Abstract: An apparatus and method for detecting telephony signaling states, comprises an analog to digital converter and a microcomputer with associated firmware for controlling the operation of the microcomputer. The analog to digital converter digitizes incoming analog voltages containing telephony signaling state information and presents the digitized data samples for operation by the microcomputer. The microcomputer performs various digital filtering and analysis of the digital data samples in order to determine the signaling states represented by such digital data samples, and upon detection of the signaling states, outputs information indicative of such detected states. The present invention also incorporates use of such a detection circuit within line cards used to interface telephone subscriber lines with the central office terminal. The present invention further encompasses the methodology of performing such digital data sampling and analysis so as to determine telephony signaling states.
December 15, 1989
Date of Patent:
April 28, 1992
Alcatel NA, Inc., Network Systems Corp.
Eric D. Bomgardner, Randall J. Eisenach
Abstract: A telephone line interface circuit for connecting telephone equipment provided with internal speech lines having predetermined DC impedance to external telephone lines, comprising a rectifying circuit connected with the telephone lines for rectifying the DC voltage coming from the telephone lines; a dial pulse sending circuit which makes connection and disconnection between the output terminals of the rectifying circuit and the internal speech lines for sending dial pulses to the telephone lines; and a polarity inversion detecting circuit which discriminates th evoltage relationship between the telephone lines and the internal speech lines for detecting the polarity inversion of the DC voltage coming from the telephone lines.
Abstract: Facsimile equipment includes an image scanner for reading image information from an transmit original, a coder for coding the image signal to produce image data, a modulator/demodulator coupled to the coder and to a line via a network control unit, a decoder for decoding image data transmitted over the line to reproduce an image signal, a printer for printing an image on a recording paper in response to the reproduced image signal, and a dialer coupled to the network control unit for producing dial pulses corresponding to a dialing number. The facsimile equipment further includes a keyboard, a memory, and a card reader. The keyboard includes ten keys for entering dial numbers for usual dialing operation and memory keys for reading dial numbers stored in the memory for dialing by a single key operation. The memory stores dial numbers in the form of a table accessed by the types of the card and the memory key.
September 19, 1989
Date of Patent:
March 24, 1992
Kabushiki Kaisha Toshiba
Akihiko Shigami, Toshifumi Yamamoto, Shuji Yoshida
Abstract: The connection circuit comprises a first differential amplifier circuit having its output connected to a first symmetrical amplifier circuit, a second differential amplifier circuit having its output connected to a second symmetrical amplifier circuit, a power supply and filter circuit for delivering power via a power supply series connection to the two symmetrical amplifier circuits, a balancing circuit, and a loop state signaling circuit. The two differential amplifier circuits are connected firstly to the output of a receive circuit and secondly to ground, and each wire of the line is connected directly via a respective resistor to a transmit circuit. Each symmetrical amplifier circuit is connected to one of the line wires via a contact of a ringing relay and a resistor connected in series. The power supply series connection includes a power supply transistor controlled by a signal indicative of the line being looped.
Abstract: A mobile telephone apparatus having a conventional key pad, memory for storing telephone numbers at locations identifiable by certain digits and a processor for controlling the auto dialing of telephone numbers in response to a key pad input of the respective digits. The apparatus further includes a capability of receiving telephone numbers transmitted from a remote operator and storing the numbers at memory location that may be auto dialed.
Abstract: In a radio paging communication system, an exclusive input device such as a personal computer capable of inputting alpha-numeric code data and a normal key telephone are included for inputting message data to an alpha-numeric paging receiver. The alpha-numeric paging receiver includes a circuit for detecting a specific code in the message data. In order to input message data from the key telephone set, the specific code is input prior to input of the message data. The paging receiver displays data following the specific code as numeric code data.
Abstract: A terminal repeater placed in at least one communication line connecting an exchange and at least one terminal device, comprising a DC cut-off circuit providing continuous paths for AC signals flowing through the lines while providing discontinuous paths for DC signals flowing through the communication line, a DC power supply circuit generating a DC power used in place of a DC power supplied through communication line from the exchange, and supplying the generated DC power to terminal device, a DC loop signal detecting circuit comparing a threshold level with a level of a DC loop signal as is transmitted from the terminal device to the exchange, and generating a signal corresponding to the DC loop signal, and a pseudo-DC loop signal transmitting circuit, when the DC loop signal detecting circuit generates a signal, the pseudo-DC loop signal transmitting circuit controlling a C state of the communication line in accordance with the signal generated by the DC loop signal detecting circuit, thereby to transmit a
Abstract: Filter circuitry for filtering noise from a pair of telephone conductors connected to a modem or a facsimile transmission unit includes a capacitor in series with a fixed resistor. A vaariable resistor is connected in series with the capacitor and the fixed resistor. The capacitor is non-polarized. A switch is connected in series with the filter elements for selectively connecting and disconnecting the filter from the telephone conductors.
Abstract: There is disclosed a tone type recognition method capable of recognizing a call progress state of a central office line switching system by using a tone detector. The method enables the system to correctly recognize the type of call progress tone, regardless of its frequency, by conducting periodic detection of characteristics of cadence classified by tone-type.
Abstract: A circuit to improve noise mitigation and mode switching in telephony, wherein the noise-floor level is continuously estimated by comparing its stored current value to the signal level value and substituting the latter for the former if it is less than the former.
December 27, 1989
Date of Patent:
October 15, 1991
Edward C. Carew, Roland T. Lockhart, Sean G. Brophy
Abstract: A circuit for maintaining hybrid cancellation of signals carried by a signal bus of a communication system, in response to variations in the number of hybrid circuits connected to the bus. One or more microprocessor control switches are utilized for selectively connecting one or more balancing load impedances to the bus in response to variations in the number of hybrid circuits connected thereto, such that a constant total load impedance is maintained on the bus. Also, circuitry is associated with each of the hybrid circuits for effecting hybrid cancellation of signals on the bus relative to the constant total load impedance. The circuit is of simple design and construction, occupying every little circuit board area and being of very low cost.
Abstract: Alternating current signals are differentially coupled between a two wire communications line and a telecommunications facility by a line interface circuit. The line interface circuit differentially drives signals destined for the two wire communications line, with a predetermined source impedance, via tip and ring amplifiers and tip and ring feed resistors. An amplifier circuit differentially receives signal voltages being developed by currents traversing the tip and ring feed resistors, and detects signals destined for the telecommunications facility by subtracting a representation of the signals destined for the two wire communications from a representation of the differentially received signals.
Abstract: A digital decimation filter for receiving a stream of input digital samples at an input sample rate, and for delivering a corresponding stream of output digital samples at a different output sample rate stores a plurality of input digital samples, derives samples of the output stream from the stored input digital samples, and makes an output sample available for inclusion in the output stream at all times, whereby the output sample may be delivered with a selectable phase.
Abstract: A Data Communication Device permits extended range RS-232 communications between two devices by utilizing a current loop between the remote device and the Data Communication Device. The Data Communication Device may be used for any mix of signal or control lines specified for RS-232 and will support multiple remote devices in a broadcast mode or half duplex polled mode. Only a single Data Communication Device per remote communications circuit is required.
Abstract: There is disclosed a resetting circuit of a key telephone system (KTS) capable of preventing data error caused by unstable power supply and instantaneous power-off of a key system unit (KSU), by adjusting a DC voltage of the key telehpone system, said DC voltage is applied to a reset terminal of a microprocessor in the key telephone system. The invention includes a power supply for supplying power to the KSU and KTS, a microprocessor for controlling the overall operation of the KTS, a first detecting means for detecting the voltage change of a first voltage Vcc1, and a second detecting means for detecting the voltage change of a second voltage Vcc2.
Abstract: A dialer circuit equipped with built-in dialer memories for auto-redial or abbreviated-dial telephone communication and operable to send out a DTMF signal or a pulse signal to a telephone circuit based on a key input signal. A battery voltage is supplied to the dialer memories from a back-up battery, while a supply voltage is supplied to the other function circuits from a telephone circuit line. A voltage level converter means is located between the dialer memories and the other function circuits and eliminates production of through current resulting from the difference between the back-up battery voltage and the line voltage.
Abstract: The whole or part of a waveform is cancelled by a circuit comprising a nonrecursive filter and a recursive filter. The nonrecursive filter has a plurality of first multipliers having first tap weights for modifying symbols successively shifted along a shift register. The recursive filter is connected in a series circuit to the shift register and has a second tap weight for recursively modifying the output of the shift register. The recursively modified symbol is modified by a second multiplier having a third tap weight and combined in an adder with the symbols modified by the first tap weights to produce a replica of an undesired waveform. The replica is destructively combined in a subtractor with an incoming symbol having an undesired waveform. The output of subtractor is utilized to derive the tap weights to adaptively control the inputs to the adder.
Abstract: A method and apparatus for generating dual tone multiple frequency signals employing a low frequency quartz oscillator, wherein a phase accumulation dual tone multiple frequency generator is comprised of a low frequency quartz oscillator. Two phase selectors are connected to produce digital phase signals in response to a signal input. Two phase accumulators, each composed of an adder and a register, are connected to accumulate the phase signals. Two ROM based sine wave tables are addressed by the outputs of the accumulators. An adder adds the outputs of the ROMs, and a D/A converter produces an analog output from the output of the adder.
April 4, 1989
Date of Patent:
July 23, 1991
Industrial Technology Research Institute
Abstract: A telephone line switch actuating mechanism includes two identical parts, each having a portion which makes up a plunger, while the remaining portion is pivotally mounted for enabling the two parts to be assembled in an opposing relationship to each other into a mechanism such that depression of either plunger activates the other plunger and the telephone line switch.
Abstract: A dialer circuit comprising a microcomputer for controlling the dialing of a telephone. This dialer circuit is capable of storing a telephone number and transmitting a signal concerning this telephone number to a telephone circuit according to a given command. The dialer circuit is equipped with a means for detecting the ON state or the OFF state of a hook switch; upon detection of the state of the hook switch, the dialer circuit performs a resetting of the entire system except a memory in which the telephone number is stored. The result is that when operating the hook switch, it is possible to automatically reset only the system, thus effectively preventing any reckless driving of the system.