Abstract: This invention relates to apparatus and a method for controlling a Digital Access and Crossconnect System (DACS) from a connected toll switching system. All control messages from operations support systems (OSS) for making crossconnect changes in the DACS are first routed to the toll switch. The toll switch extracts information needed to update its database and sends a control message to the DACS. In addition, the toll switch responds to changes in traffic patterns, perhaps due to the loss of a transmission facility, to generate a crossconnect change message to the DACS to rearrange facilities for more optimum performance. Advantageously, the OSSs for DACS control and switch control is combined and the toll network is made more responsive to traffic pattern changes and to losses of transmission facilities.

Abstract: The disclosure relates to error/fault detection in signal processing systems such as those employed in a time division multiplex conferencer. The digital message samples (of the conferees) and the accompanying parity bits are delivered to a signal processor e.g., a binary arithmetic adder (10). The adder sums the message samples and this sum is coupled to a first parity tree (11), which in response thereto generates a first parity bit. The carries generated by the summing operation and coupled to a second parity tree (12) along with the message parity bits and the second parity tree generates a second parity bit therefrom. The first and second parity bits are compared (13) and if they differ a fault exists. Corrective action is taken immediately--the faulty conference "leg" is removed from the conference connection without affecting the remaining legs in the conference or any other conference.

Abstract: A time division multiplex conferencer for continuously summing and outputting digital message samples received from n subscribers in n respective time slots. Message samples collected from each subscriber of a conference connection are summed during a first time frame and outputted during a second time frame. The conferencing is carried out in real time under common control to provide one or more conference-type connections between two or more subscribers. The conferencer also has the ability to establish transmit-only or receive-only connections for one or more subscribers. The conferencing is conducted in a manner that is completely independent of time slot assignments within a frame.

Abstract: In a multilocation video conference system, contention for the video to be transmitted to the locations is resolved by employing so-called talker and graphics contention resolution processes. Both the talker and graphics contention processes may be overridden by manual selection of the video to be viewed at each location. In the talker contention process, the video to be transmitted is not switched until one and only one talker location is detected during a predetermined talker timing interval. In the graphics contention process, all requests for graphics transmission are rejected until one and only one graphics transmission request is detected during a predetermined graphics request timing interval. Once transmission of graphics has been assigned to a location, all other locations in the conference are transmitted the graphics video information until the location displaying graphics releases from the graphics transmission mode or there is a manual override.

Abstract: In a Multilocation Conference Terminal (MLCT), disruptions in the video being viewed which are caused by switching from one conference location to another are minimized by delaying switching of the video signal until a so-called get ready control signal is received from the conference location to be viewed. The conference location transmits the get ready control signal a predetermined interval prior to transmitting a so-called fast video picture update in response to a request from a Multilocation Conference Terminal (MLCT). Additional possible disruptions in the video are eliminated by minimizing the number of fast video picture updates that are used to serve a multiplicity of requests from other conference locations. When multiple MLCTs are employed in a conference, the MLCTs communicate to each other the video select modes of all the conference locations in the conference, i.e., a manual select mode or an automatic select mode.

Abstract: In a multilocation video conference system, conference locations are dynamically added to or deleted from an ongoing conference without disrupting it. This is realized by controllably enabling or disabling communications ports assigned to the conference locations in a Multilocation Conference Terminal (MLCT). Both audio information and control channel information transmitted from a conference location assigned to a port are monitored to determine if the audio information is satisfactory and if the control channel communication is "good". If the audio information is unsatisfactory, it is muted and selection of the video from that location as a one-and-only-one talker is inhibited. If the control channel communication is not good the video signal from the conference location is excluded from the conference.

Abstract: There is disclosed a general purpose linear time division multiplexed conference system for continuously summing and supplying digital message samples arriving in time slots within a frame. The conference system integrates both voice and data network conference connections and provides total isolation between the secondary legs of a data network connection. The host computer of a data conference connection is assigned to the lowest ordered time slot relative to the time slots assigned to secondary legs of the data conference connection. The summation of data samples accumulated from each leg of the data conference connection during a write cycle is modified during a next supply cycle after distribution to the host computer but prior to distribution to secondary legs. Modification is achieved by overwriting the summation with the data sample received from the host computer during the prior write cycle.

Abstract: There is disclosed a linear time division multiplexed time slot conference for continuously summing and outputting digital message samples received from n connected telephone lines respective to m sequential time slots. The conferencer processes 256 time slots and uses prefetching techniques to reduce memory requirements to allow the circuit to be integrated into a single chip. Besides establishing conference-type connections, the conferencer has the capability to establish broadcast and monitor connections. Message samples collected from each connected line of a conference connection are summed during a first time frame and outputted during a second time frame. The conferencer includes circuitry for detecting either positive or negative overflow which could result from the summation process, and in this respect, selects an alternate message for outputting.