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Results for “low-power systems”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Low-Power Baseline Test Results for the GPU 3 Stirling Engine

A 7.5 kW (10 hp) Stirling engine was converted to a research configuration in order to obtain data for validating Stirling-cycle computer simulations. Test results for a range of heater-tube gas temperatures, mean compression-space pressures, and engine speeds with both helium and hydrogen as the working fluid are summarized. An instrumentation system to determine indicated work is described and preliminary results are presented.

Thieme, L. G.↗
NASA NTRS1981

In-flight jet engine noise measurement system

An instrumentation system in flight tests for noise research is described which utilizes miniature transducers to measure low-amplitude, high-frequency fluctuating pressures in a jet engine mounted under the wing of a turboprop aircraft. The system employs a rotor-mounted FM telemeter to acquire data from eight fan-blade-mounted transducers which are subjected to up to 75,000 g's of loading. Data is transmitted from the rotor to an antenna mounted in the inlet-duct wall using a low-power, close-coupled RF link. The blade pressures and other inlet and stator-vane fluctuating pressures are recorded on airborne, magnetic-tape recorders. The flight instrumentation described also includes PCM techniques to encode and record a variety of quasi-static measurements to provide engine and aircraft performance data. The instrumentation and experimental measurements are of value to an improved understanding of noise sources in jet engines and for the advancement of jet-engine ground noise testing techniques.

Knight, V. H., Jr.↗
NASA NTRS1975

The Pioneer 10/11 and Helios A/B cosmic ray instruments

This paper describes the design and performance of a set of cosmic-ray particle experiments for the Pioneer 10/11 and Helios A/B space missions. These experiments had to be very light-weight, low-power and electronically sophisticated in order to meet the spacecraft and scientific requirements. Both sets of missions use several solid-state detector telescopes to measure protons from 100 KeV to 800 MeV and heavier ions up to Neon at 200 MeV per nucleon. Good performance is required for 7-8 years, and the system must tolerate large vibration loads and ionizing radiation doses up to 500,000 rads.

Stilwell, D. E.↗
NASA NTRS1973

A New GaAs Laser Radar for Atmospheric Measurements

A special GaAs lidar using fiber coupled diode lasers was constructed for the purpose of measuring the extinction coefficient distribution within a large atmospheric volume at a rate compatible with atmospheric kinematics. The technique is based on taking backscatter signature ratios over spatial increments after the returns are normalized by pulse integration. Essential aspects of the lidar design are beam pulse power, repetition rate, detection system dynamic range and decay linearity. It was necessary to preclude the possibility of eye hazard under any operating conditions, including directly viewing the emitting aperture at close distance with a night-adapted eye. The electronic signal processing and control circuits were built to allow versatile operations. Extinction coefficient measurements were made in fog and clouds using a low-power laboratory version of the lidar, demonstrating feasibility. Data are presented showing range squared corrected backscatter profiles converted to extinction coefficient profiles, temporal signal fluctuations, and solar induced background noise. These results aided in the design of the lidar which is described. Functional tests of this lidar and the implications relevant to the design of a prototype model are discussed. This work was jointly sponsored by Sperry Rand Corporation under its Independent Research and Development program; the Air Force Avionics Laboratory, Wright Field, Dayton, Ohio; and the Naval Ammunition Depot, Crane, Indiana.

Brown, R. T.↗
NASA NTRS1982

Baseband processor development for the Advanced Communications Satellite Program

An onboard-baseband-processor concept for a satellite-switched time-division-multiple-access (SS-TDMA) communication system was developed for NASA Lewis Research Center. The baseband processor routes and controls traffic on an individual message basis while providing significant advantages in improved link margins and system flexibility. Key technology developments required to prove the flight readiness of the baseband-processor design are being verified in a baseband-processor proof-of-concept model. These technology developments include serial MSK modems, Clos-type baseband routing switch, a single-chip CMOS maximum-likelihood convolutional decoder, and custom LSL implementation of high-speed, low-power ECL building blocks.

Moat, D.↗
NASA NTRS1978

Miniature interferometer terminals for earth surveying

A system of miniature radio interferometer terminals was proposed for the measurement of vector baselines with uncertainties ranging from the millimeter to the centimeter level for baseline lengths ranging, respectively, from a few to a few hundred kilometers. Each terminal would have no moving parts, could be packaged in a volume of less than 0.1 cu m, and would operate unattended. These units would receive radio signals from low-power (10 w) transmitters on earth-orbiting satellites. The baselines between units could be determined virtually instantaneously and monitored continuously as long as at least four satellites were visible simultaneously.

Counselman, C. C., III↗
NASA NTRS1968

Adaptive control circuit prevents amplifier saturation

Adaptive control circuit prevents saturation of push-pull output amplifiers used in low-power, low-torque suspension system. The adaptive control circuit senses how near the output amplifiers are to saturation and sets the B voltage in such a way as to keep them just clear of saturation.

Nondsieck, A. J.↗
NASA NTRS1972

A narrowband, crystal controlled biomedical telemetry system.

A miniature, single-channel, crystal-controlled transmitter has been developed for biomedical applications. A narrow-band frequency modulation (plus or minus 7 kHz) of the RF is used to achieve maximum operating range with minimum transmitting power. The radiated power is limited to stay within the 50 microvolts/m at 15 m FCC requirement for low-power transmitters in the 88- to 108-MHz band. This technique offers a number of advantages. First only manufacturer's type approval is required for the device and the user does not need a license. Second maximum operating range can be achieved within the FCC power limitations by using a narrow-band that is consistent with the required medical information bandwidth. A third advantage in using the 88- to 108-MHz band is that the commercial FM stations are relatively widely spaced and carefully regulated so that by selecting the transmitter's frequency in the guard band between stations, minimum interference from other transmitter sources is encountered.

Westbrook, R. M.↗
NASA NTRS1975

Space vehicle Viterbi decoder

The design and fabrication of an extremely low-power, constraint-length 7, rate 1/3 Viterbi decoder brassboard capable of operating at information rates of up to 100 kb/s is presented. The brassboard is partitioned to facilitate a later transition to an LSI version requiring even less power. The effect of soft-decision thresholds, path memory lengths, and output selection algorithms on the bit error rate is evaluated. A branch synchronization algorithm is compared with a more conventional approach. The implementation of the decoder and its test set (including all-digital noise source) are described along with the results of various system tests and evaluations. Results and recommendations are presented.

Source record↗
NASA NTRS1977

Very low-power power supplies

Unit may be used in systems requiring milliwatt power for bias voltage functions and can be used as control mechanism for large electric power systems. Logic and energy storage techniques yield processing efficiencies of 1000 to 1 over conventional designs.

Roy, N. L.↗
NASA NTRS1977

Low-power anemometer

Device allows wind speeds to be measured with less power by alternating hot-wire or hot-film heating periods with measurement periods. System includes reference auxiliary circuits to generate V sub ref and ramp voltage (E sub 3) and reference half of bridge circuit. Circuit permits use of several sensing films with common temperature compensation sensor.

Gilje, R. I.↗
NASA NTRS1978

Design considerations for solar power satellites

This report summarizes the performance characteristics of a conceptual solar power satellite (SPS) system with emphasis on the microwave power transmission system. The latest tradeoff studies on photovoltaic and thermal systems for converting solar energy into electricity at the satellite are reviewed. The microwave system, consisting of dc-RF amplifiers, a 1-km phased array, and a ground antenna/rectifier scheme is capable of delivering 5 GW of power to the commercial grid. The transmission efficiencies of smaller system sizes (down to 1 GW) are compared with that of the nominal 5 GW system. At present the frequency region of interest is the IMS (industrial, medical, and scientific) band at 2450 plus or minus 50 MHz. Economic and technical tradeoffs as a function of the microwave operating frequency are considered. Candidate dc-RF power converter tubes, including medium-power amplitrons, high-power klystrons, and low-power solid state amplifiers, are examined.

Arndt, G. D.↗
NASA NTRS1980

An adjustable solar concentrator

Fixed cylindrical converging lenses followed by movable parabolic mirror focus solar energy on conventional linear collector. System is low cost and accomodates daily and seasonal movements of the sun. Mirrors may be moved using simple, low-power electrical motors.

Collins, E. R., Jr.↗
NASA NTRS1983

An approach to optimization of low-power Stirling cryocoolers

A method for optimizing the design (shape of the displacer) of low power Stirling cryocoolers relative to the power required to operate the systems is described. A variational calculation which includes static conduction, shuttle and radiation losses, as well as regenerator inefficiency, was completed for coolers operating in the 300 K to 10 K range. While the calculations apply to tapered displacer machines, comparison of the results with stepped displacer cryocoolers indicates reasonable agreement.

Sullivan, D. B.↗