Abstract: A test probe cleaning apparatus for a test probe fixture having a multitude of test probes protruding therefrom, comprises a pan for containing a cleaning fluid, an upstanding brush in the pan, and a carriage for holding an inverted test probe fixture. The carriage is movable over the brush so that the test probes can be passed through the brush to be cleaned thereby. In a preferred embodiment, an arrangement is provided for gauging the height of the test probes. The height of the carriage can then be adjusted to match the height of the test probes. The apparatus simplifies the cleaning of test probes in the high technology industry.

Abstract: The invention provides a very fast distributed frame relay switch. Each switching element is tied to each other switching element using LAN like FDDI technology. Frame relay packets arrive into the switch via lower speed TDM based trunks and can either be switched locally within the same switching element or can be switched to a remote switching element via the FDDI bus. The switching elements themselves reside in a TDM based multiplexer, thus can utilize existing TDM interfaces.

Abstract: A wiring hub for interconnecting a plurality of switching units, includes a plurality of interface modules for connection to respective external switching units in a dual-attached connection, and a dual FDDI ring interconnecting the interface modules. The interface modules include a switching element operable to bypass each switching unit or insert it on the ring in a dual-attached connection. The switching element automatically switches the interface module to its bypass state when a switching unit is disconnected from the wiring hub.

Abstract: A method of managing an interface to an internal message pipe, such as an FDDI bus, comprises sending a status enquiry message to request the status of each PVC having a DLCI in a specified range, receiving a subset status message containing sequence exchange numbers corresponding to the last status message sent out, updating the contents of a station's PVC's in response to the received subset status message, and propagating PVC status changes between entities on the pipe.

Abstract: A data transmission network includes a plurality of data processing devices for connection to local data sources. The data processing devices assemble data packets from the local sources into frame relay packets. A plurality of interconnected network nodes are connected to the data processing devices. Point-to-point frame relay links (FRLs) are established between nodes of the network. Frame relay switches installed at the nodes for switch frame relay packets between successive frame relay links through the network. Frame relay paths (FRPs) are established between endpoints of the network using a plurality of successive established frame relay links.

Abstract: An arrangement is disclosed for providing switched access to a packet-based network. The arrangement comprises an ISDN switch connected to terminal units via ISDN links, a frame relay switch, and a TDM trunk connecting the frame relay switch to the ISDN switch. The TDM trunk has circuits that constitute a hunt group for switched access to the network and perform signaling termination.

Abstract: A method is disclosed for transmitting super-rate data signals having a bit-rate higher than a predetermined bit-rate through a digital data transmission system normally providing channels having the predetermined bit-rate. The channels are subject to different propagation delay characteristics through the system. The method, comprises allocating a group of k channels in the data transmission system as a virtual channel for the transmission of the super-rate signals; dividing the super-rate signals into n sub-signals, where n.ltoreq.

Abstract: A speech processing system having an encoder comprising apparatus for receiving successive samples of PCM (pulse code modulated) encoded speech signals and apparatus, for applying sequential groups of the PCM encoded speech signals as primary vector signals to an encoder code book memory for selecting code words stored in the memory most closely approximating the vector signals. Apparatus is included for outputting to an output line the selected code words at a first bit rate. Further apparatus connects the selected code words to converted vector signals. The primary vector signals and converted vector signals are compared and difference signals result. The difference signals are quantized error signals are provided thereby.