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【范围】
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This SAE Aerospace Information Report (AIR) will examine network aspects of open and
shorted stubs, line reflections and bus loading due to network changes. Single network
level is assumed, that is, no carriage store hierarchical levels. However, two passive
network coupling variants called "branched bus" and "branched stub" will be introduced that
possibly could be used in a stores management network.
This report assumes familiarity with MIL-STD-1553B.
1.1 Purpose:
This document summarizes the results of hardware tests on simulated weapon data bus
networks utilizing MIL-STD-1760 (Reference 2.2.1).
Unique to this application is the fact that the network is reconfigurable by connecting
together mission dependent MIL-STD-1553B (Reference 2.2.2) store remote terminals
(RT)s at artificial network breakpoints. Further, during normal data bus operation the
weapon RTs are physically removed from the network. That is, in-flight weapon
separation from aircraft results in "open stubs" on the bus network. See Figure 1. All this
gives rise to changing network conditions, stubs exposed to harsh environments (such as
during rocket motor firing), noise interference, interoperable store requirements for
US/NATO military services and controversy about the effect of "open stubs" on bus
performance.
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