Abstract: A transmitting receiving circuit having two different blocks, one for transmitting, and one for receiving, the transmitting block relying on an inverter and a differential transmitter, while the receiving block has a differential receiver, four optocouplers, two inverters, a voltage regulator and two resistors, the galvanic discoupling being carried out between the parts corresponding to the transmission and reception by telefeeding the differential receiver from the board where the signal is transmitted, the optocouplers separating the receiving block parts fed from the board where the transmitting-receiving circuit is installed, from the parts fed from the module transmitting the signal, the output thereof being optically disconnected from the distant end.

Abstract: A coin return mechanism for public telephones has a coin box 1 with an access door 13 and a cam 15. The access door 13 and cam 15 are mounted on a shaft 14 that turns when door 13 is pushed, and return to the their resting position when the door is no longer pushed. A pusher 3 includes a square section rod 35 having an angular deformation of 70.degree. at one end, and having a recess for housing a wheel 33 that rotates atop cam 15. The other end of the square section rod 35 has a drilled hole for receiving a shaft that supports a forked prismatic part 34 that turns about the shaft. The two arms of the forked part 34 and the rod 35 have drilled holes through which the shaft passes. A spring 36 situated on the shaft is fastened to the an end of the forked prismatic part 34 and to the rod 35. When the access door 13 is opened, cam 15 moves and causes pusher 3 to move upward and cause a cylindrical pin 67 in a coin inserting mechanism 4 to block a coin insertion slot 46.

Abstract: An interface scanning circuit includes a current source at the input to a multiplexer. The current source includes a transistor disposed between two resistors, the second one of which limits reverse current. Also provided are an attenuating network including two resistors, and a low pass filter capacitor associated with the attenuating network.

Abstract: A junction and modular optical sharing terminal assembly incorporates a vertically-extending frame having a plurality of frame plates vertically mounted thereon and a plurality of horizontally-extending, telescopic tray guides mounted on the frame plates and which are movable between a retracted position and a horizontally-extended position. Horizontal tray modules rest on the tray guides and are movable between a retracted position and a horizontally-extended position. The tray modules include warehousing, junction, and connector trays, each having identical perimeters and terminating at their sides with identical anchoring bands which removably rest on the tray guides, and each including a molded part at its front edge. A resilient trigger band is mounted on each of the anchoring bands, and interacts with the molded part and the tray guides to lock the tray modules in their extended and retracted positions. A housing encloses the frame, the frame plates, the tray guides, and the tray modules.

Abstract: An electrooptical line module for transmitting in Level-1 Synchronous Digital Hierarchy with a synchronizing unit that includes a single line module on a single printed circuit and components capable of performing transmission, reception, recovery and clock and alarm synchronization functions. The line module includes a subunit capable of converting an input electrical signal received by the module into an optical signal to be transmitted via fiber optics.

Abstract: The present invention provides a telecommunications packet switching system including a hardware portion and a software portion forming an advanced multiprocessing, multiprocessor system (including multiple processors, capable of running more than one process at a time). The hardware and software structures are fully distributed and fault-tolerant, providing a flexible configuration and remote management through the network itself, managing the switching and transmission of messages split into packets, including use of different specific protocols. The system can be connected to a variety of different networks, allowing a large concentration of low speed lines. A control station executes operational functions, and a terminal allows interaction with the system. A DC/DC converter is provided at each element in the processing unit.

Abstract: Maintenance unit for modular public telephone, the unit being made up based on a microprocessor, a block for communication with the modular telephone, a rotating switch to take measurements and a condenser charger for the modular public telephone, with a rapid condenser charger to feed the modular telephone that will load the logic and the activators, allowing the unit to communicate through any telephone situated on a line protected by a validation and identification unit, and carrying out the same through the selection of the identification number on turning switches. The unit also has circuit blocks to measure feed condenser voltage, line current, alternative voltage with respect to grounding and the state of the battery.

Abstract: Maintenance terminal of a validation and identification unit defined as a tool designed to accomplish two functions allowing the local initialization of the validation and identification unit or of the adaptation unit of public modular telephones, so being not necessary for the operation system of modular telephones to call these, allowing extensive diagnosis and failure identification, also in a local mode, whenever the central processing unit be operative through the use of an interactive man-machine language.