DESIGN TECHNIQUES FOR LOW-POWER TELEMETRY
Design for low power lunar telemetry communications system
COMMUNICATION↗
SEARCH · Search NASA
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.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
A Low-power High-efficiency Dc to Dc Converter
Low power high efficiency dc to dc converter- regulator for electronic systems
ELECTRONIC EQUIPMENT↗
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.↗
Experimental performance of a low-power MPD arc thrustor
Low power magnetoplasmadynamic arc thrustor performance
PROPULSION SYSTEM PERFORMANCE↗
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.↗
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↗
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.↗
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.↗
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.↗
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.↗
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.↗
Evaluation of high-voltage, high-power, solid-state remote power controllers for amps
The Electrical Power Branch at Marshall Space Flight Center has a Power System Development Facility where various power circuit breadboards are tested and evaluated. This project relates to the evaluation of a particular remote power controller (RPC) energizing high power loads. The Facility equipment permits the thorough testing and evaluation of high-voltage, high-power solid-state remote power controllers. The purpose is to evaluate a Type E, 30 Ampere, 200 V dc remote power controller. Three phases of the RPC evaluation are presented. The RPC is evaluated within a low-voltage, low-power circuit to check its operational capability. The RPC is then evaluated while performing switch/circuit breaker functions within a 200 V dc, 30 Ampere power circuit. The final effort of the project relates to the recommended procedures for installing these RPC's into the existing Autonomously Managed Power System (AMPS) breadboard/test facility at MSFC.
Callis, Charles P.↗
The Design and Use of a Temperature-Compensated Hot-Film Anemometer System for Boundary-Layer Flow Transition Detection on Supersonic Aircraft
An airborne temperature-compensated hot-film anemometer system has been designed, fabricated, and used to obtain in-flight airfoil boundary-layer flow transition data by the NASA Ames-Dryden Flight Research Facility. Salient features of the anemometer include near constant sensitivity over the full flight envelope, installation without coaxial wiring, low-noise outputs, and self-contained signal conditioning with dynamic and steady-state outputs. The small size, low-power dissipation, and modular design make the anemometer suitable for use in modern high-performance research aircraft. Design of the temperature-compensated hot-film anemometer and its use for flow transition detection on a laminar flow flight research project are described. Also presented are data gathered in flight which is representative of the temperature-compensated hot-film anemometer operation at subsonic, transonic, and supersonic flight conditions.
Chiles, Harry R.↗
Systems analysis of a low-acceleration research facility
The Low-Acceleration Research Facility (LARF), an unmanned free-flier that is boosted from low-earth orbit to a desired altitude using an orbital transfer vehicle is discussed. Design techniques used to minimize acceleration-causing disturbances and to create an ultra-quiet workshop are discussed, focusing on residual acceleration induced by the environment, the spacecraft and experiments. The selection and integration of critical subsystems, such as electrical power and thermal control, that enable the LARf to accomodate sub-microgravity levels for extended periods of time are presented, including a discussion of the Low-Acceleration Module, which will supply the payload with 25.0 kW of power, and up to 11.8 kW in the low-power mode. Also, the data management, communications, guidance, navigation and control, and structural features of supporting subsystems are examined.
Martin, Gary L.↗
VLSI Universal Noiseless Coder
Proposed universal noiseless coder (UNC) compresses stream of data signals for efficient transmission in channel of limited bandwidth. Noiseless in sense original data completely recoverable from output code. System built as very-large-scale integrated (VLSI) circuit, compressing data in real time at input rates as high as 24 Mb/s, and possibly faster, depending on specific design. Approach yields small, lightweight system operating reliably and consuming little power. Constructed as single, compact, low-power VLSI circuit chip. Design of VLSI circuit chip made specific to code algorithms. Entire UNC fabricated in single chip, worst-case power dissipation less than 1 W.
Rice, Robert F.↗
A look at the Soviet space nuclear power program
The Soviet Union has been flying nuclear power sources in space since about 1965. For the most part these nuclear power sources have been low-power nuclear reactors using a thermoelectric conversion principle. Recently the Soviet Union has flown two satellites using a higher power reactor that employs a thermionic conversion system. Reentry of two of the earlier reactors on board Cosmos 954 and Cosmos 1402 plus the recent potential accident involving Cosmos 1900 have focused world attention on Soviet usage of space nuclear power. Despite these problems the evidence points toward a continued Soviet usage of nuclear power sources in space.
Inductors↗
Investigating Laser Beam Welding as an In-Space Joining Technique via Thermal Vacuum and Microgravity and Vacuum Experiments
In-space joining technologies are crucial for stimulating an in-space economy and for enabling sustained space exploration by in-space manufacturing and repair of metallic structures. Compared to brazing or soldering, in-space welding (ISW) can provide highly hermetic, strong, and complex joints, potentially without introducing additional material. However, the influence of extreme temperatures, reduced pressure, and reduced gravity on ISW is not yet fully elucidated. Several efforts at NASA are investigating laser beam welding (LBW) as a joining and repair method in both thermal vacuum (TVAC) and combined vacuum & reduced gravity environments. NASA Marshall Space Flight Center (MSFC) shepherded several ISW projects in its past, including the 1973 electron beam welding on Skylab, the 1989 low-power LBW on parabolic flights, and the unflown 1990s-era In-Space Welding Experiment. Recent parabolic flights and 3 degree-of-freedom ground testing build upon this heritage. A collaboration with the Ohio State University using NASA Langley Research Center (LaRC) hardware retrofitted for LBW achieved the first high-powered laser welds under vacuum and low gravity and developed a workforce capable developing such experimental hardware. A ground testing campaign at the MSFC Flat Floor simulated fit-up and welding representative of ISW in 3 degrees of freedom to emulate microgravity effects on inertial systems. One ongoing effort is a NASA Early Career Initiative project – Lunar Assembly and Servicing by Autonomous Robotics (LASAR). Ruggedized LBW components were developed by an external partner for use in TVAC. A TVAC-rated robotic arm was procured by MSFC and used in the first known robotic laser weld where all components save the laser generator were under vacuum. NASA Johnson Space Center (JSC) is advancing supervised autonomy of ISW. NASA LaRC continues to adapt their unique snowflake joint geometry, suitable for connecting segments in trusses and other structures, to LBW. Upcoming TVAC campaigns will focus on testing extreme temperatures, proving out autonomous operations, and demonstrating weld repair. Weld inspection will occur via a non-contact nondestructive evaluation (NDE) technique – electromagnetic acoustic transduction (EMAT). Another ongoing effort based at MSFC is the DISCMAN -- DIsk-Shaped Configurable and Modular vAcuum uNit – which seeks to development a compact, modular payload that can provide a vacuum environment while in a reduced gravity condition. This payload could support multiple in-space manufacturing developmental efforts, with the first demonstration technology being LBW. Currently, the design is targeting operations in the pressurized volume of a space station, but the payload could readily be adapted to other flight platforms such as parabolic or even suborbital vehicles. LASAR elucidates the effects of temperature and vacuum on LBW while DISCMAN probes those of vacuum and gravity. Through these complementary efforts, NASA is addressing the primary challenges of ISW across the space environment while simultaneously developing and maturing technologies including robotic systems and inspection methodologies for future practical implementation on the Moon and beyond. This approach is timely, as upcoming missions requiring sustained human presence in space will depend on reliable ISW capabilities to create robust metallic joints currently unproven in the space environment and to perform repairs in situ .
hypogravity↗
A Comparison of Battery Charge Controller Technologies for Wave Energy Converters: Preprint
Wave energy is a uniquely challenging field for electrical system designers. High peak and low average power potential with a constantly varying energy input is difficult to harness and control through conventional means. To power the blue economy, low-powered wave energy converters (WECs) need batteries for energy storage. Safely and effectively charging batteries from waves requires a charge controller to properly monitor and control voltage and current going to the battery. Currently, off-the-shelf charge controllers exist for other renewable generation such as wind, hydro, and solar. Two topologies were validated: a buck converter and a pulse width modulation (PWM) charge controller. Using an in-lab dry testbed, wave energy power inputs were simulated to properly validate the effectiveness of existing charge controller technologies, identifying the shortcomings and improvements needed to effectively harness wave energy.
battery storage↗