Tech Briefs

Miniature Housings for Electronics With Standard Interfaces

A family of general-purpose miniature housings has been designed to contain diverse sensors, actuators, and drive circuits plus associated digital electronic readout and control circuits. Each housing fits within an envelope having dimensions of about 2-1.4 by 1-3.4 by 1.2 in. (about 5.7 by 4.4 by 1.3 cm). Each housing can be secured to a mating carrier by use of screws or epoxy; this mounting scheme helps the housings and their contents to withstand severe vibrations and ensures thermal conduction for dissipation of heat generated during operation of the contained circuitry. The circuits contained in the housings communicate with the external world via standard RS-485 interfaces. Multiple units comprising housings and their contents can easily be electrically connected together in a daisychain arrangement, within which individual units are addressable via the RS-485 bus. Hence, a single master computer connected to the bus can program, or read data from, any or all such units. Examples of such units include small motor drives, programmable thermostats, data loggers, and programmable controllers. There are numerous potential uses for these units in medical equipment, automotive electronics, manufacturing equipment, and robots.

Posted in: Briefs, Electronics & Computers

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Receiver Would Control Phasing of a Phased-Array Antenna

Peaks and nulls would be aimed to optimize reception. In a proposed digital signal-processing technique, a radio receiver would control the phasing of a phased-array antenna to aim the peaks of the antenna radiation pattern toward desired signal sources while aiming the nulls of the pattern toward interfering signal sources. The technique was conceived for use in a Global Positioning System (GPS) receiver, for which the desired signal sources would be GPS satellites and typical interference sources would be terrestrial objects that cause multipath propagation. The technique could also be used to optimize reception in spread spectrum cellular-telephone and military communication systems.

Posted in: Briefs, TSP, Electronics & Computers

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Modern Design of Resonant Edge-Slot Array Antennas

Better antennas can be designed at lower cost. Resonant edge-slot (slotted-waveguide) array antennas can now be designed very accurately following a modern computational approach like that followed for some other microwave components. This modern approach makes it possible to design superior antennas at lower cost than was previously possible.

Posted in: Briefs, Electronics & Computers

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Simplified Optics and Controls for Laser Communications

A document discusses an architecture of a spaceborne laser communication system that provides for a simplified control subsystem that stabilizes the line of sight in a desired direction. 

Posted in: Briefs, TSP, Electronics & Computers

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Coherent Detection of High-Rate Optical PPM Signals

Quantum-limited performance is achievable. A method of coherent detection of highrate pulse-position modulation (PPM) on a received laser beam has been conceived as a means of reducing the deleterious effects of noise and atmospheric turbulence in free space optical communication using focal plane detector array technologies. In comparison with a receiver based on direct detection of the intensity modulation of a PPM signal, a receiver based on the present method of coherent detection performs well at much higher background levels.

Posted in: Briefs, TSP, Electronics & Computers

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Ultrasonically Actuated Tools for Abrading Rock Surfaces

These offer the same advantages as do ultrasonically actuated drilling and coring tools. An ultrasonic rock-abrasion tool (URAT) was developed using the same principle of ultrasonic/sonic actuation as that of the tools described in two prior NASA Tech Briefs articles: “Ultrasonic/Sonic Drill/Corers With Integrated Sensors (), Vol. 25, No. 1 (January 2001), page 38 and “Ultrasonic/Sonic Mechanisms for Drilling and Coring” (), Vol. 27, No. 9 (September 2003), page 65. Hence, like those tools, the URAT offers the same advantages of low power demand, mechanical simplicity, compactness, and ability to function with very small axial loading (very small contact force between tool and rock).

Posted in: Briefs, TSP, Mechanical Components, Mechanics

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Active Struts With Variable Spring Stiffness and Damping

These struts would act as linear actuators and controllable shock absorbers.Controllable active struts that would function as linear actuators with variable spring stiffness and damping have been proposed as components of advanced suspension systems of future wheeled ground vehicles. The contemplated advanced suspension systems would include computer-based control subsystems that would continually adjust the actuator responses to obtain optimal combinations of safety and comfort under operating conditions ranging from low speeds over smooth roads to high speeds over rough, unpaved ground. The proposed struts and suspension systems were originally intended for use in military vehicles, but there could also be a broad commercial market for them in trucks and sport utility vehicles.

Posted in: Briefs, TSP, Mechanical Components, Mechanics

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