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At least 469 records · Page 26

New antenna feed revitalizes Space Shuttle tracker at NASA Edwards

An account is given of the upgrading of a 12-ft-diameter single-channel monopulse tracking system, which had been relegated to slaved backup status at NASA Edwards, to support research flights for Ames Dryden Research Center and for tracking orbital passes of the Space Shuttle and Shuttle landings both at Edwards and at White Sands. The improved system is now a stand-alone telemetry tracking system. A new conical scanning feed (known as Radscan) replaces the single channel monopulse feed in the upgraded system. Where previously the system would not autotrack at elevation angles below 5 degrees, it now automatically acquires the Space Shuttle when it appears on the horizon and autotracks from approximately 2 degrees in elevation to touchdown, and does so virtually unattended.

Wrin, J. W.↗

Microlock- a minimum weight radio instrumentation system for a satellite

The design, construction and laboratory testing of a satellite tracking system are described. The tracking mechanism employs a low power, lightweight flight transmitter in conjunction with a receiving system of advanced design. The flight transmitter will radiate 3 mw for three months and will provide two narrow hand telemetering channels in a unit having a total weight of 2 lb. The ground receiving equipment is capable of acquiring and tracking the beacon signal at a line-of-sight distance of 3000 miles and at any azimuth and elevation angle. Interferometer antennas could he used to determine the angular position of the satellite with an accuracy of one milliradian, which is equivalent to approximately ±0.04 sec in the determination of the period.

Earth Satellites↗

Orbit determination accuracies using satellite-to-satellite tracking

The results of the ATS-6/GEOS-3 and the ATS-6/NIMBUS-6 satellite-to-satellite tracking orbit determination experiments are reported. The tracking systems used in these experiments differ from the Tracking and Data Relay Satellite System (TDRSS), primarily in the use of one rather than two synchronous relay satellites. However, the simulations mentioned indicate that the insights gained from the experiments with regard to proper data reduction techniques and expected results are applicable to the TDRSS.

Vonbun, F. O.↗

An Evaluation of Recent Events Involving Hazardous Energy at INL Facilities

Idaho National Laboratory (INL) Facilities and Site Services (F&SS) has experienced 14 reportable events relating to work performed under lockout / tagout (LOTO) during the period of March 4, 2019 through August 18, 2020. The 14 events are described in Appendix A and were numerous enough and similar enough in nature to be indicative of an adverse trend that warranted further evaluation. A qualified cause analyst was assigned to lead a team in the review of these non-compliances, to determine commonalities, and to provide recommendations to the sponsoring organization. The team focused on both individual and institutional behaviors as well as the LOTO process and procedure. The non-compliances were reported in the Department of Energy (DOE) Occurrence Reporting and Processing System (ORPS) and/or the INL issues tracking system.

99 GENERAL AND MISCELLANEOUS↗

Doppler-cancelled response to VLF gravitational waves

The interaction of long periodic gravitational waves with a three link microwave system known as the Doppler Cancelling System is discussed. This system, which was developed for a gravitational redshift experiment, uses one-way and two-way Doppler informatin to construct the beat signal of two reference oscillators moving with respect to each other. The geometric optics approximation is used to derive the frequency shift produced on a light signal propagating in a gravitational wave space-time. The signature left on the Doppler-cancelled beat by burst and continuous gravitational waves is analyzed. A comparison is made between the response to gravitational waves of the Doppler Cancelling System and that of a Doppler tracking system which employs two-way, round-trip radio waves. A three-fold repetition of the gravitational wave form is found to be a common feature of the response functions of both systems. These two functions otherwise exhibit interesting differences.

Caporali, A.↗

IEA PVPS Task 13 Techno-Economic Study of Bifacial Photovoltaic Systems on Single Axis Trackers

The International Energy Agency PVPS Task 13 has assembled an international team of photovoltaic (PV) researchers from government labs, academia, and industry to study the specific application of bifacial PV modules deployed on tracking systems. This configuration is of particular interest as it has been identified as the PV system design with the lowest Levelized Cost of Electricity (LCOE) for over 90% of the world [1]. As such, much research, development, and commercial activity are focused on further optimizing this system design for different regions and markets, including field deployment and advanced modeling activities. Despite these efforts, many challenges remain to overcome with this system design. This conference paper will report on several areas the team is working on as part of this project. The first part of this study focuses on extensive interviews with PV tracker companies (we have identified 35) and customers worldwide to identify emerging technology trends, design diversity, market environments, and the reliability and performance of these systems. We will provide a market summary of technologies such as advanced tracking algorithms, methods for dealing with topography within the PV plant, different system configurations and layouts, backside irradiance optimization from albedo enhancement, and ground sculpting. We will also review dual-use applications of tracked bifacial systems, such as Agrivoltaics and Building-Integrated PV. These interviews are underway now, and we will be able to report our initial findings at the conference. The second part of the study focuses on summarizing performance monitoring and evaluation methods, with particular attention to capacity and acceptance testing for such systems. The third part of the study reviews performance modeling and yield assessment methods for these tracked bifacial PV systems. The final part of the study covers reliability and operations, and maintenance data from these systems.

albedo↗

Free-space laser communication technologies II; Proceedings of the Meeting, Los Angeles, CA, Jan. 15-17, 1990

Various papers on free-space laser communication technologies are presented. Individual topics addressed include: optical intersatellite link experiment between the earth station and ETS-VI, the Goddard optical communications program, technologies and techniques for lasercom terminal size, weight, and cost reduction, laser beam acquisition and tracking system for ETS-VI laser communication equipment, analog dividers for acquisition and tracking signal normalization, fine pointing mechanism using multilayered piezoelectric actuator for optical ISL system, analysis of SILEX tracking sensor performance, new telescope concept for space communication, telescope considered as a very high gain antenna, design of compact transceiver optical systems for optical intersatellite links, ultralightweight optics for laser communications, highly sensitive measurement method for stray light and retroreflected light, depolarization effects on free space laser transceiver communication systems, in-orbit measurements of microaccelerations of ESA's communication satellite Olympus, high-performance laser diode transmitter for optical free space communication, diode-pumped Nd:host laser transmitter for intersatellite optical communications, single-frequency diode-pumped laser for free-space communication.

Begley, David L.↗