Abstract: An electronic hold circuit for a telephone. A single sensing and latching module is connected across the telephone lines, and is adapted to sense the voltage present on the telephone lines to distinguish between on-hook, off-hook and hold conditions. The hold feature is engagable by one or more hold signaling modules disposed, for example, near each telephone and extension telephone in the system. Each hold signaling module comprises a switch associated with a level establishing device, for establishing a voltage on the telephone lines at a level intermediate the relatively high on-hook voltage and the relatively low off-hook voltage. The sensing and latching module responds to this intermediate level by latching the telephone lines at a voltage sufficiently low to maintain the connection with the called or calling party.

Abstract: An automatic dial system for a subscriber telephone utilizes a keyboard array to enter coded information into an integrated circuit digit processor. The digit processor includes a programmed ROM for storing an instruction set to control the operation of the dial system, an arithmetic/logic unit for performing arithmetic and logic operations on data according to said instruction set, and a first read/write RAM for storing the data being processed. A second integrated circuit RAM, which is selectively connected to the output of the digit processor, is provided for the storage and retrieval of changeable groups of selected telephone numbers.A pulse or tone generator is also selectively connected at the output of the digit processor for the selective transmission of pulse or tone signals over the telephone lines according to the stored instruction set and coded information derived from the keyboard.

Abstract: A microphone assembly or apparatus comprises a perforated capsule having a microphone unit supported therein and a tubular projection communicating with the interior of the capsule. The projection is arranged to be inserted into the auditory canal of a human or dummy head. The microphone unit is located near the opening of the auditory canal.

Abstract: A telephone intercommunication system where a plurality of stations have access to a plurality of lines. Each station has a pushbutton type keyset which is connectible to integrated circuits associated with each line and are utilized and generate signals for controlling central office switching equipment.

Abstract: A communication system includes a mobile station, a plurality of base stations and a central terminal. Each base station converts RF signals from the mobile station to AF signals. The AF signals are carried over a balanced line to the central terminal. Each base station generates a DC voltage signal whose level is representative of the level of its received RF signal. The central terminal includes means to monitor DC current levels, from each base station, on the balanced line and select that base station producing the highest DC current.The unique interface circuit senses the base station generated DC voltage, which is referenced to a fixed ground potential, and produces a corresponding current which is referenced to a floating ground potential. This current is then coupled to the balanced line for transmission to the central terminal. The interface circuitry includes a DC to AC converter which converts the DC signal voltage to an AC signal.

Abstract: The present invention relates to a device which is to be used in conjunction with key telephone systems, as for example, intercom systems. More particularly, the invention consists of a device for decoding the pulse output from rotary dial telephones, indicating which digit has been dialed and selectively signalling the called party. Special features include acceptance of a wide range of pulse speeds and ratios with decoding immunity to the initial hookswitch closure and the last opening. The latter permits the digit "1" to be used, providing for an additional signal function. A decoding matrix operates a relay tree with provisions for either single or two-digit codes. The device is intended for use in key telephone systems which include rotary dial telephones.

Abstract: A switching arrangement for a telecommunication system is described. A switching network having a plurality of switching matrices arranged in several stages are used, and a reverse trunking connecting arrangement is used. The switching network is divided into similarly constructed switching networks of two types. The first type switching network has only subscriber lines connected to its inputs. The second type switching network has connected to its inlets interexchange lines and switching equipment required for each connection. Special sub-control units are separately coupled to each switching network section. The switching network sections are each connected in parallel, at their outputs, to multiple lines.

Abstract: Disclosed is a method and apparatus for detecting the presence of signals, particularly touch-tone signals, of characteristic complex waveforms by comparing unknown signals with pre-specified digital formats or "masks" representative of such waveforms. The apparatus includes digital circuitry defining the masks and digital circuitry for counting the number of times during a prescribed time period there is a correlation between the digital format of the unknown signals and the masks.

Abstract: An additional concentrator is provided in a Traffic Service Position System (TSPS) similar to that disclosed in A. E. Joel, Jr. Pat. No. 3,731,000, issued May 1, 1973, to facilitate the handling of operator assistance telephone calls requiring routing back to originating offices. More specifically, on the toll office side of this additional concentrator in addition to the normal TSPS remote toll trunks, "loopback" trunks are provided for establishing connections through this concentrator directly back to a plurality of "local" offices served by the concentrator. Operator assistance calls in which only a single digit (normally 0) is dialed are connected to these loopback trunks with the expectation that the call will be completed back to the originating or associated office.

Abstract: A communication system is disclosed for providing itemized telephone subscriber billing of special assistance calls. A local office not equipped with automatic message accounting facilities is interconnected via a trunk circuit to another exchange having such facilities and thence to a special assistance bureau. The trunk circuit is accessible by the local office for both message rate billed and special assistance classes of traffic. On each call therethrough, the trunk circuit translates subscriber dialed digits for selecting the automatic accounting facilities or message rate billing apparatus in the local office in accordance with whether the call is of a special assistance or local toll call class as defined by the digits.

Abstract: An improved artificial reverberation system utilizing a unitary electro-acousto-electrical transducer of the electro-dynamic type in combination with means for eliminating the driving signal from the delayed output signal, such means including out-of-phase-signal cancellation circuits or time multiplexing circuits coupled to or integral with the unitary transducer achieves a high order of discrimination between driving and reflected signals in the system, thus permitting the use of a single transducer for both injecting signals and extracting reverberation signals.

Abstract: An arrangement and method for providing a dial pulse muting function to prevent the sender outpulsing from being heard is to disable the sampling of the transmit to the network side of the trunk circuit which is connected through the time switch and to the receiver from the network side of the line circuit. This function takes place in the trunk circuit, rather than the line circuit, so that less equipment is required. The function, furthermore, is provided through the use of integrated circuit chips as opposed to relays so that less space is required and the arrangement is far more reliable.

Abstract: An inertial-reaction microphone transducer mounting supported on the wearer's head away from the mouth for transmitting speech to the exclusion of ambient. A compliant, radial array of elastomer supporting material presses the transducer gently to the head. The transducer and supporting array may be mounted in a cup covering one ear, or it may be mounted in a capsule having an acoustical labyrinth frequency-selective vent for the neutralization of noise.

Abstract: The headphone preferably comprises a toroidal seal ring which rests against or surrounds the user's ear and is constituted of a soft, yielding, and preferably elastic material. The seal ring, with the headphone positioned on the head of a user, forms a coupling space between an active diaphragm, actuated by an electroacoustic transducer, and the auditory canal of the user's ear. This coupling space is substantially sealed from the exterior of the headphone, and is formed with at least one opening and preferably several openings each receiving a respective passive oscillatory diaphragm having a definite self-resonance. Each passive diaphragm is associated with a sound path leading therefrom to the open air, to the back side of the active transducer diaphragm, or to acoustically effective cavities. Respective acoustic frictional resistances are associated with each passive diaphragm. The arrangement of the passive diaphragms relative to the active transducer diaphragm may take various forms.

Abstract: An arrangement for headphones for converting frequency modulated audio oscillations into amplitude modulated oscillations, and particularly for rendering audible the vibrato of electronic musical instruments, such as electronic organs, includes a housing having an electroacoustic transducer therein with a diaphragm having a smooth frequency response zone which is connected to at least one mechanical transit-time member having a transit time from one end to the other not greater than 20 ms. The transit-time member is advantageously a helical spring which extends axially through the electroacoustic transducer or through a central ferromagnetic core thereof. The portion of the spring within the core is advantageously made of a thicker wire and of a smaller diameter than the remaining core so that it does not contact the walls thereof.

Abstract: An echo controller comprises a parallel circuit of an echo suppressor and a self-adaptive echo canceller near an echo path of a long-distance telephone network. The echo controller further comprises a mode switch responsive to levels of a received signal, an unprocessed signal, and an output signal of the echo canceller and operable during absence of double talk for suspending operation of the echo canceller and putting instead the echo suppressor into operation only when characteristics of the echo path and operation of the echo canceller are objectionable.

Abstract: A trunk adapter is associated with a common control private automatic branch exchange telephone system for interfacing the system with a central office. Four different types of adapters are associated with the system to effect a ring-down incoming, loop start outgoing trunk connection, a ground start type trunk connection, a two-way dial-to-dial trunk connection, and a two-way E and M signalling interface. To provide a buffer between the ring and tip circuits the adapters employ optical coupler circuits. The adapters are controlled by the common control on a time shared basis and operate independently of the state of the sleeve lead.

Abstract: A set of components is disclosed containing various microphones, a microphone amplifier, and an impedance converter, all arranged to be connected together in different combinations, with electrical contact automatically made between them.

Abstract: In a loudspeaking telephone arrangement using voice switching a closed-loop circuit is used to apply an averaged rectified ambient-noise signal to the comparator from one or both channels to enable proper voice switching regardless of ambient noise levels or line length.

Abstract: A single channel carrier system for telephone service is disclosed including a remote terminal having a ringing generator included therein for generating ringing signals to operate the ringers of remote subscribers. The ringing generator is a dc-to-dc converter for stepping up a battery voltage to ringing voltage level that is interrupted at a 20 Hz rate.The generation of ringing signals is controlled by a carrier signal interrupted at a ringing rate. Detection of the ringing signals on the carrier utilizes a delay circuit to prevent response to inadvertent signals as well as delay hysteresis to ensure the bridging of detection from one 20 Hz cycle to the next. The ringing generator must also be regulated, both in current and in voltage, to prevent danger to personnel, damage to equipment, and excessive power consumption.