Abstract: A system for monitoring a patient located on an item of furniture such as a bed is disclosed. The system includes a pneumatically actuated switch for providing a signal circuit to notify of undesired movement of the patient beyond a predetermined range. The pneumatic switch is responsive to a pneumatic pulse which is released from an armable pneumatic pressure generator having a spring loaded plunger and piston combination. The piston is maintained in an extracted and armed position through a releasable clip positionable within a notch in the piston and attached to the patient by a length of cord.

Abstract: A locating and monitoring system includes transmitters worn by a person, animal, or equipment to transmit an unique identification code while moving about a facility. The code is transmitted by pulse bursts at diverse times during predetermined time intervals to prevent synchronization with resident signals in the facility. Receivers in the walls or ceilings of the facility respond to the infrared radiation of the pulse bursts and validate the identification code by a checksum of the code through a comparison with a checksum transmitted with the code. The receivers deliver validated codes to arbitrators and receive back signals indicative of the level of an individual assigned to a class wearing the transmitters. Signals from the receivers are received by arbitrators which forward the codes to a CPU for recording start and stop events indicative of movement by transmitters into and out of the reception range of the various receivers.

Abstract: An improved electronic hybrid for coupling signals between two wire and four wire transmission circuits. The hybrid includes a pair of amplifiers associated with a pair of terminating impedances which are serially connected between the amplifier outputs and the two wire port. The amplifiers driving the two wire port through the terminating impedances are biased to couple a dc potential to the two wire line whereby the terminating impedances serve as battery feed resistors. Each amplifier-impedance arrangement includes a feedback circuit connected from the junction between the impedance and the two wire port and an input of the amplifier for providing positive feedback for the amplifier so that the output impedance of the hybrid is maintained at a desired level using battery feed resistors of smaller value than heretofore required. The result is the ability to drive longer loops through the smaller series impedances while at the same time exhibiting the desired terminating impedance.

Abstract: Automated telephones with electronic circuits for outputting dial digit sequences respectively corresponding to different ones of a plurality of user's switches when each switch is momentarily actuated. The circuits permit speed dialing of (i) directory numbers, (ii) tandem sequences for accessing outside centers and specific line numbers, and (iii) access or feature codes. The apparatus is characterized especially by devices to create automatically loop breaks to simulate either a hook flash or a re-seize on-hook condition in certain circumstances and despite the fact that the telephone remains off-hook. By simple wire connections between a master or "secretary's " telephone and each of the members' phone sets within a limited group, intelligence signals are interchanged to provide "key line group" action without an elaborate, separate "control box" and even though each telephone of the group is served by the central system only via its own two-wire line.

Abstract: A DTMF signal receiver, for telephone systems, includes an amplifier with automatic gain control for receiving and amplifying DTMF and audio signals. A series of bandpass and notch filters receive the output from the amplifier for producing bandpass and notch outputs in response to the DTMF frequencies. A detector receives the bandpass output from each of the filters to produce a signal representing the presence or absence of a signal of each DTMF frequency in the amplifier output, and a DTMF decoder receives the signals from all such detectors and produces output signals in response to simultaneous detection of preselected pairs of DTMF frequencies. A voice guard circuit receives the notch output from the last filter in the series and compares the amplitude of that notch output with a threshold level to produce a disable signal whenever the amplitude of the notch output is greater than the threshold.

Abstract: A faceplate assembly is provided for use in printed circuit board assemblies comprising a printed circuit board with electrical contact surfaces, and a housing frame with slotted guide rails to receive the circuit board, and edge connector means fastened to the housing frame and displaced at the end of the guide rails. The faceplate assembly includes insertion, extraction and positive latching means molded as an integral part of the faceplate. The faceplate body extends substantially the entire length of the printed circuit board edge and is pivotally mounted to the printed circuit board near one corner thereof. The insertion/extraction means, located on the pivotal end of the faceplate body, is actuated by manual pivotal movement of the faceplate thereby causing the insertion/extraction means to coact with a housing frame U-channel to thus effect engagement or disengagement of the printed circuit board electrical contacts to or from the housing frame edge connector contacts.

Abstract: A station-to-station supervision system for a telephone system has a dual tone multiple frequency (DTMF) signal generator connected to the transmit line at each subscriber station, and a standard audible signal generator is connected to the receive line at each subscriber station for generating dial tone, ringback tone, reorder tone and busy tone in response to supervisory DTMF signals. Control means associated with each subscriber station effect the generation of a dial tone disable DTMF signal from a calling station in response to the combination of an off-hook condition at the calling station and the absence of a DTMF signal from any other station in the system; a busy tone command DTMF signal from any given station in response to the combination of an address signal for that station and an off-hook condition at that station; and a ringback tone command DTMF signal from any given station in response to the combination of an address signal for that station and an on-hook condition at that station.

Abstract: A current regulator for a pulse code modulated (PCM) transmission line is interposed between a voltage potential and a load (consisting of repeater amplifiers along the PCM transmission line) for limiting the current flow to the load. During normal operation, the regulator provides a relatively low impedance path from the voltage potential to the load through a series pass transistor and a sensing resistor. During an overload condition, which is sensed by the sensing resistor, the series pass transistor is deprived of base drive thereby providing a high impedance path with an accompanying increased voltage drop across the series pass transistor of the series regulator. This voltage drop is used to drive a timer which turns the series pass transistor off and on, with a low on time or duty cycle, in order to minimize power dissipation during the overload condition.

Abstract: A program plug formed by a circuit board with interconnected sockets which engage conventional wire-wrap posts on the back panel of a circuit shelf to provide a convenient, accurate temporary interconnection to facilitate circuit testing and expansion.

Abstract: A hybrid bridge circuit has a feed amplifier and an auxiliary resistor connected in series with the output of the receive amplifier between the amplifier and a node of the bridge so that signals from the receive amplifier are transmitted through the two-wire line port in the bridge to the auxiliary resistor and a resistive leg of the bridge, and signals from the two-wire line are transmitted to both the node V1 between the two-wire line port and the adjacent resistive leg of the bridge and the node V2 between the compensating network in the bridge and the adjacent resistive leg of the bridge. A differential transmit amplifier differentially receives inputs from the nodes V1 and V2 so that the differential amplifier produces a partially equalized output signal corresponding to the difference between the voltages at the nodes V1 and V2. The resistance values R1 and R2 of the two resistors legs of the bridge, and the impedances Z.sub.c and Z.sub.

Abstract: A switching regulator generates controllable pulses from a primary d-c. voltage source and then smooths the pulses to form a d-c. output that varies according to the changes in the pulses. A reference voltage source establishes a d-c. reference signal that varies in magnitude with any variations in the magnitude of the d-c. output but with a substantially constant differential in magnitude between the reference signal and the d-c. output. A voltage or current sensor generates a signal that varies in accordance with changes in the voltage or current level of the d-c. output, and a comparator detects the difference between the reference signal and the signal from the sensing means to produce a control signal that varies according to changes in the difference between the two signals. The pulses that form the d-c. output are adjusted in response to the control signal to maintain the output at a regulated voltage or current level.

Abstract: A telephone transmission system has repeaters spaced along both the transmit and receive legs of the transmission line, with a power supply for the repeaters including a current regulator having positive and negative supply lines connecting the power supply to the two legs of the transmission line. Current surge protectors are connected from the two legs of the transmission line to ground. A pair of current sensors responsive to the current levels in the positive and negative supply lines, between the power supply and the current surge protectors closest to the power supply, produce output signals representative of the respective current levels. A control signal generating means receives the output signals from the current sensors and produces a control signal in response to a deviation of the higher current in the supply lines from a preselected reference level. The control signal is supplied to the current regulator to maintain the higher current level in the supply lines at the preselected reference level.

Abstract: A framing circuit for a pulse code modulated, time multiplexed data receiver provides terminal framing by first detecting a predetermined terminal frame bit code and then checking for false framing by utilizing a false framing detector to count the number of times a particular pattern in a signaling frame bit code occurs. The false framing detector is enabled after terminal framing of the receiver has been accomplished. The false framing detector thereby provides a cross-check between the terminal frame code and the signaling frame code to assure that the receiver has not erroneously framed on a 2 khz interference tone. The cross-check occurs during data reception after terminal framing so that the false frame detector does not delay reframing under ordinary circumstances.

Abstract: A telephone conference system includes a conference bridge for coupling multiple conference ports associated with corresponding conference stations. The bridge includes means for summing incoming signals from all the conference ports and supplying the summed signals to all the conference ports. A differential amplifier is connected to each of the conference ports and differentially receives (1) incoming signals at the corresponding conference port and (2) the output of the summing means so as to cancel from the output of the summing means any signal received by the summing means from the corresponding conference port. Thus, the differential amplifier passes only that portion of the output of the summing means that is received from conference ports other than the particular port to which that differential amplifier is connected.

Abstract: A miniature multi-impedance transformer module specially adapted for use in telephony. In the preferred embodiment a pair of multi-winding transformers and a coil are configured to have connecting pins projecting both above and below the bodies thereof. The upward projecting pins are inserted in a printed circuit board carrying a plurality of connectors in a predetermined array. This assembly is installed in a miniaturized case and potted in place with the lower projecting pins extending below a mounting surface of the case. The lower surface and the downward projecting pin are adapted for ready mounting on a second printed circuit board. The connectors at the top of the module receive shorting plugs for selectively connecting the windings of the transformers and coil to provide impedance matching in telephone equipment. The miniaturized board mounted modules are readily adapted for high density rack mount applications.

Abstract: A precision capacitor multiplier connected in a communication circuit for balancing transmission facility impedances. The circuit requires only a single precision capacitor, and utilizes a plurality of precision resistors selectable to cause the circuit to exhibit one of a plurality of precision capacitance values.

Abstract: A ground start loop current detector is used to monitor the loop current in a telephone subscriber loop when the subscriber requests service by grounding one line of the loop (ground start), when a busy subscriber discontinues use by opening the loop, and when a called subscriber answers in response to ringing by closing the loop. In order to operate in the presence of longitudinal (common mode) interference currents in the loop, especially in the ground start situation where only one line is monitored, the detector incorporates a differential amplifier which has its inputs connected to the loop through transformer windings that are phased so as to equalize the effects of longitudinal currents on the inputs of the differential amplifier.

Abstract: A multi-channel digital echo suppressor wherein analog signals on a plurality of paired transmit and receive lines are sampled and digitized to form an interleaved sequence of parallel digital words. The interleaved digital words are accumulated for a predetermined period to form accumulated sample sums in sequence for each of the respective transmit and receive lines. Means are provided for segregating the receive channel accumulated samples from the transmit channel accumulated samples and bringing the samples for the respective channel pairs back into time correlation. The receive line accumulated samples are sequentially compared against a predetermined reference for producing suppression control signals which are routed to respective suppression controllers for the various channels.

Abstract: An LED mounting retainer and a printed circuit board display using such retainer for firmly mounting LED's on a printed circuit board with the LED axis parallel to the board and spaced at a precisely determined standoff distance from the board. The retainer is a unitary injection molded plastic element having a body and a locking member joined by a hinge. The body has a recess for receiving the LED, the recess having apertures for allowing the LED leads to project therethrough. The locking member in being pivoted to a locked position engages the leads to bend them about 90.degree. from their initial orientation, causing the leads to project below a mounting surface on the LED retainer, to produce a right angle indicator assembly.

Abstract: An end mark controlled switching system including a crosspoint matrix and a plurality of single ended junctors for linking paths within the matrix. The single ended junctors are adapted to link matrix inlets by firing crosspoints associated with such inlets into a common matrix outlet thereby using the matrix outlet itself as the link. The single ended junctors include means for refiring linked paths to allow insertion of additional inlets into existing connections.