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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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NASA NTRS1992

A 1-W, 30-ghz, CPW Amplifier for ACTS Small Terminal Uplink

The progress is described of the development of a 1 W, 30 GHz, coplanar waveguide (CPW) amplifier for the Advanced Communication Technology Satellite (ACTS)Small Terminal Uplink. The amplifier is based on Texas Instruments' monolithic microwave integrated circuit (MMIC) amplifiers; a three stage, low power amplifier, and a single stage, high power amplifier. The amplifiers have a power output of 190 mW and 0.710 W, gain of 23 and 4.2 dB, and efficiencies of 30.2 and 24 percent for the three stage and one stage amplifiers, respectively. The chips are to be combined via a CPW power divider/combiner circuit to yield the desired 1 W of output power.

Taub, Susan R.↗
NASA NTRS1992

A 1-W, 30-GHz, CPW amplifier for ACTS small terminal uplink

The progress to date of the development of a 1-W, 30-GHz, coplanar waveguide (CPW) amplifier for the Advanced Communication Technology Satellite (ACTS) Small Terminal Uplink is described. The amplifier is based on Texas Instruments' monolithic microwave integrated circuit (MMIC) amplifiers; a three-stage, low-power amplifier and a single stage, high-power amplifier. The amplifiers have a power output of 190 mW and 0.710 W, gain of 23 and 4.2 dB, and efficiencies of 30.2 and 24 percent for the three-stage and one-stage amplifiers, respectively. The chips are to be combined via a CPW power divider/combiner circuit to yield the desired 1 W of output power.

Taub, Susan R.↗
NASA NTRS1992

Planning for the semiconductor manufacturer of the future

Texas Instruments (TI) is currently contracted by the Air Force Wright Laboratory and the Defense Advanced Research Projects Agency (DARPA) to develop the next generation flexible semiconductor wafer fabrication system called Microelectronics Manufacturing Science & Technology (MMST). Several revolutionary concepts are being pioneered on MMST, including the following: new single-wafer rapid thermal processes, in-situ sensors, cluster equipment, and advanced Computer Integrated Manufacturing (CIM) software. The objective of the project is to develop a manufacturing system capable of achieving an order of magnitude improvement in almost all aspects of wafer fabrication. TI was awarded the contract in Oct., 1988, and will complete development with a fabrication facility demonstration in April, 1993. An important part of MMST is development of the CIM environment responsible for coordinating all parts of the system. The CIM architecture being developed is based on a distributed object oriented framework made of several cooperating subsystems. The software subsystems include the following: process control for dynamic control of factory processes; modular processing system for controlling the processing equipment; generic equipment model which provides an interface between processing equipment and the rest of the factory; specification system which maintains factory documents and product specifications; simulator for modelling the factory for analysis purposes; scheduler for scheduling work on the factory floor; and the planner for planning and monitoring of orders within the factory. This paper first outlines the division of responsibility between the planner, scheduler, and simulator subsystems. It then describes the approach to incremental planning and the way in which uncertainty is modelled within the plan representation. Finally, current status and initial results are described.

Fargher, Hugh E.↗
NASA NTRS1992

Scheduling revisited workstations in integrated-circuit fabrication

The cost of building new semiconductor wafer fabrication factories has grown rapidly, and a state-of-the-art fab may cost 250 million dollars or more. Obtaining an acceptable return on this investment requires high productivity from the fabrication facilities. This paper describes the Photo Dispatcher system which was developed to make machine-loading recommendations on a set of key fab machines. Dispatching policies that generally perform well in job shops (e.g., Shortest Remaining Processing Time) perform poorly for workstations such as photolithography which are visited several times by the same lot of silicon wafers. The Photo Dispatcher evaluates the history of workloads throughout the fab and identifies bottleneck areas. The scheduler then assigns priorities to lots depending on where they are headed after photolithography. These priorities are designed to avoid starving bottleneck workstations and to give preference to lots that are headed to areas where they can be processed with minimal waiting. Other factors considered by the scheduler to establish priorities are the nearness of a lot to the end of its process flow and the time that the lot has already been waiting in queue. Simulations that model the equipment and products in one of Texas Instrument's wafer fabs show the Photo Dispatcher can produce a 10 percent improvement in the time required to fabricate integrated circuits.

Kline, Paul J.↗
NASA NTRS1992

Deimos: A reddish, D-type asteroid spectrum

We have obtained high quality CCD spectra of Deimos from 0.5 to 1.0 microns at a spectral resolution of 15 A. The spectra are remarkably red, similar to the spectra of D type asteroids rather than those of carbonaceous chondrites or C type asteroids. During the 1988 opposition of Mars, we obtained new CCD spectra of its outer satellite, Deimos. The data were obtained over a 2 1/2 hour period on the night of 9 Oct., using the 1.54 meter Catalina telescope and the LPL long-slit CCD spectrometer. From 0.5 to 1.1 microns, the spectrum is dispersed across an 800 x 800 Texas Instruments CCD chip at a scale of 7.21 A per pixel for an effective lambda/delta(lambda) approximately equals 500. The primary observational difficulty in ground based spectroscopy of Deimos was its proximity to Mars. To minimize scattered light from Mars, Deimos was observed near greatest elongation. The spectrograph slit was narrowed to 2.5 arcseconds, slightly larger than the seeing disk. An apodizing mask at the re-imaged telescope primary, to remove the diffraction cross of Mars light caused by the telescope's secondary mirror mount. Residual scattered light was modeled and removed in data reduction. Solar analog stars BS560, BS2007, and BS8931 were observed to allow removal of telluric absorptions. The resulting spectrum is plotted with other data.

Grundy, William M.↗
NASA NTRS1993

Miniature Optical Wide-Angle-Lens Startracker (Mini-OWLS)

This paper provides a brief overview of the design considerations and the current status of the Miniature Optical Wide-Angle Lens Startracker Program. Mini-OWLS offers a revolutionary alternative to the conventional startracker. It is a small, lightweight, low cost, high performance startracker that can be used in a variety of applications including calibration and alignment of Inertial Measurement Units (IMU's) Mini-OWLS makes use of a strap down design incorporating Holographic Optical Elements (HOES) in place of conventional optics. HOES can be multiplexed so that the same aperture can be used for multiple separate optical paths looking in several directions simultaneously without startracker rotation. Additionally, separate Schmidt corrector plates are not required to compensate for spherical aberration. The optical assembly, or what would normally be considered as the telescope, is less than 20 cc in volume, weighs less than 55 grams, and contains the equivalent of three individual telescopes. Each one has a 4 deg Field of View (FOV) with a field of regard of 48 square degrees. Mini-OWLS has a bandwidth of approximately 300 nm in or near the visible wavelength. The projected resolution of the startracker is 5 to 10 arcseconds, depending on the centroiding algorithm used. The Mini-OWLS program was initiated last year and represents a miniaturized version of a similar design for aeronautical applications. The contract is managed by Wright Laboratory, Air Force Systems Command, Wright-Patterson AFB, Ohio, with funding from the Strategic Defense Initiative Organization through Eglin AFB. The initial phase of the program is to build and test a development unit. The second phase is to integrate the startracker with the Charles Stark Draper Laboratory Micromechanical Inertial Guidance System (MIGS) and the Signal Processing Packaging Design (SPPD) being developed by Texas Instruments. The preliminary design review was conducted in November 1991. Three-axes prototype telescope assemblies have been built and design evaluation tests initiated.

Miller, Rick↗
NASA NTRS1993

Design and construction of a prototype ACTS propagation terminal

The launch schedule for the Advanced Communication Technology Satellite (ACTS) spacecraft did not leave sufficient time for completion of the prototype ACTS Propagation Terminals (APT) prior to initiation of the APT production phase. In fact, the approach used was to construct and test all subassemblies of the terminal with special emphasis on the technically challenging portions. These include the RF front end that uses a state-of-the-art down converter which integrates a low noise amplifier, mixer, post amplifier, filter, and local oscillator port frequency doubler into a single small package. In addition, a new digital receiver that uses the latest DSP technology was developed. Both of these subassemblies were thoroughly tested. The highest risk technology in the APT program was the digital receiver. Several candidate algorithms and DSP chips were investigated early on, primarily under JPL sponsorship. A receiver was constructed based on Texas Instruments chip. The final prototype digital receiver was one based on an Analog Devices chip. The design and test results are documented in a report prepared for this grant. A Primary Design Review (PDR) was conducted 30 May 1991, and a Critical Design Review was held 7 Jul. 1992. Final complete documentation of the APT's will appear in the form of three reports: a hardware description report, a report on the data collection code (ACTS VIEW), and a report on the preprocessing code.

Stutzman, Warren↗
NASA NTRS1994

Software For A Laser Vibrometer

Vibration Pattern Imager (VPI) system and software designed to control and acquire data from laser vibrometer sensors. Based on personal computer, includes digital signal-processing (DSP) board and analog input/output (I/O) circuit board to control sensors and process data. Originally developed for use with Ometron VPI Sensor, adapted to any commercially available sensor that provides analog output signal and requires analog inputs for control of mirror position. VPI system includes graphical user interface providing for interactive control through keyboard and mouse-selected menu options. Main menu controls all functions for setup, acquisition of data, display, file operations, and leaving program. Two types of data acquired with system: single point or "full field". Written in C language and Texas Instrument' TMS320C30 assembly language.

Rizzi, Stephen A.↗
NASA NTRS1994

An Object-Oriented Graphical User Interface for a Reusable Rocket Engine Intelligent Control System

An intelligent control system for reusable rocket engines under development at NASA Lewis Research Center requires a graphical user interface to allow observation of the closed-loop system in operation. The simulation testbed consists of a real-time engine simulation computer, a controls computer, and several auxiliary computers for diagnostics and coordination. The system is set up so that the simulation computer could be replaced by the real engine and the change would be transparent to the control system. Because of the hard real-time requirement of the control computer, putting a graphical user interface on it was not an option. Thus, a separate computer used strictly for the graphical user interface was warranted. An object-oriented LISP-based graphical user interface has been developed on a Texas Instruments Explorer 2+ to indicate the condition of the engine to the observer through plots, animation, interactive graphics, and text.

Litt, Jonathan S.↗
NASA NTRS1992

Quest for excellence 5

The highlights of the 1992 Malcolm Baldrige National Quality Award winners - AT and T Network Systems Group, Transmission Systems Business Unit; Texas Instrument Defense Systems and Electronics Group; AT and T Universal Card Services; The Ritz Hotel CO; and The Granite Rock Company are presented, along with brief information about the company and their beliefs and business and production strategies for quality manufacturing and products.

Source record↗
NASA NTRS1990

A CLIPS expert system for maximizing alfalfa (Medicago Sativa L.) production

An alfalfa management expert system originally developed by Purdue University agricultural scientists on the PC Plus expert system shell from Texas Instrument has been updated and successfully converted to CLIPS (C Language Integrated Production System). This reduces the cost and legal restrictions associated with making the expert system available to agribusiness industries, extension personnel and farm managers and operators. The expert system includes recommendations concerning soil drainage, liming, P and K fertilization, weed control, variety selection and seeding rate including pure live seeds.

Engel, B. A.↗
NASA NTRS1995

Ka-band MMIC array system for ACTS aeronautical terminal experiment (Aero-X)

During the summer of 1994, the Advanced Communication Technology Satellite (ACTS) Aeronautical Terminal Experiment (Aero-X) was successfully completed by the NASA Lewis Research Center (LeRC) and the Jet Propulsion Laboratory (JPL). 4.8 and 9.6 Kbps duplex voice links were established between the LeRC Learjet and the ACTS Link Evaluation Terminal (LET) in Cleveland, Ohio, via the ACTS. The antenna system used in this demonstration was developed by LeRC and featured LeRC and US Air Force experimental arrays using GaAs MMIC devices at each radiating element for electronic beam steering and distributed power amplification. The antenna system consisted of three arrays mounted inside the LeRC Learjet, pointing out through the windows. An open loop tracking controller developed by LeRC used information from the aircraft position and attitude sensors to automatically steer the arrays toward ACTS during flight JPL ACTS Mobile Terminal (AMT) system hardware was used as transceivers both on the aircraft and at the LET. The single 32 element MMIC transmit array developed by NASA/LeRC and Texas Instruments has an EIRP of 23.4 dBW at boresight. The two 20 GHz MMIC receive arrays were developed in a cooperative effort with the USAF Rome Laboratory/Electronic System Center, taking advantage of existing USAF array development contracts with Boeing and Martin Marietta. The Boeing array has 23 elements and a G/T of 16/6 db/degK at boresight. The Martin Marietta array has 16 elements and a G/T of 16.1 db/degK at boresight. The three proof-of-concept arrays, the array control system and their integration and operation in the Learjet for Aero-X are described.

Raquet, Charles A.↗
NASA NTRS1996

MMIC Phased Array Demonstrations with ACTS

Over a one year period from May 1994 to May 1995, a number of demonstrations were conducted by the NASA Lewis Research Center (LeRC) in which voice, data, and/or video links were established via NASA's advanced communications technology satellite (ACTS) between the ACTS link evaluation terminal (LET) in Cleveland, OH, and aeronautical and mobile or fixed Earth terminals having monolithic microwave integrated circuit (MMIC) phased array antenna systems. This paper describes four of these. In one, a duplex voice link between an aeronautical terminal on the LeRC Learjet and the ACTS was achieved. Two others demonstrated duplex voice (and in one case video as well) links between the ACTS and an Army vehicle. The fourth demonstrated a high data rate downlink from ACTS to a fixed terminal. Array antenna systems used in these demonstrations were developed by LeRC and featured LeRC and Air Force experimental arrays using gallium arsenide MMIC devices at each radiating element for electronic beam steering and distributed power amplification. The single 30 GHz transmit array was developed by NASA/LeRC and Texas Instruments. The three 20 GHz receive arrays were developed in a cooperative effort with the Air Force Rome Laboratory, taking advantage of existing Air Force array development contracts with Boeing and Lockheed Martin. The paper describes the four proof-of-concept arrays and the array control system. The system configured for each of the demonstrations is described, and results are discussed.

Raquet, Charles A.↗
NASA NTRS1995

Silicon Micromachining in RF and Photonic Applications

Texas Instruments (TI) has developed membrane and micromirror devices since the late 1970s. An eggcrate space membrane was used as the spatial light modulator in the early years. Discrete micromirrors supported by cantilever beams created a new era for micromirror devices. Torsional micromirror and flexure-beam micromirror devices were promising for mass production because of their stable supports. TI's digital torsional micromirror device is an amplitude modulator (known as the digital micromirror device (DMD) and is in production development, discussed elsewhere. We also use a torsional device for a 4 x 4 fiber-optic crossbar switch in a 2 cm x 2 cm package. The flexure-beam micromirror device is an analog phase modulator and is considered more efficient than amplitude modulators for use in optical processing systems. TI also developed millimeter-sized membranes for integrated optical switches for telecommunication and network applications. Using a member in radio frequency (RF) switch applications is a rapidly growing area because of the micromechanical device performance in microsecond-switching characteristics. Our preliminary membrane RF switch test structure results indicate promising speed and RF switching performance. TI collaborated with MIT for modeling of metal-based micromachining.

Lin, Tsen-Hwang↗
NASA NTRS1995

The Fundamentals of Using the Digital Micromirror Device (DMD(TM)) for Projection Display

Developed by Texas Instruments (TI) the digital micromirror device (DMD(tm)) is a quickly emerging and highly useful micro-electro-mechanical structures (MEMS) device. Using standard semiconductor fabrication technology, the DMD's simplicity in concept and design will provide advantageous solutions for many different applications. At the rudimentary level, the DMD is a precision, semiconductor light switch. In the initial commercial development of DMD technology, TI has concentrated on projection display and hardcopy. This paper will focus on how the DMD is used for projection display. Other application areas are being explored and evaluated to find appropriate and beneficial uses for the DMD.

Yoder, Lars A.↗
NASA NTRS1998

Radial Velocity Detection of Extra-Solar Planetary Systems

The McDonald Observatory Planetary Search (MOPS) was designed to search for Jovian-mass planets in orbit around solar-type stars by making high-precision measurements of the Radial Velocity (RV) of a star, to attempt to detect the reflex orbital motion of the star around the star-planet barycenter. In our solar system, the velocity of the Sun around the Sun-Jupiter barycenter averages 12.3 m/ s. The MOPS survey started operation in September 1987, and searches 36 bright, nearby, solar-type dwarfs to 10 m/s precision. The survey was started using telluric O2 absorption lines as the velocity reference metric. Observations use the McDonald Observatory 2.7-m Harlan Smith Telescope coude spectrograph with the six-foot camera. This spectrograph configuration isolates a single order of the echelle grating on a Texas Instruments 800 x 800 CCD. The telluric line method gave us a routine radial velocity precision of about 15 m/s for stars down to about 5-th magnitude. However, the data obtained with this technique suffered from some source of long-term systematic errors, which was probably the intrinsic velocity variability of the terrestrial atmosphere, i.e. winds. In order to eliminate this systematic error and to improve our overall measurement precision, we installed a stabilized I2 gas absorption cell as the velocity metric for the MOPS in October 1990. In use at the telescope, the cell is placed directly in front of the spectrograph entrance slit, with starlight passing through the cell. The use of this sealed stabilized I2 cell removes potential problems with possible long-term drifts in the velocity metric. The survey now includes a sample of 36 nearby F, G, and K type stars of luminosity class V or IV-V.

Cochran, William D.↗
NASA NTRS1998

Interior Noise Reduction by Adaptive Feedback Vibration Control

The objective of this project is to investigate the possible use of adaptive digital filtering techniques in simultaneous, multiple-mode identification of the modal parameters of a vibrating structure in real-time. It is intended that the results obtained from this project will be used for state estimation needed in adaptive structural acoustics control. The work done in this project is basically an extension of the work on real-time single mode identification, which was performed successfully using a digital signal processor (DSP) at NASA, Langley. Initially, in this investigation the single mode identification work was duplicated on a different processor, namely the Texas Instruments TMS32OC40 DSP. The system identification results for the single mode case were very good. Then an algorithm for simultaneous two mode identification was developed and tested using analytical simulation. When it successfully performed the expected tasks, it was implemented in real-time on the DSP system to identify the first two modes of vibration of a cantilever aluminum beam. The results of the simultaneous two mode case were good but some problems were identified related to frequency warping and spurious mode identification. The frequency warping problem was found to be due to the bilinear transformation used in the algorithm to convert the system transfer function from the continuous-time domain to the discrete-time domain. An alternative approach was developed to rectify the problem. The spurious mode identification problem was found to be associated with high sampling rates. Noise in the signal is suspected to be the cause of this problem but further investigation will be needed to clarify the cause. For simultaneous identification of more than two modes, it was found that theoretically an adaptive digital filter can be designed to identify the required number of modes, but the algebra became very complex which made it impossible to implement in the DSP system used in this study. The on-line identification algorithm developed in this research will be useful in constructing a state estimator for feedback vibration control.

Lim, Tae W.↗
NASA NTRS2001

Compilation Techniques for Core Plus FPGA Systems

The overall system architecture targeted in this study is a core-plus-fpga design, which is composed of a core VLIW DSP with on-chip memory and a set of special-purpose functional units implemented using FPGAs. A figure is given which shows the overall organization of the core-plus-fpga system. It is important to note that this architecture is relatively simple in concept and can be built from off-the-shelf commercial components, such as one of the Texas Instruments 320C6x family of DSPs for the core processor.

Conte, Tom↗