Abstract: A coil assembly for use in an inductively powered transponder including a primary coil and a secondary coil wrapped around the same coil forming ferrite rod. The primary coil's leads are left floating while the secondary coil's leads are connected to the integrated identification circuit of the transponder. There are approximately three times as many turns to the primary coil as there are turns to the secondary coil. The primary coil is configured to self resonate at the operating frequency of the identification circuit when brought within range of an interrogator's magnetic field, thereby creating a voltage across the primary coil having a high source impedance.

Abstract: A one-to-one line switching system for switching between a hot line and a standby line in a one-to-one correspondence. To enable removal of a switching unit while in use, from a mother board for change over or repair, a pair of switching units (1 and 2 or 3 and 4) is provided at the transmitting part and at the receiving part, respectively, the earth element in one of the pair being connected to the other of the pair and the other of the pair being pulled up by a voltage, whereby, when one of the pair in use is removed, the other of the pair can pass the input signal.

Abstract: A contention control system for a shared communication medium has a separate control line. Functional modules contend on the control line for use of the communication medium. The system is simple and inexpensive, and avoids data collisions.

Abstract: A system gathers and displays information concerning status of a communications network without overloading the communications channels in the network. The monitoring system includes a monitor node, including an operator input interface. The monitor node is coupled to a first switching node in the distributed switching nodes of the network. The monitor node includes a first application maintaining topology data indicating the topology of the network and supporting a first protocol for updating the data with the first switching node. In addition, the monitor node includes a second application maintaining a list of alarm conditions entered in the node event logs in the network, and supporting a second protocol for updating the list with the plurality of distributed switching nodes. A third application runs in the monitor node for maintaining a monitor database indicating the configuration of the switching nodes as it is entered in the node configuration databases in the network.

Abstract: An access device at a public communications terminal enables an authorized user to gain access, via a connecting device, to an integrated services digital communications network. The access device includes a connecting device (2) behind a protective member (4) which permits access only after a check of the user's access authorization and a test of the correct functioning of the connecting device.

Abstract: A communications system has an active master node which transmits request messages in serial bit fashion on a data bus, and a plurality of responder nodes each of which receives the request messages on the data bus and may respond to a request message with a serial bit answer message. The possiblity exists that a plurality of responder nodes may provide concurrent answer messages forming a composite signal which the active master node may not be able to recognize as containing answer messages. A low pass filter is provided in the active master node which provides as its output only those pulses in the composite signal whose length is within a predetermined interval, typically from approximately a tenth to one half of the interval for each bit in the answer messages. A counter receives the low pass filter output and provides a collision signal to the associated master node if more than a preselected number of pulses within the predetermined interval are present.

Abstract: A battery saver type paging receiver includes an improved peak and valley amplitude detection type data limiter section with mode control operation thereof, digital word storage of acquired peak and valley amplitude values, and self tuning capabilities. More specifically, the data limiter section includes a controller for controlling the peak and valley detection circuits to acquire respective peak and valley amplitude values in digital word form in a first operational mode and to hold the peak and valley amplitude digital words in corresponding storage registers in a second operational mode. The controller may transfer the data limiter section into a third operational mode during which the peak and valley digital words may be altered a predetermined count to effect a self-tuning thereof. In one embodiment, the third mode of operation is effected during the transfer between the second and first modes of operation.

Abstract: The invention features a theft resistant security system for motor vehicles. The system has receptacle with a coupling coil. A SAW (surface acoustical wave) device associated with the receptacle for relative movement thereto is also provided. The SAW device has a code and its own coupling coil for interaction with the receptacle coupling coil. A testing mechanism is connected to the receptacle for determining whether the code of the SAW device is valid for operation of the motor vehicle. Problems of crosstalk and wave reflection may produce spurious code pulses in systems of this type. The invention provides techniques for eliminating or reducing these unwanted pulses.

Abstract: An electromagnetic transmission and detection apparatus comprising a transmission coil (20) for producing a high intensity electromagnetic field including one or more conductive windings (24) circumscribing a substantially polygonal volume of space having a central axis, and first and second receiver coils (22) disposed within the polygonal volume of space for receiving a low-intensity electromagnetic field transmitted from an external source. The receiver coils (22) are co-planar with the transmitter coil (20) and are disposed within the polygonal volume of the transmitter coil at positions which are polygonally, diametrical opposed to one another. The receiver coils (22) are electrically connected to each other in a differential circuit relationship such that the magnitude of electrical signals induced in the receiver coils (22) by uniform electromagnetic energy are substantially equal and opposite to one another.

Abstract: In a broadband signal switching matrix network having a cross-point matrix in FET technology whose switching elements, each controlled by a holding memory cell, are each formed with a series circuit of a switching transistor and of an input transistor, this series circuit (for a switching element situated in the through-connect state) forms a cross-point-associated, one branch of a differential amplifier whose other branch shared by the cross-points connecting to one and the same matrix output line is formed by an identical or similar transistor series circuit of an output amplifier circuit that is individually associated to the matrix output line. Thus, the matrix output line is connected to one terminal of an operating voltage source via a source transistor.

Abstract: A tree stand includes programmable circuitry allowing various messages to be played and lights to be illuminated responsive to actuation of various switches. The various switches are placed on the floor surface adjacent the tree stand and presents are placed over the various switches. Each switch is connected to a programmable control device designed to play a particular message responsive to activation of the switch. The message is designed to be specifically created for the recipient of the present which has been placed on the particular switch which has been activated.

Abstract: A selective call radio receiving system includes first and second receiving means (10 and 10') each having a memory (20 and 20') therein. Paging messages are received by both the first and second receiving means in accordance with their message receiving capabilities, including factors such as: range, memory size, and position relative to the radio frequency transmitter. The contents of the first and second memories (20, 20') are periodically compared (16 or 16') to determine whether a paging message has been missed. In this way, an individual has the best opportunity to receive each paging message transmitted to him.