Tactical Satellite Research Articles

Synchronization of Frequency Hopping by LSTM Network for Satellite Communication System

In this letter, a novel method for synchronization of frequency hopping signal is proposed for tactical satellite communication system. Proposed method consists of serial search for coarse acquisition and use of long short-term memory (LSTM) network for fine acquisition. During training, the LSTM network is able to learn trend of energy signal used for fine acquisition. As a result, it can perform quick and robust fine acquisition in the presence of noise. Validation of proposed method is conducted by simulations. Simulation results show that the proposed method leads to decreased time for synchronization and improved timing estimation performance, as compared to other methods.

The source and nature of general purpose technologies for supporting next K-waves: Global leadership and the case study of the U.S. Navy's Mobile User Objective System

A fundamental problem in the field of the technological studies is to explain the source and nature of general purpose technologies (GPTs) that can support the patterns of long waves and socio-economic progress of nations. The study here confronts this problem by applying the theoretical framework of global leadership-driven innovations, which endeavors to clarify and to generalize whenever possible, the source and nature of a new GPT in a not-too-distant future. This study suggests that one of contributing factors that may support the next GPT is due to strategic investments for the U.S. Navy's Mobile User Objective System (MUOS). This scientific and technological investment for U.S. military has the purpose to reinforce U.S. global leadership and, at the same time, can induce clusters of new technology in society. The MUOS is a constellation of ground-breaking satellites for next-generation narrowband tactical satellite communications system, which makes prior products obsolete (e.g., UHF Follow-On satellites). This technological system and related technological search for U.S. military are developing new information and communications technologies (ICTs) that are bringing the future of worldwide mobile satellite communications into reality. Overall, then, this study shows, by applying a new theory, some invariant factors of the source of GPTs and a possible new technological system for supporting long-run dynamics of current Kondratieff wave and future human development in society.

Parameter Requirements for Noncooperative Satellite Maneuver Reconstruction Using Adaptive Filters

The Responsive Orbits division of the Center for Space Research and Assurance in the Aeronautics and Astronautics Department of the Air Force Institute of Technology investigates short-term tactical satellite missions that require frequent maneuvers. Pairing research in designing and conducting avoidance maneuvers with research in detecting and tracking maneuvering satellites sets the stage for developing and improving both areas. Strategies in stochastic filtering, smoothing, multiple model adaptive estimation, and maneuver reconstruction are developed to track a high-priority satellite. The article develops a wide range of simulations that modify the maneuver type, tracking antenna performance, antenna coverage, reconstruction method, filtering approach, and number of postmaneuver passes collected. The results determine the levels of error covariance necessary to perform successful maneuver reconstructions. Additionally, the results provide maneuver reconstruction confidence percentages based on the estimated covariance and number of postmaneuver passes.

Thruster Attitude Control System Design and Performance for Tactical Satellite 4 Maneuvers

During the initial mission operation, the perigee altitude of the Tactical Satellite 4’s highly elliptical orbit was raised from 185 to 700 km through several delta- maneuvers. Tactical Satellite 4 employs two deployable solar arrays that have structural bending modes less than 1 Hz. It was a concern that the interaction between the off modulation of the thruster control system and the structural modes during the delta- maneuvers may cause undesirable high-frequency short pulse firings (thruster chattering), control performance degradation, and even structural damage to the solar arrays, if left unabated. The phase-plane controller for the thruster attitude control system was designed to abate these undesirable effects by employing hysteresis in the switching lines. The hysteresis was proven to be effective in addressing these concerns. This paper describes in detail the thruster pointing control system and its performance achieved on orbit, based on the telemetry data collected during delta- maneuvers, in comparison with analytical predictions.

Desert Storm: air assault communications

The development of the US Army's 101st Airborne Division (Air Assault) Signal Battalion's command and control communications system from base-camp communications system into a system that provided division offensive communications which spanned more than 1000 miles and supported air assault ground and air combat offense operations in Iraq during Operations Desert Shield and Desert Storm is discussed. The forward operating base used the AN/TRC-170 multichannel tropospheric scatter communication system as the backbone and multichannel tactical satellite communication as the pivotal means for follow-on movement. The systems deployed by the battalion for base camp communications, covering force communications, and offensive communications are described.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

MILSATCOM Architecture

The Military Satellite Communications Systems Office (MSO) of the Defense Communications Agency has recently prepared an architectural framework for the evolution of military satellite communications systems through the end of this century. The realization of the goals of the architecture should provide significantly enhanced military utility to three functional classes of users. The strategic forces would be directed and managed through a two-way, highly survivable, jam-resistant Strategic Satellite System (SSS). The Tactical Satellite System (TACSATCOM II) offers a jam-resistant, low probability of detection, communications system for employment of ground mobile forces as well as tactical Naval and Air Forces. The future Defense Satellite Communications System (DSCS III U/IV) will provide the high data-rate users with increased jam resistance to perform their missions. These satellite systems will use higher frequency bands (EHF), on-board processing, and improved antenna techniques. To implement the EHF technology in a coherent fashion, the MSO has also prepared a Technology Development Program Plan which identifies and plans for the needed R&D efforts.

The Tactical Communications Satellite

Early in 1969 the U. S. Air Force placed into synchronous orbit the largest communications satellite built to date. This vehicle, the tactical communications satellite (TACSAT), together with a variety of ground terminals, is designed to test experimentally and develop tactical communications concepts for all military services. This paper describes the spacecraft design focusing on the communications repeater. Measured performance characteristics affecting communications utilization of the spacecraft are presented.

A Family of SHF Tactical Satellite Communication Ground Terminals

On February 8, 1969, an experimental tactical communications satellite, TACSAT I, was successfully placed in synchronous orbit at the equator off the coast of South America. This paper concerns itself with a family of SHF tactical satellite communications ground terminals utilizing the SHF capability of that satellite. The material presented provides the system concepts necessary for the understanding of the ground terminals, their relationship to the satellite, and some insight into the design problems encountered during the development of a family of five types of terminals. The system concepts are presented in terms of communication modes, frequency assignments, and implementation of the respective modes. The beacon system for frequency control and signal acquisiticn siticn is described along with the factors involved in design of equipment implementing the analog FM, the alert message, frequency hopping, and, differential phase-shift keyed (DPSK) modes. The final configurations of each of the five terminals are described and illustrated through photographs and generalized block diagrams, and the capability of each is briefly outlined.