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Proposed control subsystem adjusts power radiated by uplink transmitter in Earth station/satellite relay station/ Earth station communication system. Adjustments made to compensate for anticipated changes in attenuation by rain. Raw input is a received downlink beacon singal, amplitude of which affected not only by rain fade but also by scintillation, attenuation in atmospheric gases, and diurnal effects.
Farquhar described several libration point navigation concepts that would appear to support NASA s current exploration vision. One concept is a Lunar Relay Satellite operating in the vicinity of Earth-Moon L2, providing Earth-to-lunar far-side and long- range surface-to-surface navigation and communications capability. Reference [ 1] lists several advantages of such a system in comparison to a lunar orbiting relay satellite constellation. Among these are one or two vs. many satellites for coverage, simplified acquisition and tracking due to very low relative motion, much longer contact times, and simpler antenna pointing. An obvious additional advantage of such a system is that uninterrupted links to Earth avoid performing critical maneuvers "in the blind." Another concept described is the use of Earth-Moon L1 for lunar orbit rendezvous, rather than low lunar orbit as was done for Apollo. This rendezvous technique would avoid large plane change and high fuel cost associated with high latitude landing sites and long stay times. Earth-Moon L1 also offers unconstrained launch windows from the lunar surface. Farquhar claims this technique requires only slightly higher fuel cost than low lunar orbit rendezvous for short-stay equatorial landings. Farquhar also describes an Interplanetary Transportation System that would use libration points as terminals for an interplanetary shuttle. This approach would offer increased operational flexibility in terms of launch windows, rendezvous, aborts, etc. in comparison to elliptical orbit transfers. More recently, other works including Folta[3] and Howell[4] have shown that patching together unstable trajectories departing Earth-Moon libration points with stable trajectories approaching planetary libration points may also offer lower overall fuel costs than elliptical orbit transfers. Another concept Farquhar described was a Deep Space Relay at Earth-Moon IA and/or L5 that would serve as a high data rate optical navigation and communications relay satellite. The advantages in comparison to a geosynchronous relay are minimal Earth occultation, distance from large noise sources on Earth, easier pointing due to smaller relative velocity, and a large baseline for interferometry if both L4 and L5 are used.
This report presents a successful technical learning integration of student interns in the Advanced Protection Laboratory space, located in the Grid Research Integration and Deployment Center (GRID-C) at the Department of Energy’s (DOE’s) Oak Ridge National Laboratory (ORNL). The Advanced Protection Laboratory was created for the primary goal of supporting DOE’s research projects and technical staff at ORNL. As a secondary goal, the space was used for collaborating with ORNL’s intern programs, providing support to the lab’s mentors and student interns. In 2024, three student interns spent a summer in the Advanced Protection lab space and were involved in the DarkNet Distributed Ledger Technology (DLT) project. The students had a great opportunity to gain hands-on experience with communication and protective relay equipment focused on information technology, data analytics, and cybersecurity. Experiences in the lab space with real equipment and software integration offer education and professional development for students, which is especially important because of a need in the energy industry to recruit highly skilled power and communication engineers.
NASA is exploring options for its Next Generation Relay (NGR) architecture while the current Tracking Data Relay Satellite System (TDRSS) completes its mission. The plan is to start implementation of the NGR beginning around 2025. The new system of proposed relay satellites will greatly increase the data rates between low Earth orbiting (LEO) satellite missions and the NASA TDRSS relay satellites. This increase in data rates will allow an unprecedented increase in data throughput from the LEO satellite missions back to the principal investigators (PI). This can be accomplished at Ka-band frequencies with high order modulation or at optical frequencies using Differential Phase Shift Keying (DPSK). The first satellite in the next set of relay satellites will have to be backward compatible with current technology to support ongoing and planned missions. The new set of satellites will be launched over a 10-year period with design lifetimes of at least 15 years. To meet these requirements, we analyzed various architectures and designed both the communication payloads on the relay satellite and candidate payloads on the user spacecraft by utilizing optical heads already designed. From this analysis, a demonstration optical satellite named “the Next Generation Optical Relay Pathfinder” with Ka-band capabilities was proposed to be built and launched with the purpose of evaluating an integrated high-speed optical and Ka-band communication system. Given a cost limit for the demonstration satellite, various satellite configurations were developed by varying the number of optical communication payloads. The communication payload on the relay satellite consisted of three major sub-systems: 1) Optical communication payload, 2) Ka-band communication payload, 3) Digital processing and routing of signals. The size, mass (weight), and power (SWaP) of the communication payload and other sub-systems of the satellite were obtained. The NASA Glenn Research Center COMPASS team designed the Pathfinder satellite and performed a cost analysis for its build and launch. In this paper, we first describe the needs, drivers, and the associated challenges for the Next Generation Optical Relay Pathfinder to be capable of connecting multiple LEO and GEO satellites at high data rates. Second, we detail the concept of operations (ConOps) and the system architecture, including the satellite configurations considered, their attributes and limitations, and the size of the satellite needed for each configuration. Third, we provide a summary of the Next Generation Optical Relay Pathfinder satellite design trades and its key elements. Finally, we present the path needed for implementation and operations.
The earth and orbiter body reflections involving the Tracking Data Relay Satellite (TDRS)/orbiter communications link are evaluated. Recommendations address operational conditions in order to avoid critical multipath impacts, modulation preferences during acquisition, and preferred scan limit implementation.
Fully connected uplink and downlink fully connected relay network systems using pseudo-noise spreading and despreading sequences subjected to maximizing the signal-to-interference-plus-noise ratio. The relay network systems comprise one or more transmitting units, relays, and receiving units connected via a communication network. The transmitting units, relays, and receiving units each may include a computer for performing the methods and steps described herein and transceivers for transmitting and/or receiving signals. The computer encodes and/or decodes communication signals via optimum adaptive PN sequences found by employing Cholesky decompositions and singular value decompositions (SVD). The PN sequences employ channel state information (CSI) to more effectively and more securely computing the optimal sequences.
In this study is presented two power system applications with distributed ledger technology (DLT) and smart contracts (SC) that were assessed in a Cyber-Grid-Guard System (CGGS) advanced testbed, with protective relays, power meters, communication devices, DLT devices, synchronized time source, clock displays and real time simulator. This CGGS testbed was set in the Advanced Protection Lab, 252 lab space of the Grid Research Integration and Deployment Center (GRID- C), at Oak Ridge National Laboratory. In power grids, customer-owned distributed energy resources (DERs) are more frequent than in the past, and the numbers of points of interconnection (POI) with customer-owned DERs have increased. Disruptive operation from DERs presents a risk to grid operations, and protective relays located at the POI are used to isolate out-of-tolerance or poorly behaving of DERs. Ensuring the integrity of data from the relays at the POI, and DLT could enhance the security of the power grids. The first application is a SC to define and control the allowable total power factor (TPF) of the DER (wind farm) output, and the terms of the SC are implemented using DLT with a CGGS for a customer-owned DER. The TPF SC was implemented by the CGGS using DLT. The experimental model was performed with a real-time simulator using a CGGS and relay in-the-loop. The data collected from the CGGS were used to execute the TPF SC. The TPF limits were between +0.9 and +1.0, and the breakers’ operation in the POI was controlled by the relay using the SC. The events were collected from the real-time simulator, CGGS, and SEL 700GT relay to validate a successful application of the TPF SC using DLT. The second application is a SC to measure and control the allowable voltage service limits (VSL) by the CGGS using DLT. The tests were performed by using a real-time simulator, CGGS and relay in-the-loop. The data was collected from the CGGS that executed the SC. The main constraints were defined based on ANSI C84.1 service voltage limits, and the operation of the breakers in the POI. The events were collected from the CGGS, and SEL 700GT relay to assess a successful operation of the VSL SC using DLT.
The NASA Spaceflight Tracking and Data Network (STDN) in the 1980's will employ the Tracking and Data Relay Satellite System (TDRSS). The TDRSS includes a pair of geosynchronously orbiting communications satellites which will relay data from most NASA earth-orbiting spacecraft directly to a TDRSS ground station in the U.S. A description is given of the expected evolution of the STDN, the supporting NASCOM, and the integrated communications and data handling configurations that will be needed for NASA space missions in the 1980's.
The results of the performance analysis performed on the Shuttle/Tracking and Data Relay Satellite System (TDRSS) communications system are presented. The existing Shuttle/TDRSS link simulation program were modified and refined to model the post-radio frequency interference TDRS hardware and to evaluate the performance degradation due to RFI effects. The refined link models were then used to determine, evaluate and assess expected S-band and Ku-band link performance. Parameterization results are presented for the ground station carrier and timing recovery circuits
S band communications repeater using retrodirective phased array on synchronous altitude data relay satellite /DRS/ for intersatellite and ground links
This investigation was commissioned by the Office of Electricity of the Department of Energy in response to reviewing the NERC State of Reliability report. The study is an attempt to proactively address electric utility industry needs. “Monitoring, analyzing, and tracking trends in Protection System Misoperations are critical to improve BES reliability. Historically, Protection System Misoperations have exacerbated the severity of most cascading power outages.” The NERC misoperations data shows that unnecessary trips are by far the leading category of reported misoperations and that a majority of misoperations are those of line protection packages. A significant number of misoperations are tied to microprocessor relays. Approximately one quarter of reported misoperations are due to incorrect settings and another one quarter of misoperations are due to relay failures/malfunctions and communication failures.
For several years before the launch of the Telstar satellite, research effort was directed toward an experiment with an active satellite capable of relaying a broadband communication channel. The intention was to utilize and test a number of novel techniques which had become available, to explore those areas in which the current technology was lacking, and to demonstrate the feasibility of this means of communication. This paper describes some of this work, the background of facts and beliefs on the basis of which a number of important choices were made, and the general state of the radio art upon which the Telstar program was built.
Navigation satellites for information during movements of manned/unmanned terrestrial vehicles containing position determination, communications and weather relay service and scientific sensors
Satellite use for two way communication and tracking relays from ground to manned orbiting spacecraft
The accomplishments of space technology are briefly reviewed, giving attention to the revolution in communication produced by relay satellites, advances in meteorology due to weather satellites, the exploration of the moon, and the Skylab Program. A new approach to space exploration will be provided by the Space Shuttle. Spacelab offers a wide variety of mission choices to the international scientific community. The study of plasma physics will provide information useful for the development of fusion reactors. The science of astronomy will be advanced by the High Energy Astronomy Observatory and a large space telescope.
The University of Michigan minipod, which is released from a balloon and floats down on a parachute, is designed for stratospheric testing. The present paper briefly describes the evolution of antenna designs for the minipod 1.5 GHz transceiver, which communicates with and relays information to an aircraft and ground station. The following stages are noted: ordinary monopole, crossed dipole, capacitative antenna, fat monopole, the addition of parasitic elements, and a thinner monopole with taper.
Foremost among the candidates for early utilization of the Shuttle-launched self-deployable structures are the space-based radio telescopes. Several space-based telescopes are examined including an orbiting VLBI terminal, an orbiting submillimeter telescope, and a large ambient deployable IR telescope. Particular consideration is given to the high-gain Orbiting Deep-Space Relay Station for communication with deep-space probes. Details of deployable antenna technology are discussed.
The paper considers data acquisition and projected applications of the Landsat-D observations. The Landsat-D system will use communication satellites to relay sensor measurements in near-real time to ground data processing facilities. Other improvements result from advanced capabilities of the Thematic Mapper (TM) over those of the Multispectral Scanner Subsystem which include: (1) better spatial resolution; (2) narrower spectral bands in the 0.5 to 0.9 micron region and new bands covering regions from 0.45 to 2.35 microns; and (3) better radiometric resolution. These improvements in spatial, spectral, and radiometric resolution are expected to enhance the satellite applicability in agriculture, forest and rangeland, water, and land use.