallium arsenide active region on the dielectric layer, and substantially coplanar spaced source, gate and drain electrodes having active segments covering the active region. The active segment of the gate electrode is located between edges of the active segments of the source and drain electrodes. The gate and drain electrodes include inactive pads remote from the active segments thereof. The pads are connected directly to the input and output networks. The source electrode is connected to the ground plane layer.

Abstract: Thermosetting fluoropolymer foams are made by mixing fluid form thermosetting fluoropolymer components having a substantial fluorine content, placing the mixture in a pressure tight chamber, filling the chamber with a gas, at relatively low pressure, that is unreactive with the fluoropolymer components, allowing the mixture to gel, removing the gelled fluoropolymer from the chamber and thereafter heating the fluoropolymer at a relatively low temperature to simultaneously cure and foam the fluoropolymer. The resulting fluoropolymer product is closed celled with the cells storing the gas employed for foaming. The fluoropolymer resins employed may be any thermosetting fluoropolymer including fluoroepoxies, fluoropolyurethanes and fluoroacrylates.

Abstract: A cryogenic cooler is provided for use in craft such as launch, orbital and space vehicles subject to substantial vibration, changes in orientation and weightlessness. The cooler contains a small pore, large free volume, low density material to restrain a cryogen through surface tension effects during launch and zero-g operations and maintains instrumentation within the temperature range of 10.degree.-140.degree. K. The cooler operation is completely passive, with no inherent vibration or power requirements.

Abstract: A receiver and transmitter are provided for a distress incident locating telecommunications system. The receiver is a superheterodyne AM receiver which applies the received distress transmissions to a normally unlocked phaselock loop which locks onto the unmodulated carrier signal portion of the distress transmission. The duration of the phaselock loop being locked, and unlocked immediately after being locked, are measured and compared to predetermined values to find a match. Each of the predetermined values corresponds to an item of information, and if a match is found, the receiver indicates it. The receiver is also capable of extracting audio information present in the distress transmission. The transmitter generates three signals which can be applied to a transmitting antenna. These signals are a radio frequency carrier signal, and a carrier signal modulated by a distress waveform or by an audio signal.

Abstract: An emergency locating transmitting (ELT) system comprising a legislated ELT modified with an interface unit and connected by a multiwire cable to a remote control monitor (RCM), typically located at the pilot position. The RCM can remotely (1) test the ELT by disabling the legislated swept tone and allowing transmission of a single tone, (2) turn the ELT "on" for legislated ELT transmission, and (3) reset the ELT to an "armed" condition. The RCM also provides visual and audio indications of transmitter operating condition as well as ELT battery condition. Removing the RCM or shorting or opening the interface input connections will not affect traditional ELT operation.

Abstract: A wick for use in a capillary loop pump heat pipe. The wick material is an essentially uniformly porous, permeable, open-cell, polyethylene thermoplastic foam having an ultra high average molecular weight of from approximately 1,000,000 to 5,000,000, and an average pore size of about 10 to 12 microns. A representative material having these characteristics is POREX UF which has an average molecular weight of about 3,000,000. This material is fully compatible with the FREONs and anhydrous ammonia and allows for the use of these very efficient working fluids in capillary loops.

Abstract: A three axis attitude control system for an orbiting body, such as a spacecraft, comprises a motor driven flywheel supported by a torque producing active magnetic bearing. Free rotation of the flywheel is provided about its central axis and together with limited angular torsional deflections of the flywheel about two orthogonal axes which are perpendicular to the central axis. The motor comprises an electronically commutated DC motor, while the magnetic bearing comprises a radially servoed permanent magnet biased magnetic bearing capable of producing cross-axis torques on the flywheel. Three body attitude sensors for pitch, yaw and roll generate respective command signals along three mutually orthogonal axes (x, y, z) which are coupled to circuit means for energizing a set of control coils for producing torques about two of the axes (x and y) and speed control of the flywheel about the third (z) axis.

Abstract: Thermosetting fluorodiepoxide polymer foams are made by mixing fluid form thermosetting fluorodiepoxide polymer components having a substantial fluorine content, placing the mixture in a pressure tight chamber, filling the chamber with a gas, at relatively low pressure, that is unreactive with the fluorodiepoxide polymer components, allowing the mixture to gel, removing the gelled fluorodiepoxide polymer from the chamber and thereafter heating the fluorodiepoxide polymer at a relatively low temperature to simultaneously cure and foam the fluorodiepoxide polymer. The resulting fluorodiepoxide polymer product is closed celled with the cells storing the gas employed for foaming.