Abstract: An intercom system for use with a plurality of telephones on a single extension includes a single master station and a plurality of slave stations. The master station is connected so as to interrupt the telephone line pair to and from a central exchange. Each slave station is preferably associated with a handset that is on the extension. When the extension is not being used for intercom service or for an outside call, any telephone handset on the extension that has a keypad can initiate a signal that is received and decoded in the master unit. When the master station receives such a signal, it disconnects the line to the telephone exchange from the extension and connects the telephone exchange to a circuit that detects incoming calls so that they can be signaled to users. The master station also sends a signal to each slave station that enables the intercom function.

Abstract: A modem for connecting data terminal equipment (DTE) to a remote DTE via a the general switched telephone network or leased lines at data rates of 300, 1200 and 2400 bps using standard modulation techniques, and additionally providing virtual full duplex transmission capability at 9600 bps using trellis code modulation (TCM). The high-speed 9600 bps path is implemented by asymmetrical frequency division of the available bandwidth into a high speed, wideband forward channel (9600 bps) and a low speed, narrowband backchannel (300 bps). The high speed transmitting channel is assigned to that modem having the greatest data demand and the direction is dynamically reversed whenever the amount of data awaiting transmission over the low speed channel exceeds a predetermined maximum backlog, provided that a direction reversal has not taken place for at least a specified minimum interval during which use of the forward channel is guaranteed.

Abstract: In an audiovisual communication, a first high fram rate video signal is derived from a motion image and converted to a low fram rate low resolution multiframe signal. A second high frame rate video signal is derived from an still image and converted to a single frame high resolution signal. Because of the low frame rates, the frequencies of the low and high resolution signals are within the range of frequencies of a telephone exchange line. A switching matrix is provided to sequentially couple both the low and high resolution signals to a transmission line in response to a mode select signal. The single frame high resolution signal is stored into a memory at the receiving end and repeatedly retrieved out of the memory into a display through the switching matrix.

Abstract: A communication terminal apparatus having a handset which includes a transmitter, a receiver and a hook switch. The handset is connected to the main body through a modular jack having four pins. The handset includes a bypass circuit for flowing a d.c. component therethrough by bypassing the transmitter or receiver and a capacitor, which is connected in parallel with the bypass circuit and in series with the transmitter or receiver, for cutting a d.c. component. Thus, the status information of the hook switch is applied to a signal line of the transmitter or receiver in a d.c. format superimposingly.

Abstract: An electronic remote data recorder records pulses representing usage of a commodity such as, for example, water, gas or electricity from a plurality of consumers. The data from each consumer is stored in a respective data storage device. Each data storage device is associated with an interval data directory which stores the times at which significant events, affecting the data in the data storage device occurred. Thus, the data in the data storage device is compact, without requiring a contemporaneous time code for each data item. Data integrity is retained over a period of power outage in a non-volatile storage device. Initial, post-installation programming is enabled by comparing the data pattern in the non-volatile storage device with a predefined data pattern that is expected to exist once the apparatus has been programmed. A write-protect switch prevents programming during an incoming call after the initial programming.

Abstract: Telephone terminal equipment has circuitry for preventing malicious and nuisance transmission of information by detecting during reception of an incoming call whether or not any person is present around the equipment. Information from a calling party is received without any limit when no person is around the equipment. An owner can remotely operate the equipment to set the limited number of paper or to release the limit for receiving information as he desires.

Abstract: A fail safe voice system and method for digital telephone networks. The system provides for operation of voice telephone equipment at a customer location when a fault occurs at the customer location. The system has a central office with an analog line termination/digital transceiver connected to subscriber loop lines. The customer location has a digital transceiver/analog station set interface connected to the subscriber loop lines and to the voice telephone equipment. In response to a fault at the customer location the voice telephone equipment is connected directly to the subscriber loop lines thereby eliminating the digital transceiver/analog station set interface.

Abstract: An optical hookswitch assembly useable on a telephone set as an optical communications port is disclosed. The hookswitch assembly is comprised of light emitting and detecting diodes so disposed in the telephone so as to detect the presence of a handset. A processor connectable to the telephone circuitry and the light emitting and detecting diodes is provided such that the telephone circuitry is activated by the processor when the light emitting and detecting diodes fail to detect the presence of a handset. The light emitting and detecting diodes are useable as an optical communciations port for accessing the processor by allowing an external computer to communicate with the processor via an optical coupler.