VSAT technology, trends, and applications
Article Abstract:
One area of satellite communications technology is the deployment of very small aperture terminal (VSAT) networks for data, voice, and video communications. VSAT networks are usually private communications networks. Advantages are high reliability, distance-insensitive service, and the flexibility to handle growth. Because the network components are known and limited in number, it is easy to diagnose problems and maintain the network. The components of a VSAT network are the hub earth station, remote VSATs, and a network management system. The VSAT itself is a standalone unit that is installed at the customer's site. The VSAT is composed of an antenna, an outdoor unit, and an indoor unit. The disadvantages of a VSAT are the high cost of procurement and installation, the optimization toward large networks, and the lack of direct VSAT-to-VSAT communication. Work in Earth terminal technology, spacecraft design, and applications support should help overcome these disadvantages.
Publication Name: Proceedings of the IEEE
Subject: Electronics
ISSN: 0018-9219
Year: 1990
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Josephson shift registers
Article Abstract:
Shift registers based on Josephson junction technology operate as fast as 2.3 GHz, with niobium-based process technology offering as much as 30 GHz or more operating speeds. The operating speed of a shift register is often the limiter of system performance, though the simplicity of a shift register makes it faster than combinatorial circuitry. Major issues in the design of shift registers include the type of clocks (two- or three-phase; square- or sine-wave), use of flux quantization or Josephson junctions, the speed of the circuit as a factor of the switching speed, margins in the gate bias and bias uniformity. The shift register's speed can function as a benchmark for comparison of logic gate family performance. Examples of Josephson shift register design are briefly described.
Publication Name: Proceedings of the IEEE
Subject: Electronics
ISSN: 0018-9219
Year: 1989
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