Abstract: A frame relay protocol-based earth station interface architecture provides full mesh connectivity for a relatively small number of network stations. The fundamental component of the architecture is a frame relay protocol-based switch, which employs a network interface ‘frame relay’ standard to define the multiplexing of multiple virtual ports across single physical communications port. Through address and control fields of its connectivity control software, the frame relay protocol-based switch can be dynamically configured to provide multilayer addressing and device selectivity, thereby enabling point-to-point connectivity of multiple terminal devices, such as a plurality of audio circuits, to be effected via a single port. Dial codes on the station side of an audio signal multiplexer link are translated into frame relay addresses (data link connection identifiers) that are added to each frame of data for routing through the network.

Abstract: A demand-based connection management satellite communication network includes a plurality of geographically distributed earth stations, each earth station having a frame relay protocol-based switch for interfacing message signals between terminal devices and modem unit. One of the earth stations is a hub station whose modem unit includes plural demodulators tuned to carrier frequencies transmitted from other, remote stations. Each remote station has at least one hub-programmable demodulator and/or a programmable modulator. When an originating station receives a request from a terminal device for connectivity with a terminal device at a destination station, it transmits a connectivity request message to the hub station. In response, the hub station checks a demodulator and/or modulator frequency assignment database for demodulator availability.

Abstract: A precision, waveguide-configured, bandstop filter comprises a substrate formed of a conductive material capable of being die cast. To facilitate manufacture and assembly, the substrate is preferably formed as a pair of symmetrically shaped substrate halves which, when mated together, define an interior filter structure that performs the required bandstop filter function. Each substrate half is configured to have a generally longitudinal slot that extends from a planar mating surface and effectively forms one half of an interior longitudinal waveguide section through the filter. Transverse to and located at spaced apart locations along the longitudinal slot are a plurality of channels, which define parallel conductive surface webs that extend from opposite sidewalls of the longitudinal slot. The channels serve as distributed, diametrically opposed pairs of lumped parameter tuning elements of the bandstop filter. A first end of each web forms a portion of a conductive sidewall of the longitudinal slot.