Abstract: A line card shelf is disclosed. The line card shelf includes groups of line card receptacle connectors. Each receptacle connector has electrical contacts receiving corresponding line card contacts. Each group of receptacle connectors is coupled to at least two external connectors that terminate an inside or outside wiring cable bundle. Each receptacle in each group is connected to each external connector of the receptacle's group by a two-conductor signal path between a pair of electrical contacts in the receptacle and a unique pair of external electrical contacts in the external connector.

Abstract: Methods and apparatus for conserving power in terminal units that transmit and receive modulated data over a communications loop that is shared with voiceband telephone equipment are disclosed. The methods include monitoring the loop to detect a shut-down condition and reducing power consumption of certain of the electronic circuits in the terminal unit upon detection of a shut-down condition. The methods also include monitoring the loop with a monitoring circuit to detect a resume signal outside the voiceband frequency range on the loop and restoring power to the electronic circuits when the resume signal is detected. The apparatuses include a modulated data transmitting and receiving unit having a connector for coupling the unit to a communications loop, circuitry to transmit and receive a modulated data signal in a frequency range above voiceband, and circuitry to detect a resume signal in the frequency range above voiceband and then to initiate a power up sequence for the transmit and receive circuitry.

Abstract: An alarm system signals an attempt at intrusion through an opening framed to receive first and second panel members movable between opening and closing positions, as specifically shown in the form of a sliding glass door and screen door combination. An electrical switch mounted upon one panel has an element responsive to a magnetic field for developing a signal. A magnet mounted upon the other panel is productive of a magnetic field that interacts with the element of the switch upon movement of both the first and second panels to their closed positions. A signaling device coupled to the switch yields an alarm indication upon the beginning of the movement of either one of the panel members away from its closed position.