Abstract: A system for storing dial data from a teletypewriter subscriber is arranged to be stored at the subscriber station until a new number is dialed by the subscriber. The system is arranged to handle both dial-pulse forms of dialing information as well as the baudot code as used for teleprinters. Repeated spilling-out of stored dialed data is accomplished by the depression of a single switch or button provided on the teleprinter apparatus such as a touch-pad. This system is arranged to be compatible with existing teletypewriter switching exchanges of the computer or conventional automatic switch system type.

Abstract: An AC burst having a length depending upon the response chosen by the participant is put on a telephone line regardless of the operating state thereof, at a frequency outside of the telephone band. At the central telephone station the bursts are decoded and response signals corresponding to each answer are summed. The resulting totals are transmitted via private lines to a central computing station where the totals corresponding to a given answer are again added. For television channel polling, a control signal signifying an operative television receiver is also put on the telephone line and, at the central computing station computer circuits compute the percentage of television sets tuned to any given channel.

Abstract: A telecommunications system using TDM principles for signalling and speech path usage plus PAM principles for speech transmission. Each function circuit such as a trunk, link or register, etc. is allocated a basic time slot or channel for initiation of its function when indicated. The active period of each function circuit is continued during the period of three succeeding time slots. In this way, up to four function circuits or channel units may be active during a finite period of time.In the system, a line is scanned at the end of each complete scan of all channels, thereby lessening the complexity of associating a line and a function circuit. The system shown uses the dual highway principle for its speech path and provision is made in each line circuit for switching onto both highways.

Abstract: Control pulses of highest positive level, clock pulses of negative middle level and reset pulses of lowest negative level are transmitted through one or more transmission lines. Separation of those pulses in the receiver is performed by means of simple rectifiers connected to the transmission lines. In both transmitter and receiver, binary counters and decimal decoders are utilized for repeatedly producing channel pulse sequences.

Abstract: An acoustic power system includes a speaker which generates acoustic energy in response to electrical driving signals. Electrical representations of the acoustic energy generated by the speaker are effectively subtracted from electrical input signals having a preselected frequency response to produce electrical error signals. The error signals are amplified to produce the electrical driving signals which operate the speaker. In the preferred embodiment, the electrical representations of the acoustic energy generated by the speaker are produced by detecting a portion of the impedance produced across the speaker voice coil.

Abstract: Apparatus is described for detecting undesirable duplications in connections in time division multiplex telecommunication systems, e.g., pulse code modulated telephone systems. The multiplex trunks are coupled through time coupling stages which may take the form of storages allocated to individual trunks, and the trunks are connectable in pairs, by means of cross-point switches, over pairs of time multiplex channels to outgoing time division multiplex trunks. A parity generator and an OR gate are inserted between the trunk-challel side terminals of the crosspoint switches extending from the incoming trunk in question to the same trunk and the trunk in question. An output of the parity generator is coupled, along with an output of the OR gate, to an exclusive OR gate, which produces an output signal responsive to a dissimilarity in inputs. The appearance of the latter output signal indicates the existence of a double connection.

Abstract: A loud speaker of the oscillating coil type including a voice coil associated with a loud speaker membrane and a magnetic circuit having an annular air gap in which the coil is located in such a manner that in its neutral, non-energized condition the coil projects axially from the air gap substantially uniformly to both sides thereof so as to be able to oscillate substantially symmetrically about the middle plane of the air gap, a cylindric element of an electrically conducting material being rigidly associated with the magnetic circuit concentrically with the coil and extending into the air gap from one side thereof, characterised in that the cylindric element is extended so as to additionally project outwardly from the air gap to the other side thereof. It is obtained hereby that the voice coil is inductively short circuited in all working positions thereof, whereby it responds rapidly to changes of the input voltage and thus causes the sound to be reproduced with a minimum of distortion.

Abstract: An automatic telecommunication switching system is disclosed for switching TDM speech signals and data signals between calling and called parties. The system includes auxiliary circuits. Such circuits may include a monitor or comparator to detect the presence of a particular code. They may include a code converter for receiving a code of one variety and transmitting one of another variety or for changing the speed between reception and transmission.

Abstract: The present invention relates to a transit exchange for the transmission of asynchronous data signals having an unknown character structure and data rate with the aid of a control equipment including a processor and a sampling device which is common to a number of sending terminal equipments and which works on the time multiplex principle. The data signals received on each of a number of incoming lines are sampled at a frequency so selected in relation to the data rate, expressed in unit elements per second, that the number of sampling pulses per unit element of the data signals is not less than the reciprocal value of the permitted relative time distortion.