Abstract: A system comprising customer premises equipment including a reverse power supply unit and an access node to which the customer premises equipment is connected for permitting telephony devices connected to the customer premises equipment to make and receive telephone calls via the customer premises equipment and the access node. The reverse power supply unit is suitable for supplying electrical power from the customer's premises to an access node via a twisted copper pair, the reverse power supply unit including a power consumption signature detector operable to detect if the power drawn from the reverse power supply unit corresponds to a signature power consumption pattern indicative of a telephony device being in or transitioning into an off-hook state when connected directly to the reverse power supply unit and not being connected via a current limiting interface.

Abstract: A method for retrofitting a vending machine with a video communications device includes securing a video communications device with a mounting feature of the video communications device removably coupled with a mounting location on a vending machine. The video communications device includes a video communications module for real-time interactions with a ticket office. The video communications module includes a display, a camera, a speaker, and a microphone. The video communications device includes a video communication device communications interface. The method includes electronically coupling the video communications device with a power supply of the vending machine and communicatively coupling the video communications device with the vending machine such that functions of the vending machine are controllable using the video communications device. The method includes communicatively coupling the video communications device with the ticket office for real-time video communications with the ticket office.

Abstract: This invention provides a communication apparatus, which suppresses abrupt changes of a current and voltage generated in a communication line upon connecting an external telephone to the communication line, and a control method thereof. To accomplish this, in a communication apparatus of this invention, when an off-hook state of an external telephone is detected upon connecting the external telephone to a communication line, an SOC captures a line using a first line capture means having an impedance lower than the external telephone side, and then switches an H-relay to connect the external telephone to the communication line. Furthermore, the SOC temporarily switches a line capture state to a second line capture means having an impedance higher than the first line capture means after the H-relay is switched and before the line is released.

Abstract: The invention relates to methods for testing analog telephone line equipment including, in particular to detect faults in their hybrid resistor arrays. It consists in isolating the equipment from the telephone line and then applying the normal ringing signal to it. If the resistor array is defective, the output logic signal of the off-hook/on-hook detector circuit comprises a succession of 0 and 1 at the frequency of the ringing signal, which indicates the fault. This makes it possible to eliminate the equipment test relay usually employed.

Abstract: A termination device for a telephone line of a wire based telephone system, said termination device (30) comprising: a high pass filter (39) for separating signals within a frequency band used by a high-speed modem (13) for data transmission; and impedance means (53) connected to the high-pass filter (39), wherein said impedance means (53) has an impedance which matches the impedance of the telephone line in the frequency band used by the high-speed modem (13).

Abstract: A filter (45) is passive and has a complex impedance which gives good impedance matching to the complex impedance of a transmission line. Because the filter is passive, it does not need to be powered and can thus be placed in locations that lack a power supply. The filter can also function in the event of a power failure. Because the filter has an impedance which can be well matched to the complex impedance of a transmission line, problems relating to echo and side tones can be minimized.

Abstract: In a transmission line, nonlinear impairments resulting from imperfect splices are mitigated by providing a bias current that shifts the operating points of these impairments resulting in improved stability, conductivity and linearity.

Abstract: An interface circuit that interconnects a terminal device at an extension station with the adjunct port circuit of a telephone of a business communications system (BCS), such as a digital PBX. The interface circuit enables a call diverted to a BCS telephone to be answered at the extension station. The interface circuit receives a ringing control signal from the adjunct port circuit when its BCS telephone is rung on an incoming call. This causes a ringing current source in the interface to apply ringing current to the extension station simultaneously with ringing of the BCS telephone.

Abstract: A method and apparatus for an automatic ring again feature on a telephone set for a user that answers a telephone call not intended for that user is disclosed. If a user has answered an incoming telephone call not intended for that user, a “Ring Again” feature on the telephone set is activated. In response to the Ring Again feature being activated, parallel telephone sets will ring again to allow a different user to answer the call or, alternatively, another device, such as an answering device, to answer the call.

Abstract: Overhead voltage is allocated in a telecommunication system among different AC signals, such as POTS, on-hook transmission POTS, PPM and XDSL signals, communicated between a telephonic switch and a user device. The allocation is based on the available overhead voltage, the condition, such as impedance, of the line carrying communications to the user, and which of the signals are to be communicated.

Abstract: The invention herein is fallback function communications device comprised of a microprocessor, utilized to perform a predetermined operation and processing of a predetermined input signal and then output a corresponding signal, as well as a minimum of one relay circuit having an amplifier circuit and a relay. The terminal at the first side of the relay is connected to the telephone line tip/ring terminal, while the terminal at the second side of the relay is connected to the Public Services Telephone Network (PSTN) tip/ring terminal of the microprocessor. An off-hook detection circuit is connected to the PSTN tip/ring terminal and also connected to the ring detection terminal of the said microprocessor. A dummy load circuit is connected to the tip terminal and the ring terminal of the PSTN. As such, in the event of Voice Over Internet Protocol (VOIP) system failure, the present invention is capable of automatically switching to the PSTN and thereby maintain telephone system operation.

Abstract: A digital direct access arrangement (DAA) circuitry may be used to terminate the telephone connections at the user's end to provide a communication path for signals to and from the phone lines. Briefly described, a means for providing a proper hookswitch transition for a variety of international phone standards is provided. The invention may also be utilized with means for transmitting and receiving a signal across a capacitive isolation barrier. More particularly, a DAA circuitry may be utilized which satisfies many or all hookswitch transition standards without the use of additional discrete devices. The hookswitch transition standards may be satisfied by ramping down the current flowing through the hookswitch prior to transitioning the hookswitch state. In this manner the hookswitch current change as a function of time (di/dt) may be decreased. Thus, the current through the hookswitch may be actively controlled prior to switching the hookswitch from an off-hook condition to an on-hook condition.

Abstract: A circuit for closing a relay when an active AC voltage connected to one of the contacts of the relay is approximately zero volts includes a monitoring circuit that monitors the active AC voltage and outputs a phase-shifted voltage that crosses zero volts at predetermined times before the active AC voltage traverses zero volts. A pulse generating circuit initiates a pulse when the phase-shifted voltage enters a predefined voltage region and terminates the pulse when the voltage exits that region. An input signal is strobed onto the control input of the relay by the pulse so that the relay changes state coincident with the zero crossing of the active AC voltage.

Abstract: A circuit for determining connection status of a phone line shared by multiple telecommunications devices, such as modems and phones, is provided. The phone line includes respective tip and ring lines. The circuit comprises a first transistor stage coupled to receive a signal indicative of a voltage difference between the respective tip and ring lines. The first transistor stage is configured to supply an output signal having a predetermined time response. The circuit further comprises a second transistor stage coupled to the first transistor stage and configured to supply an output signal having a slow time response relative to the output signal from the first transistor stage.

Abstract: A line circuit utilizing a differential amplifier whose output is regulated to zero volts D.C. (when the subscriber's set is off-hook) by a negative feedback circuit, for controlling a voltage controlled power supply which provides a constant current feed to the subscriber's loop. The differential amplifier also transmits audio signals received from the subscriber's loop directly to a PABX via an unbalanced terminal. When the loop range exceeds a predetermined threshold, the circuit reverts to a voltage feed operation thereby allowing operation over long loop lengths and the ability to provide on-hook CLASS services.

Abstract: A comparing unit 18, when a radio unit 1 receives a radio signal, compares an ambient noise level detected by a noise sensor 17 with a preset threshold value. If the ambient noise level is smaller than the threshold value, the comparing unit 18 outputs a set value signal SH, and sets a receiving voice level set value of a receiving voice level setting unit 19 to “SMALL”, a transmitting voice level set value of a transmitting voice level setting unit 20 to “LARGE” and a calling sound level set value of a calling sound level setting unit 22 to “SMALL”, respectively.

Abstract: A flux cancelling transformer line circuit includes an AC current source that blocks AC current and passes DC current. The current source is connected between the primary and secondary windings of a transformer. Direct current flowing through the primary winding generates a magnetic flux. The current source passes the direct current to the secondary winding self-cancelling the DC flux created in the primary winding. Since DC current is coupled from the primary windings directly into the secondary windings, the same DC current flows in both windings. Thus, DC flux is precisely cancelled in the transformer. The current source includes a transistor, which is biased in a low impedance linear region by the DC signal and a capacitor that operates the transistor in a high AC impedance condition.

Abstract: In an arrangement for the connection of two or more terminals (1, 1') to one subscriber line (3) the terminals (1, 1') are connected to a chain so that the connection from the subscriber line (3) to a terminal (1) is further branched (13) to the next terminal (1'), and the arrangement according to the invention is characterized in that it comprises means (18, 20) to detect whether the terminal (1) and the next terminal (1') are in the operating state or in the idle state; a controllable switch (12, 14) for each terminal (1, 1') connected to the subscriber line (3) in order to connect the corresponding terminal (1, 1') to the subscriber line (3) and disconnect it from the line; and means (18, 20) to independently control the switch (12, 14) corresponding to each terminal (1, 1') depending on which states are detected for the terminals (1, 1'). Thus it is possible, when required, to cut off the current from the subscriber line (3) in order to disconnect the connection.

Abstract: A technique for powering telephone lines using an unbalance current source and current sink; and a technique for improving attenuation/frequency distribution and return loss (impedance matching) of transformer-coupled wire-line communications circuits by using secondary series capacitance and an AC current pump signal source; and a generation of ringing voltage as positive voltage pulses with respect to a negative power supply voltage; and a technique for removal of AC power ripple by using an active linear floating filter for the purpose of powering telephone line circuits, and a technique for injection of real time tone samples into T1 transmissions circuits by use of a T1 framer idle code register.

Abstract: A DC termination device particularly adapted for use in a device coupled to a two wire telecommunications system. The termination device controls the tip-to-ring current through the telecommunications device by means of a voltage controlled current source. The control voltage for the voltage controlled current source is provided by digital signal processing of the tip-to-ring voltage such that the tip-to-ring current is linearly proportional to the tip-to-ring voltage when the voltage is below a specified threshold level, but is maintained constant when the tip-to-ring voltage is over the threshold voltage. Preferably, the constant current is the minimum adequate current needed for operation.

Abstract: A switch hook interface circuit couples a subscriber telephone to a subscriber telephone line. This interface circuit comprises a source of an off-hook signal, having one state indicating an off-hook condition, and a second state indicating an on-hook condition. A circuit is coupled between the off-hook signal source and the subscriber telephone line which gradually increases the current drawn from the subscriber telephone line when the off-hook signal indicates an off-hook condition, and gradually decreases the current drawn from the subscriber telephone line when the off-hook signal indicates an on-hook condition.

Abstract: An apparatus for use with cellular telephone to indicate an incoming telephone call to a user includes a cellular telephone battery pack having a circuit that generates a voltage signal with a value representative of the current being drawn from the battery by the operation of the cellular telephone. A status determination circuit monitors the voltage signal and generates a powered up state signal whenever the value of the voltage signal increases from a first selected lower value to a first selected higher value for a first preselected period of time. An incoming call detection circuit whenever the powered up state signal is present and either the voltage signal is representative of a selected periodic current transient in the current being drawn by the cellular telephone for a second preselected period of time. An alarm is operative upon receipt of the alarm start signal for indicating an incoming call to a user.

Abstract: An apparatus for use with a cellular telephone to indicate an incoming telephone call to a user includes a cellular telephone battery pack has a circuit that generates a voltage signal with a value representative of the current being drawn from the battery by the operation of the cellular telephone. A status determination circuit monitors the voltage signal and generates a waiting for call state signal whenever the value of the voltage signal decreases from a first selected higher value to a first selected lower value for a first preselected period of time.

Abstract: A telephone line interface circuit with d.c. amplifiers coupled to tip and ring paths is protected against transient voltages by a crowbar-type protection device coupled via a diode bridge to the tip and ring paths, positive and negative terminals of the diode bridge being connected respectively to ground and via a diode to a negative supply voltage line for the amplifiers. The diode prevents discharge of a capacitor, coupled between the negative supply voltage line and ground, through the protection device when it conducts. A locked up state, in which the amplifiers maintain holding current to the protection device after a transient voltage, is avoided by further diodes coupled from the negative terminal of the diode bridge to inputs of the amplifters, or by controlling a current limiter to interrupt current to the capacitor when the diode is reverse biased, so that the capacitor discharges.

Abstract: A sensor circuit for telephone line (10) includes a detection coil (12a) inserted in a telephone line (14). The coil generates a magnetic flux according to a line current which flows in the telephone line. A magnetic sensor (12b) such as a Hall element generates a voltage signal in response to the magnetic flux. An output of the magnetic sensor is amplified by an amplifier (16). A calling signal detection circuit (18) which receives an output of the amplifier includes a capacitor (20) for cutting-off a direct current component included in the amplified output. An alternating current component is inputted to a (-) input of a hysteresis comparing circuit (22) which receives a reference voltage (Vref1) at a (+) input thereof. Therefore, the alternating current component is converted into a pulse signal which is then withdrawn at an output terminal (34) as a calling signal for ringing a bell of a telephone set.

Abstract: There is disclosed a control circuit for switching between a facsimile unit and an automatic answering telephone unit. A current detecting circuit with satisfactory linearity between the mutually insulated input and output sides is used for detecting a DC current on a communication line, indicating a communication state of the telephone unit and also for detecting an AC signal, representing a speech communication signal and used for recording an incoming message in the automatic answering telephone unit. This structure allows to insulate the recording circuit and the facsimile circuit from the communication line without a transformer, thereby reducing cost and dimension of the apparatus.

Abstract: A line feed circuit employing a low-inductance transformer, and providing a major portion of the terminating impedance as line feed resistors connected between a telephone line and the transformer primary. A low impedance output amplifier drives a low resistance transformer secondary, thus reducing the need for large transformer inductances. By connecting the line feed resistors between the transformer and the telephone line, high voltage surges are absorbed by the resistors, and thus little is dissipated in the transformer. The transformer can be made physically small, because of the reduced inductance, reduced winding insulation, and reduced power requirements. The resistance forward type of line feed circuit lends itself well to simple implementation with flux cancellation and impedance synthesis circuits.

Abstract: A sensor circuit for telephone line includes a line current detecting circuit (52, 54) which generates a detection signal in response to a line current flowing in a telephone line (20, 22). The detection signal is applied to a first amplifier (56), and the detection signal as amplified is not only further amplified by a second amplifier (57) but also applied to a tone deriving circuit (60) and a CI detecting circuit (61) via a coupling capacitor (59). The detection signal as amplified twice is applied to a comparing circuit (58) which compares the detection signal from the second amplifier with a first reference voltage (V1) and a second reference voltage (V2), so that a line current supervisory signal is outputted from the comparing circuit. The tone deriving circuit includes a band-pass filter and derives a tone signal from the detection signal from the first amplifier. The CI detecting circuit detects a CI (calling tone) on the basis of the detection signal from the first amplifier.

Abstract: A sensor circuit for telephone line includes a detection coil (52) inserted in a telephone line (22). The coil generates a magnetic flux according to a line current which flows in the telephone line. A magnetic sensor (54) such as a Hall element generates a voltage signal in response to the magnetic flux. An output of the magnetic sensor is applied to a comparing circuit (58) and a tone deriving circuit (60) via an amplifier (56). The comparing circuit includes two comparators one of which compares the voltage signal from the magnetic sensor with a first reference voltage (V1) and the other of which compares the output signal with a second reference voltage (V2), so that a line current supervisory signal is outputted from the comparing circuit. The tone deriving circuit includes a band-pass filter and derives a tone signal from the voltage signal of the magnetic sensor.

Abstract: In an on-hook transmission circuit provided in a subscriber circuit connected between a subscriber terminal and an exchange, a constant-current source unit causes a constant current to flow in first and second wires during a period in which a control signal indicating that on-hook transmission should be turned ON is being received. A loop supervisory unit detects establishment of a loop including the first and second wires and a subscriber terminal connected thereto, and generates a scan signal used for causing the constant-current source means to stop the constant current flowing in the first and second wires after detecting the establishment of the loop.

Abstract: A subscriber line interface circuit that provides regulated current to telephone subscribers in an improved manner reducing the amount of power required to operate while maintaining a constant current source. The current to the telephone subscribers flows through a switching transistor, an inductive storage element, sensing resistors and a transformer. The desired operating characteristic is obtained by cycling the switching transistor. The switching transistor is cycled on at a preset interval causing the telephone subscriber current to flow from the switching transistor. The switching transistor is cycled off in response to an increase in the telephone subscriber current as sensed by the sensing resistors thereby causing the current to flow from the inductive storage element.

Abstract: A current sensor circuit for measuring by means of a Hall element the magnitude of a magnetic flux obtained in response to an input electric current and for generating a signal corresponding to the result of measurement, wherein a Hall element (2) is driven by a voltage obtained by a voltage follower-type voltage generating unit (4) whose output voltage changes by following a supply voltage, and the voltage obtained by the voltage generating unit is applied as an offset compensating voltage, thereby simplifying the circuit of a Hall element portion. In addition, a forward threshold voltage and a reverse threshold voltage that are used in a forward comparator unit (6) and a reverse comparator unit (8), respectively, are separately generated by a first reference resistor unit (5) and a second reference resistor unit (7), thereby simplifying an adjustment operation at a comparator portion and improving the comparator accuracy.

Abstract: To produce a high current carring inductor with a high inductance value in space normally too small, a transformer is chosen which meets space requirements and has a primary winding of sufficient current capacity, but too little inductance. A bidirectional current source drives the secondary winding under control of a feedback circuit in response to sensed primary winding current to effectively multiply the primary winding inductance.

Abstract: A system allowing selective connection of various types of external apparatuses to a telephone set, which system comprises a plurality of switching circuits connected to the external apparatuses and a plurality of external apparatus interface circuit having mutually different characteristics and connected through the plurality of switching circuits to the external apparatuses, wherein any one of these switching circuits is turned on and at the same time the other circuits are turned off to selectively connect one of the interface circuits to one of the external apparatuses.

Abstract: An electronic hybrid circuit includes a differential amplifier having its non-inverting input coupled via a resistor to a four-wire input port and via a coupling transformer to a two-wire input/output port, its output coupled to a four-wire output port, and its inverting input coupled via a resistor to the input port and also coupled to an impedance network. The impedance network includes an inductive impedance which is coupled either to the amplifier output or to circuit ground, and which may be constituted by a gyrator or other electronic circuit which simulates an inductor.

Abstract: A temperature sensor located at a region being monitored controls an output switch that in one position when ambient temperature is below a predetermined temperature applies current to only a first loop circuit and in another position when ambient temperature is at or above the predetermined temperature applies current to only a second loop circuit. Currents in the first and second loop circuits are measured by ferrods to determine whether an over-temperature condition at the region monitored has taken place. An alarm circuit connected to outputs of the ferrods generates an alarm signal in response to a negative transaction of current in the first loop circuit or a positive transition of current in the second loop circuit. A failure in either loop circuit accordingly is insufficient to disable the system. A solid state timer periodically opens the second loop circuit to repeat the alarm signal when the second loop circuit is closed until corrective action is taken.

Abstract: A directional coupler transformer insensitive to data bus termination failures, includes a ferrite toroid core about which first through fourth windings are wound, the first and second windings being for connection in series with each conductor, respectively, of a data bus for sensing or generating data signal current, the third winding being connected in parallel with the data bus conductors for sensing or generating data signal voltage, and a fourth winding inductively coupled to the other three windings for either coupling data signals traveling in one direction from the data bus to a receiving unit, or coupling data signals from a transmitting unit to the data bus for transmission along the data bus in a given direction.

Abstract: The invention herein is fallback function communications device comprised of a microprocessor, utilized to perform a predetermined operation and processing of a predetermined input signal and then output a corresponding signal, as well as a minimum of one relay circuit having an amplifier circuit and a relay. The terminal at the first side of the relay is connected to the telephone line tip/ring terminal, while the terminal at the second side of the relay is connected to the Public Services Telephone Network (PSTN) tip/ring terminal of the microprocessor. An off-hook detection circuit is connected to the PSTN tip/ring terminal and also connected to the ring detection terminal of the said microprocessor. A dummy load circuit is connected to the tip terminal and the ring terminal of the PSTN. As such, in the event of Voice Over Internet Protocol (VOIP) system failure, the present invention is capable of automatically switching to the PSTN and thereby maintain telephone system operation.