Abstract: A station for use in a teleconferencing system is disclosed. The station includes an arrangement comprising a plurality of image sensing devices, each of which provides a sub-image. The sub-images are joined to form a single high resolution video display. Illustratively, the arrangement comprises a plurality of image sensing devices and one or more mirrors to insure that the fields of view of the image sensing devices are contiguous at all relevant distances. Alternatively, an array of image sensing devices may be utilized wherein the horizontal and vertical scans of the devices are cropped.

Abstract: A circuit board edge connector that utilizes alternating conductive (5) and non-conductive (6) segments of elastomeric strips (4) to provide discrete electrical conductivity between pairs of boards (illustratively 40 and 60). The disclosed structure maintains surface contact between boards (1) and associated elastomeric strips (4), and between associated elastomeric strips (4).

Abstract: A framer circuit which may be implemented as a single chip is disclosed. The framer circuit performs a number of functions in a DTDM network including generating trains of empty DTDM frames, enabling the writing of data packets into specific DTDM frames and the examination of header data in specific DTDM frames to generate signals for the control of peripheral circuits. The framer circuit comprises an input serial/parallel converter, a frame detection circuit, an output parallel/serial converter and a control unit comprising one or more finite state machines for generating proper control signals such as read and write strobes for data insertion and extraction.

Abstract: A mechanism is disclosed for resolving conflicts between input ports of a Batcher-Banyan Packet switching network that wish to transmit data packets to the same output port during a particular packet switch cycle. The input ports of the Batcher-Banyon network are connected in a serial ring. Bit positions on the ring represent output ports. Each input port having a data packet to transmit to a particular output port may reserve that output port before the start of the next Batcher-Banyan packet switch cycle by writing a "1" in the ring bit position corresponding to the output port to which the data packet is addressed. If the particular output port has already been reserved by another input port, the data packet is buffered.

Abstract: An optical fiber-ring network is disclosed. The network is capable of operating in the face of the failure of any single node regardless of the particular node failure mechanism, including stuck "on" and stuck "off" transmitters.Each node in the network comprises a main receiver, an alternate receiver, and a transmitter. The main receiver receives data from the immediately adjacent upstream node, while the alternate receiver monitors transmissions from the next preceding upstream node. Each node diagnoses the transmitter in its immediately adjacent upstream neighbor and its own main receiver. If either fails, the node switches from its main receiver to its alternate receiver to bypass the immediately adjacent upstream node, while the rest of the ring remains functional.

Abstract: The circuit (34) is of the type having an input section (12) and a shaping section (22). The input section includes a photodiode (14) and a transimpedance amplifier (16) with an AGC shunt device (19) connected between its input nodes (+,-). The shaping section includes, in order, an AGC amplifier (24), an equalizer amplifier (26), a buffer amplifier (42), and a filter (44). A controller (36) responsive to the photocurrent controls the impedance value of a dynamic impedance in the equalizer so that the frequency zero of the equalizer tracks the pole frequency of the input section as it changes in the course of changes in the value of its AGC shunt. This maintains the frequency response of the shaping section so that it continues to compensate for the frequency response characteristic of the input section. A trigger (52) responsive to the impedance value of the shunt activates the equalizer only when the shunt is active.

Abstract: An improved transimpedance amplifier allows an optical transmitter and receiver to be in close proximity to each other without fear of overloading the receiver. The improvement increases the dynamic range of the transimpedance amplifier and thereby the operating range of the receiver. A peak detector (22) at the output of an inverting amplifier (11) within the transimpedance amplifier turns on a field effect transistor (FET) circuit (23) when an AC component of an electrical signal becomes so large that the inverting amplifier would otherwise go into saturation. The FET circuit (23) acts as an AC shunt impedance at the input of the inverting amplifier and diverts the excess AC current to ground (30). Also, the FET circuit (23) acts as a DC resistance in concert with sense and sink current mirrors (21) and (24) to effectively divert an excessive DC component of the electrical signal away from the input of the inverting amplifier (11).

Abstract: Coins deposited in a coin telephone are collected or refunded by selectively discharging one of a plurality of capacitors (10,12) through a current limiter (46) for a period just long enough to operate the coin control relay (38) in the telephone. Use of this current limiter minimizes the drain of power from the remote terminal of a subscriber loop carrier system which derives all of its power from a telephone central office. A second current limiter (24) limits the rate at which the capacitors are charged.