Nichols, M. H. (International Foundation for Telemetering, 1974-10)
Engineering formulae have been developed for estimating the performance of a telemetry system utilizing an NRZ PCM multiplex plus an FM/FM multiplex frequency modulating a carrier. These formulae have been checked against a laboratory simulation and the agreement is within 1 dB for the PCM and 1.8 dB for the FM/FM. About 1 dB of the 1.8 dB is tentatively accounted for on the basis of lack of symmetry of the carrier predetection (IF) filter used.
Rugg, Charles J. (International Foundation for Telemetering, 1980-10)
The Air Force Satellite Control Facility (AFSCF) came into being over twenty years ago, and since then has evolved into a satellite support network of major national importance. The present configuration of the AFSCF includes seven Remote Tracking Stations (RTS's) situated around the globe plus a central control facility, the Satellite Test Center (STC), located in Sunnyvale, California. (See Figure 1.) Ongoing plans will provide for significant upgrades and additions to the AFSCF network. Two of these which will have a major influence on the operations of AFSCF into the 1990's are the centralization of the real-time processing capability at the STC (Data Systems Modernization) and the implementation of a Consolidated Space Operations Center (CSOC) tentatively planned to be constructed in Colorado Springs, Colorado. These two upgrades to the AFSCF are discussed (see Figure 2) in detail elsewhere in these proceedings under their respective titles.
Moffat, Margaret H.; Hollander, Sidney (International Foundation for Telemetering, 1980-10)
Now in the planning stage by the Air Force Systems Command Space Division, the Consolidated Space Operations Center (CSOC) will be a secure, dedicated space control center that will provide the Air Force enhanced command and control capability in the late 1980's and 1990's. Tentatively to be constructed in Colorado Springs, Colorado for an initial operational capability date of mid-1986, the CSOC will include a Satellite Operations Center (SOC) and a Shuttle Operations and Planning Center (SOPC). The SOC, an integral part of the Air Force Satellite Control Facility (AFSCF) network and functionally identical to the Satellite Test Center (STC) in Sunnyvale, California, will perform its command and control functions with a modernized data system now under development at the STC, and will support its assigned AFSCF workload. Also, in the event of a catastrophic failure, the SOC will provide austere backup support for workloads normally assigned to the STC, and vice versa. Additional land is being acquired to accommodate the construction of facilities for major new space programs as required. The SOPC, functionally equivalent to portions of the NASA Johnson Space Center Space Shuttle Complex, will perform preflight, flight, and postflight operations necessary to satisfy DOD Space Shuttle vehicle payload mission objectives. The SOPC and the Johnson Space Center (JSC) will be interoperable so as to provide limited backup support for DOD or NASA Space Shuttle missions in the event of catastrophic or extended failure at either location. The development of the CSOC requires major architectural changes for both the AFSCF and NASA. These changes include an expansion of the current AFSCF wideband communications system; interfacing of the AFSCF and NASA communications networks; inclusion of a 32 megabit-per-second (or higher) telemetry processing capability for scientific experiments that will be flown during Shuttle sortie missions; and provision of systems to coordinate operations between Shuttle payload specialists and associated ground controllers.
Martin, D. H. (International Foundation for Telemetering, 1979-11)
Domestic communication satellite (domsat) systems in the United States have a history of 14 years. Currently, several systems are in operation and another will be in early 1981. In recent years, many papers have been published, each describing certain details of a specific system. In contrast, this paper presents an overview and comparison of all the systems. As a background to this survey, the U. S. domsat history is briefly reviewed. The system overview then begins with a look at the satellites. Their basic designs are compared pictorially and through tabular data. Communication subsystems are also compared. The survey then goes on to the terminals, the terrestrial parts of the systems. Representative terminal characteristics are discussed. Finally, the various communication services offered by these systems are described.
Mohanty, Nirode (International Foundation for Telemetering, 1987-10)
The phase tracking error of the reception of a QPSK signal transmitted in a severe fading environment is derived. The phase estimate derived from the phase lock loop (PLL) will be used by a binary phase shift keying (BPSK) receiver for the recovery of the data. The resultant probability of bit error is analyzed, and is shoen to be significantly improved when the phase of the transmitted signal is tracked by a PLL separately and utilized in the coherent detection.
Gerardi, F. R.; Otsuki, W. T. (International Foundation for Telemetering, 1978-11)
With the increase in complexity of military communications networks, a combination of spectrum spreading and error correction coding is typically required to provide adequate antijam protection. The specific system architecture utilizing these techniques is established in this presentation by performance requirements, system constraints, interface problems, and assumed jammer models. This presentation will describe various processing techniques with emphasis on their interactions and limitations. Two spread spectrum techniques for permitting operations in a jamming environment are considered: direct sequence (PN) and frequency hopping. The advantages and limitations of each technology will be discussed. The antijam capability of these spread spectrum systems can be improved by using various error correction coding schemes. These can (make more efficient use of the bandwidth allocation) as well as provide enhanced protection against pulse and tone jammers. The advantages, limitations, and constraints imposed on a communication system using various combinations of these techniques are discussed with particular emphasis on the system performance.
Hamilton, M. J.; Abbott, R.; Eggan, P.; Golber, D.; Hsieh, S.; Jordan, L.; Le, T.; Newcomb, R.; Sutton, S.; Ton, T.; et al. (International Foundation for Telemetering, 1992-10)
ASW-II (Advanced Satellite Workstation, Version II) has been developed and delivered as an operational prototype in support of the Ultra High Frequency (UHF) Follow-On satellite. It provides unified and coordinated real time reception and storage of satellite telemetry, display of both real time and stored telemetry, expert-system analysis of spacecraft status, and an information navigator system that stores and presents information about the spacecraft. The architecture is modular and reconfigurable, and it provides support for multiple analyst workstations. There are several unusual aspects of the design. The entire telemetry history of the satellite is regarded as a continuum by the user, with ASW-II automatically tracking and displaying contact periods. A "streams" mechanism organizes the telemetry in such a way that the user can interactively define new derived parameters and have them presented graphically. Both real time and archived data can be displayed simultaneously. The user has very flexible controls for all display interfaces using mouse and window technologies.
Mohanty, Nirode C. (International Foundation for Telemetering, 1985-10)
A demand access Satellite Communication System for multiple users has been analyzed. A number of channels, m 1, of each satellites are necessary to coordinate the self-served users to allow access to a satellite having s channels. m depends upon traffic intensity and number of top priority users. A waiting time period for a Poisson arrival and exponential holding time M/M/s system for “preemptive resume” discipline has been derived. There is a significant reduction in waiting time in accessing the channel and in transmission time over other access schemes. There is no waiting time for a top priority user, either in accessing the channel or in transmitting its messages, when the appropriate number of order wires is used.
Tsai, Kuang; Lui, Gee L. (International Foundation for Telemetering, 1999-10)
Gaussian Minimum Shift Keying (GMSK) is a form of Continuous Phase Modulation (CPM) whose spectral occupancy can be easily tailored to the available channel bandwidth by a suitable choice of signal parameters. The constant envelope of the GMSK signal enables it to corporate with saturated power amplifier without the spectral re-growth problem. This paper provides a quantitative synopsis of binary GMSK signals in terms of their bandwidth occupancy and coherent demodulation performance. A detailed account of how to demodulate such signals using the Viterbi Algorithm (VA) is given, along with analytical power spectral density (PSD) and computer simulated bit-error-rate (BER) results for various signal BT products. The effect of adjacent channel interference (ACI) is also quantified. Ideal synchronization for both symbol time and carrier phase is assumed.
The export option will allow you to export the current search results of the entered query to a file. Different
formats are available for download. To export the items, click on the button corresponding with the preferred download format.
By default, clicking on the export buttons will result in a download of the allowed maximum amount of items.
To select a subset of the search results, click "Selective Export" button and make a selection of the items you want to export.
The amount of items that can be exported at once is similarly restricted as the full export.
After making a selection, click one of the export format buttons. The amount of items that will be exported is indicated in the bubble next to export format.