Abstract: A subscriber data carrier system for simultaneously carrying both base band telephone signals and full duplex digital data transmissions on a single pair of nonloaded telephone wires is disclosed. That is, the system provides for simultaneous conventional telephone signaling and audio communication and full duplex digital data communication between a pair of subscribers, each connected to the same main distribution frame of a central office by a single pair of nonloaded telephone wires. The system includes a modem (21) located at each subscriber's premises. The modems are connected to the subscriber's telephone (23) and digital data terminal (25). The modems include data transmitters (47) and receivers (49) that convert digital data from binary form into FSK form for transmission and from FSK form into binary form upon reception.

Abstract: Simultaneous conventional telephone signaling and audio communication, plus digital data transmission, on nonloaded telephone wires is disclosed. Modems (21) connect a telephone (23) and a digital data terminal (25) to one end of the telephone wires. A data transmitter (59) in each modem (21) converts digital data from binary to FSK form and a receiver (57) converts digital data from FSK to binary form. Each transmitter includes a frequency synthesizer that produces one of two FSK signals (F1, F2) depending upon the binary nature (0 or 1) of a particular data bit; and, the receivers include frequency detectors that detect two other FSK signals (F3, F4) and produce a corresponding binary data bit (0 or 1). Voice filters (51) prevent the FSK data signals from reaching the telephones and spurious telephone high frequency signals from reaching the telephone wires.

Abstract: An electronic lock system including a key coder, a key or set of keys and a lock or set of locks. The key coder provides an operator-selectable key code having a new code portion and current code portion to each key. The key receives the selected key code from the key coder and retains it for use with the lock or set of locks, one at a time. When the lock receives the key code from the key, a comparison is made in the lock between the current code portion of the key code and a lock code contained within a memory in the lock. If the current code portion of the key code compares the lock code, the lock is actuated and the lock code in the memory is replaced by the new code portion of the key code. If the new code portion of the key code is identical to the current code portion of the key code, the key will actuate the lock and will continue to do so until the lock is once actuated by a key having a different new code portion of the key code.

Abstract: A solid state electronic battery charger which is electromagnetically coupled to one or more batteries. A charging circuit energizes a drive winding to produce an alternating field received by an associated coupler and operative to convey charging current to a battery connected thereto. A sense winding monitors the level of the alternating field to derive a signal representative of the battery charge level and which causes a tapered charge to be supplied to the battery and an indication of a sensed fully charged state. A proximity sensor can be provided to denote the presence of a coupled battery and by which charging operation is commenced.

Abstract: An inductively coupled electronic lock system wherein a key unit receives binary multiple bit data and generates a binary frequency modulated carrier which is input to a transmitter inductor. A lock unit of the system has an inductive pick-up which compares the received sequence of binary signals with a predetermined sequence of binary signals so that upon a proper correspondence a motor opens the lock.