Remote observatory access via the advanced communications technology satellite
Abstract
The remote access of the Apache Point Observatory (APO) at Sunspot, New Mexico, by using the Advanced Communications Technology Satellite (ACTS) is investigated. This opportunity arose as a result of the announcement by NASA proposing investigations that demonstrate communications techniques and services and verifying technology implementations by using ACTS. An end-to-end simulation testbed has been developed for the underlying satellite communication network, which is composed of the APO's LAN, the remote observer's LAN, and part of the ACTS Low Burst Rate 2 (LBR-2) network which serves as the internetworking medium between the two LAN's. This is accomplished by using COMNET II.5, a communication network oriented tool for designing, developing, and executing simulations within one user interface. Performance tests at different network elements have been performed to measure processing delays. Specifications and/or salient features of network functional subsystems have been used to reach a high degree of accuracy with the real model. Additional features taken into consideration are the traffic model of the telescope, the TDMA frame structure, and the potential protocols for end-to-end delivery of data. Based on the testbed, a detailed output report determines factors in the network, such as access possibilities between APO and major astronomical centers and observatories using the ACTS; latency between the APO and the remote user; TDMA frame capacity requirements to support network data under various conditions; buffer sizes required in various network elements to support data transfer; optimum protocol configurations for end-to-end transport; potential ACTS terminal limitations on the data transport process; identify bottleneck areas and conditions under which they occur in optimizing such a network; and potentials for growth in the APO data source capacity, using the ACTS-type of frame structure.
- Publication:
-
Ph.D. Thesis
- Pub Date:
- 1992
- Bibcode:
- 1992PhDT........41G
- Keywords:
-
- Acts;
- Astronomical Observatories;
- Local Area Networks;
- Network Control;
- Performance Tests;
- Remote Control;
- Satellite Communication;
- Computerized Simulation;
- Data Transfer (Computers);
- Protocol (Computers);
- Time Division Multiple Access;
- Communications and Radar