Abstract: A communication switching system in which control functions are distributed homogeneously, as opposed to being distributed by individual function, throughout the system. A plurality of controllers are coupled to a time division multiplex (TDM) bidirectional bus. Each controller includes a microprocessor to perform control functions. An interface element on the controller accesses the TDM bus while a switching element on each controller controls access between the interface element and the microprocessor. The switching element and interface element include storage areas which are double buffered to allow for more efficient operation and use of the memory space. The TDM bus is divided into a plurality of time slots. Each controller is assigned certain of the time slots and utilizes those time slots to communicate with other controllers. The system includes provisions for dynamic allocation of time slots.

Abstract: A method and device for phase synchronization for use particularly where a fixed internal clock signal generator is used for both receive and transmit functions.The phase difference between the incoming pulse train and a fixed internal framing clock is detected by a counting circuit which provides an output signal indicating the interval time of the phase difference. A delaying means coupled to the incoming pulse train delays the same in response to the output signal for the time indicated thereby and provide synchronism therebetween.

Abstract: Simple and reliable decoding of T-1 type pulse code information is achieved by combining a fast-acting recirculating frame recovery circuit with a simplified signal output register. The frame recovery circuit uses a recirculating 386-bit control word in which all positions which cannot be the main-frame bit position are continuously recorded by the continuous comparison of pairs of incoming data bits spaced 386 bits apart. Following a sufficient number of iterations of the control word to statistically identify all 385 non-main-frame bit positions with a high degree of probability, the remaining unidentified position is read out as the main-frame bit position, and is used to reset the frame clock generator.

Abstract: The standard D3 signalling frame bit pattern of a T1-type PCM telephone system is modified to provide a pattern in which (4n-3) separate low-speed data channels can be transmitted in a superframe consisting of 12n frames of the PCN carrier (n being a positive integer), without requiring a separate synchronization detector for superframe synchronization. Simple self-synchronizing circuit means are further disclosed for multiplexing a large number of essentially steady-state signals onto the low-speed data channels, and for positively detecting the onset and cessation of each steady-state signal, independently of the onset and cessation of any other steady-state signal, once in each group of k superframes, where k-1 is the number of steady-state signals being multiplexed.

Abstract: A switching system is disclosed for the concentration of a plurality of telephone lines onto a lesser plurality of intermediate trunks, wherein an independent processor is included at both ends of the concentrator system. These processors communicate with each other over a randomly chosen idle trunk, thereby negating the need for a dedicated communication link between the processors. Each processor controls the switching functions at its end of the concentrator, independently monitors and retains trunk status, subscriber line status and system operational status, and provides system fault detection, diagnosis and recovery including communication to maintenance personnel of trouble codes based on the detected fault and its diagnosis. Manual interaction with the system is also enabled at either end of the concentrator system via display and input/output units or remote from both ends.

Abstract: Conventional PCM encoders are made capable of handling a much larger number of telephone channels than normally possible by varying the set-up interval of the encoder in accordance with the maximum signal level to be set up.