Abstract: Video conferencing, wherein the outputs of a plurality of television cameras at one location are transmitted to a second location so that parties at the first location are perceived as present by parties at the second location, has received some attention directed toward bandwidth reduction. The subject invention relates to an improved video conferencing system for reducing bandwidth by advantageously applying temporal resolution and spatial reduction to a video picture provided by each camera. The temporal resolution of a picture from one or more of the cameras can be automatically adapted to a control signal, for example, to a speech level control signal so as to advantageously interleave and to give priority to a picture from one camera over a picture from other television cameras. The spatial reduction of each picture obtains by transmitting and displaying less than the total picture, illustratively the middle two-thirds of the picture from each camera.

Abstract: A digital speech interpolation (DSI) system advantageously utilizes speech inactivity time to reduce the bit rate by compressing digital characters from a plurality of trunks onto a lesser plurality of channels. A signaling arrangement is typically employed therein to signal a receiver as to the activity of a trunk. If the number of active trunks exceeds the number of channels, an overload may exist. Known arrangements for mitigating overload typically include apparatus responsive to an activity signal for truncating one or more bits from the digital characters and for transmitting the truncated characters. Unfortunately, quantization noise is increased and digital precision decreased in such arrangements. The hereindisclosed system includes an improved automatically adaptive arrangement for advantageously incorporating nearly instantaneous companding (NIC) and priority trunk rotation in a plurality of frames, called a multiframe.

Abstract: Known tone detectors are adversely affected by various signaling tone distorting sources, including noise as well as talk-off due to tone-like speech, e.g., due to averaging of speech frequencies over a detection interval. As a result, improper tone detection often occurs. This problem is mitigated by dividing a detection interval into a plurality of detection sub-intervals which are then concatenated for tone detection. Detection of the desired tone in at least a predetermined number of concatenated sub-intervals is interpreted as the presence of a valid tone. Conversely, absence of detection of the desired tone in at least a second predetermined number of concatenated sub-intervals is interpreted as the absence of a valid tone.

Abstract: An analog-to-digital counting encoder or a digital-to-analog counting decoder for a pulse code modulation signal typically requires a function generator using precision components to generate a piecewise linear comparison signal corresponding to a segment companding law. As a result, nonproportional component change introduces nonlinear distortion in the encoded or decoded signal. To mitigate nonlinear distortion and to provide a less expensive digital signal processing arrangement, the invention resides in an improved nonprecision component function generator. The function generator includes two serially connected integrators which are advantageously switched in a complementary fashion to provide the comparison signal.

Abstract: In PCM and DPCM systems, a Hadamard orthogonal transformation of picture element signals is known to offer a means for reducing the bit rate for transmission of the signals. The first Hadamard coefficient, called H.sub.1, equals the sum of the picture element signals. Accordingly, still further reduction in the transmission bit rate can be achieved by efficiently coding H.sub.1. The disclosed coder includes a control signal generator for providing a control signal corresponding to a predetermined function of the quantized Hadamard coefficient signals. Several illustrative arrangements are disclosed. In three arrangements, the respective control signals are employed to adaptively select one of a plurality of quantizers, the selected quantizer for coding H.sub.1. In a fourth arrangement, the control signal is employed to predict H.sub.1, the predictor control signal being thereafter used for coding H.sub.1.

Abstract: A data communications system designed to facilitate communications between digital computers typically routes fixed-length segments of data, called packets, through minicomputer packet switches located intermediate the digital computers. To mitigate the need for expensive minicomputer arrangements as the intermediate processor, the minicomputers are replaced by a low-cost, high-throughput, modular packet switch having an efficient control memory-queue control arrangement for moving a packet from one time slot to another as well as modifying the packet header as the packet is routed through the communications system.

Abstract: A digital data communication system typically includes arrangements for achieving synchronization of the digital data processed by the system. However, known synchronizing arrangements are usually inefficient with respect to the time required to achieve bit synchronization. To shorten the time required for synchronization of two bit streams, an improved synchronizer including a sequential store, a plurality of comparators, a circulating memory having a plurality of memory registers, and a control circuit is disclosed. A first bit stream is extended through the sequential store into respective first inputs of the plurality of comparators. Each bit of a second bit stream jointly feeds all respective second inputs of the comparators. Using negative logic, each comparator output is NANDed with a first memory register output and fed into a second register input. When all but one of the memory register outputs are set, synchronization is achieved.

Abstract: Apparatus for transferring coin deposit information from a coin telephone station to a telephone office, for example, a TSPS, is highly susceptible to acoustically coupled fraud. Acoustically coupled fraud is substantially obviated by an arrangement which intentionally interrupts the transmission facility periodically, thereby forcing errors in any acoustically coupled signals and causing their rejection at the telephone office. In addition, acoustically coupled fraud is obviated during transmission of coin deposit data to the office by disconnecting the coin station speech network from the transmission line during this time.