Showing papers on "Telecommunications link published in 1985"

Satellite audio broadcasting system

Abstract: A satellite audio broadcasting system for network programming and broad-based advertising includes a network uplink facility and a plurality of local radio station downlink facilities. The system permits pre-empting of network audio by the local station at any time, but automatically and constantly monitors the local broadcast, comparing it to the network audio, and automatically records any periods of departure. Computers are employed at uplink and downlinks, and from time to time the uplink causes each downlink to transfer to it all data relating to such periods of departure for the subject period of time. Using the data this uplink can automatically compute billing to advertisers and payments to subscriber local stations based on the amount of advertising actually broadcast by the stations. Verification is thereby fully automatic and is substantially tamper-proof. Digital databursts preferably are transmitted via the satellite along with the network audio for separation, decoding and use at the downlink. Such data may contain, for example, a program pre-schedule for the coming day and/or simultaneous identifying information at the time a program or advertising is aired, for downlink logging, and individual accessing codes for network control or communication with specific downlink affiliates.

Satellite scrambling communication network using geographically separated uplinks

Abstract: @ A satellite scrambling communication network uses geographically separated uplinks to provide scrambled video and audio signals and descrambling control data to separated individual subscribers and to separated TV signal distribution systems. The network includes a business control center which provides a master data stream including individual subscriber address and encryption data and uplink channel allocation control data. There is a first satellite communication uplink for transmitting one or more television channels, as controlled by the allocation data in the master data stream, to a communication satellite. The first uplink adds to the master data stream supplementary data peculiar to those TV channel distribution systems which will distribute the one or more TV channels from the first uplink. The transmission at the first uplink, in addition to the one or more TV channels, includes the master data stream and the supplementary data peculiar to the first uplink. There are a plurality of geographically separated additional satellite communication uplinks, each including means for receiving the master data stream as transmitted from the first uplink via the communication satellite. Each additional satellite communication uplink further includes means for transmitting transmitting one or more TV channels, as controlled by the allocation data in the master data stream. The additional uplinks further include means for adding to the master data stream supplementary data peculiar to those TV distribution systems which will distribute the one or more TV channels from each additional uplink. Each additional uplink further includes means for transmitting, with its one or more TV its one or more TV channels, the supplementary data peculiar thereto. There are multiple individual subscriber receiver/decoders, each of which has an antenna for receiving the TV channels as transmitted by the uplinks via the communication satellite. Each subscriber receiver decoder is controlled by the master data stream. There are a plurality of geographically separated TV signal distribution systems, each with antenna means for receiving the TV channels from one or more of the uplinks. Each TV signal distribution system is controlled by the supplenientary data streams which accompany the one or more TV channels from each of the uplinks.

Fully interconnected spot beam satellite communication system

Abstract: A communication signal can be routed from any location in a spot beam satellite system to any other location within the spot beam system by simply choosing the proper carrier frequency for the uplink to the satellite The spot beams are fully interconnected without any need for active switching within the satellite An uplink signal received by one or more satellites in a particular orbit location may be routed, depending on its frequency, to any downlink spot beam A network control center located on the ground in one of the spot beam coverage areas receives signalling requests from all the spot beam coverage areas and assigns frequencies so that the desired routing can be established All of this is accomplished without any signal demodulation or active switching of circuit paths in the satellite

A High Performance - Wide Band - Diplexing - Tracking - Depolarization Correcting Satellite Communication Antenna Feed

Abstract: A wide bandwidth diplexing feed system consisting of a pair of multihole corrugated directional couplers and a dual-depth corrugated horn, has been developed for satellite communication antenna applications. The feed has capacity to handle any arbitrary dual orthogonally polarized signals and to incorporate in dependent depolarization correction for these signals in the downlink and uplink. It shows a very good isolation between orthogonally polarized signals at each reused frequency over the recently allocated bands which extend from 3.4 to 4.2 GHz in the downlink and 5.85 to 6.775 GHz in the uplink for fixed satellite systems. Two modular devices which operate for high or low frequency beacon to extract difference modes for tracking purpose, are also described. Based on beacon allocation, the suitable module can be conveniently incorporated in the feed system without disturbing the electrical performances at the communication links.

Two-Level Multiaccess Schemes for Packet Satellite Systems with Low Duty Factor Terminals

Abstract: A two-level packet satellite network architecture is proposed to provide efficient communications for a large number of low duty factor terminals. At the first level, disjoint subnets of prioritized users employ a minislotted alternating priorities (MSAP) protocol. At the second level, a time division multiple access (TDMA) or frequency division multiple access (FDMA) uplink, and a time division multiplexed (TDM) or frequency division multiplexed (FDM) downlink is assumed, with the satellite regenerating and reformatting the data appropriately. Examples with a large number of terminals show that the two-level schemes provide superior delay performance over single-level methods for wide ranges of throughput.

The Communications link analysis and simulation system (CLASS)

Abstract: The Communications Link Analysis and Simulation System (CLASS) is a comprehensive, computerized communications and tracking system analysis tool under development by the Networks Directorate of the NASA/GSFC. The primary use of this system is to provide the capability to predict the performance of the Tracking and Data Relay Satellite system (TDRSS) User Communications and Tracking links through the TDRSS. The general capabilities and operational philosophy of the current and final versions of the CLASS are described along with some examples of analyses which have been performed utilizing the capabilities of this system.

A Methodology for the Selection of Frequencies for Deep Space Telecommunications

Abstract: For each new deep-space mission it is necessary to select the radio frequencies that will be used for uplink and downlink communication The frequency selection has the objective of avoiding or minimizing the possibility of radio interference between existing and planned missions This paper presents a comprehensive procedure for the selection of frequencies for deep-space communications The procedure includes the possible effects of several existing missions on a new mission This is shown through an example of frequency selection of a new National Aeronautics and Space Administration (NASA) deep-spce mission using actual mission data

A Random Access Multibeam Packet Satellite with Buffer and Arbitrary Transition Overhead

Abstract: This correspondence reports the performance of a multibeam packet satellite using ALOHA type random access techniques. The satellite is assumed to provide an infinite buffer for successful packets on the uplinks of various beam zones. The transition overhead of a downlink transponder can be arbitrary. A TDMA frame is organized according to the traffic demand of each zone. This work is an extension of [1].