Abstract: To reduce the possibility of a data-induced latching loopback, a digital data services device integrates one or more digital control code-based filtering routines into a test code sequence-based latching loopback scheme. The filtering routines include a ‘garbage’ byte detection routine, a ‘protected loopback’ routine, and a ‘preamble’ routine. The ‘garbage’ byte detection routine is an intra-loopback establishment filtering routine that limits the type of customer data that may be received between sequences of repeated control bytes of a valid latching loopback sequence. The ‘protected loopback’ routine is a flag byte-based filtering routine for frame relay data, which controllably disables latching loopback for a prescribed period of time, whenever a predetermined character associated with frame relay customer data is detected.

Abstract: To prevent the occurrence of an anomaly on a single data-sourcing slave channel from causing continuous transmission on that channel and thereby tying up the entirety of a multipoint network, a signal transmission quality monitoring mechanism is incorporated into the office channel unit of each data-sourcing channel. The signal transmission quality monitoring mechanism controls the participation of each monitored digital communications channel on the basis of a measure of the quality of digital signals received from each monitored channel. The control software of each slave channel's office channel unit is configured to include a bipolar violation detector which monitors the channel for the presence of errors exhibited as bipolar violations of alternate mark inversion (AMI)-formatted digital signals. In response to the occurrence of a prescribed number of illegal bipolar violations within a predetermined number of received signals (e.g.

Abstract: A method and apparatus for making a plurality of arc-spot welds in a predetermined pattern is disclosed. A plurality of welding torches are mounted upon a carriage which is longitudinally movable relative to a work piece. The work piece is supported by work piece supports which are vertically movable to allow exit of a completed work piece and insertion of a new work piece. A clamping assembly mounted above the work piece supports is movable toward the work piece to engage the work piece to hold it in place for welding, and is movable away from the work piece to allow exit of a completed work piece. The carriage is provided with a control which stops the carriage whereby the torches will be located at positions above the work piece corresponding to the desired pattern of arc-spot welds. The control preferably comprises a cam connected to the carriage which follows a track located on the frame which defines the welding pattern.