Abstract: The sensitivity of an optically-based touch screen is substantially impro by adaptively establishing the detection threshold based on the peak trapped light measured over a number of frames on the screen being painted. In accordance with one feature of the invention, the peak trapped light from a target area painted on the screen is compared with a priorly established threshold as a way of determining that a target area is being touched by the user. In accordance with another feature of the invention, the threshold is modified in a way that compensates for possible erroneous touch indications due, for example, to bright spots on the screen.

Abstract: Battery feed circuits function to supply a predetermined current to the communication pair and include circuitry to counteract the effects of balanced longitudinal signals which appear on the communication pair. Prior art battery feed circuits use either expensive matched power resistors or matched and tracking current sources to provide both the dc current and the necessary balance. The subject battery feed circuit separates the two functions: a pair of poorly matched inexpensive power resistors provide the basic dc current; and associated pair of low power electronic circuits supply compensation signals to provide the necessary balance. The compensation signals are applied to the power resistors in a manner to obtain precision resistor (.+-.0.1%) characteristics from the inexpensive (.+-.5%) power resistors.

Abstract: A packet switching system is disclosed for transmitting variable length packets between system ports. Each byte of each packet has a special one-bit field for indicating whether the byte is the last byte of a packet. A "1" in this field specifies that the byte is the last byte of a packet and activates port control circuitry that changes the potential on a system control conductor to indicate that the system data bus is now idle and free for use by other ports.

Abstract: A voice-switched telephone circuit with center idle state improves bi-dirional gain control in loudspeaking telephones and thereby enhances the natural quality of interactive conversation. The voice-switched telephone includes: a transmit channel having a microphone and a three-state amplifier; a receiver channel having a three-state amplifier and a loudspeaker; and a hybrid circuit interconnecting the transmit and receive channels to a two-wire telephone line. The present invention is characterized by independent signal level detecting circuits for the transmit and receive channels. When the magnitude of the signal energy in the transmit channel exceeds a predetermined threshold, the transmit channel amplification is increased and the receive channel amplification is decreased by fixed equal amounts.

Abstract: The invention relates to a modular jack for telephone equipment. The jack has a pair of switch contact springs which are activated only when a plug of a specific shape is inserted into the jack.

Abstract: Apparatus for and a method of inserting circuit switch information and packetized data into different time slots of a time division multiplexed bus. A memory having a location individual to each time slot is written with information specifying whether the time slot individual to each location is to serve the circuit switch information or the packet data. The readout of each memory location during the occurrence of it's associated time slot controllably effects the application of either the circuit switch information or the packet data to the bus.

Abstract: A clock recovery circuit for recovering the clock from an incoming data stream. The circuit comprises a transition detector and a module 3 counter operating at three times the expected rate of the incoming clock. A clock pulse is generated by the counter one count interval after a transition is detected.

Abstract: A silicon micro-transmitter chip is housed within top and bottom closures snap-fitted together by legs and catches on the two closures. The chip is mounted between two acoustic cavities in the closures by a plate part of a configured metal sheet having other strip parts extending through grooves in the bottom closure to its outside where the strips are bent to provide arms for surface mounting the entire device on a printed wiring board. The sheet serves both as a continuous strap for effecting such surface mounting and as an electrode for connecting a terminal of the chip to ground. Other terminals of the chip are connectable to the board by flat leads passing through other grooves in the bottom closure to its outside where they are bent for surface mounting purposes. The housing formed by the two closures includes an adhesive impregnated gasket for providing an acoustic seal between the two cavities as to which the air pressures therein are equalized by a vent hole in the plate.

Abstract: The disclosed PBX integrity arrangement utilizes a specialized processing operation to provide an integrity check for communication devices and trunk facilities connected to a PBX. The integrity check determines (1) whether a user of a device or a trunk facility is permitted access to one or more PBX operations or (2) whether the PBX operation meets expected conventional PBX call establishment conditions. If access is prohibited or an atypical condition is present, this access or condition may indicate permission tampering, device or trunk facility misuse, malfunction or unauthorized PBX user activity. The occurrence of any one of the above conditions produces an immediate response which either remedies the occurrence or provides notification of the occurrence of the condition to a PBX administrator.

Abstract: A connector is disclosed that includes spring contacts (200) for making a solderless connection to other electrical conductors (310). Each spring contact (200) has a loop contact portion (230) that is supported so that its end regions (232 and 234) are restrained in a direction generally normal to the site of engagement of its arcuate contact surface (236) with the other electrical conductor (310). As a result, the main region (235) of the loop contact portion (230) is essentially rotated rather than compressed when pressed into engagement with the other electrical conductor (310). The desired contact force necessary for a good solderless electric connection is thereby provided.

Abstract: A cable connection unit includes a mounting arrangement for holding a variety of modular interconnection units for interconnecting a variety of communication cables. Each interconnection unit has the same length and a width which is an integer multiple of the width of the narrowest interconnection unit. The mounting arrangement can be mounted to a plate surface or to an apparatus enclosure having cable entry and exit opening and a moveable front panel. The apparatus enclosure perimeter includes a mortise and tenon to enable mechanical interconnection to one or more additional housing enclosures.

Abstract: A communication system includes a plurality of station sets each connected over two pair communication facilities to a control module. An adapter unit switchably connects an external data or voice device via a station set to either facility in response to a control signal from the control module. A data mode is established by sending a data mode request signal from the station set to the control module. An off-hook signal from a connected data device is used to request a data call. The control module signals to which facility the adapter is to connect the data call and outputs a unique visual on the data call facility. The control module prevents other calls from bridging onto or interfering with the data call. The system also permits a voice call on a facility to be converted to a data call on the other facility. Furthermore, a user can make a voice call over one facility while a data call is in progress on the other facility.

Abstract: An automatic call coverage feature arrangement for unattended PBX stations including attendant consoles. When an incoming call is received at an unattended station, a control processor monitors the number of ring cycles at the called station. The control processor automatically diverts the incoming call to a prescribed coverage station or facility following a prescribed number of ring cycles. Concurrently, the control processor activates an indicator to indicate that the feature is active. Thereafter, the control processor automatically diverts all subsequently received incoming calls from the unattended PBX station to the coverage station or facility. This feature does not require manual activation by a subscriber or an attendant, but is automatically activated in response to a first unanswered incoming call. This allows remote activation of the feature by a subscriber or attendant since all that is required to activate this feature is a first unanswered incoming call to the called station.

Abstract: Apparatus and a technique for echo cancellation is described in which the real and imaginary parts of an echo replica signal can evolve independently of each other. By removing the coupling heretofore found in cross coupled echo canceller structures, the echo replica obtained in conjunction with carrier-phase tracking circuitry can be a more exact duplicate of the real and imaginary components of a received echo containing signal. The echo canceller may include a plurality of subcancellers, each including at least four adaptive filters. Alternatively the filters within each subcanceller can be implemented by a suitably programmed digital signal processor.

Abstract: The subject communication system is an improved cellular mobile telecommunication system which provides business communication features to cellular mobile telecommunication customers.This is accomplished by using a business communication system as the switch element in the mobile telecommunication office. The master-slave relationship between the mobile telecommunication controller and the system processor that is found in the prior art is replaced by a peer-peer relationship. The mobile telecommunication control functions are handled by the mobile telecommunication controller while the call processing/connection control functions are handled by the system processor. Thus, the existing business communication call processing software can be used directly and any new business communication service provided by the business communication system is also available to the cellular mobile telecommunication customer.

Abstract: Improved alternate routing in a packet switching system is provided by inserting alternate routing control information into each packet and by storing alternate routing information at each network node. The stored information at each node includes a list of the available paths extending from the node towards all other nodes together with a list of available algorithms that can be used to select one of the available routes. The alternate routing control information in each packet contains postage information specifying the maximum number of nodes through which the packet is to travel. The alternate routing control information also includes a destination node index code identifying the destination node. The destination node index is used as address information by each node receiving a packet to read out the stored information at the node identifying the available paths and the algorithm to be used in selecting one of these paths for use in transmitting the packet towards the destination node.

Abstract: A flow control mechanism for a packet switching system that provides for the continuous dynamic control of station window size beginning with call setup and extending through the duration of the call. A station window size can be of a first magnitude at call setup time when system traffic may be low. The window size can be subsequently reduced to free up port buffer space as system traffic increases. This permits the serving of more calls during periods of heavy traffic.

Abstract: A modular, hierarchical local area network is realizable by using existing twisted pair wiring, for example, in a building together with several elements known as network access units and hub units. A network access unit is connected to a device (microprocessor, display terminal, peripheral device, other local area network, information systems network or the like) in the local area network to give that device access to and from the network. The network access device is designed for simple daisy chaining with other devices to form a node when devices are colocated in the same section or room in the building. The hub unit is the network building block which permits extensive expansion of the local area network. It provides a connection point for access units or other hub units, performs collision detection operations, if necessary, and serves as a loop-back point for the network.