Abstract: To enable a long distance prefix "1" to be added to the memory in a telephone set of the last number dialed, a permanent memory of "1" is provided which enables the prefix "1" to be dialed automatically prior to and in conjunction with automatic redialing of the last number dialed by pressing a single long distance redial key.

Abstract: An electric power circuit for telephone set use utilizing a power source drawn from a telephone circuit line. Alternating current components superimposed on a supply voltage, which is taken out by means of a by-pass capacitor, are delivered to a downstream-side of the common-base of an input-side transistor comprised in a current mirror circuit. A constant value of direct-current, which is the same magnitude as a potential difference between the supply voltage and a potential of the common-base of the current mirror circuit, is obtained at the input side transistor by varying the potential of the common base in accordance with fluctuations due to a.c. components superimposed on the supply voltage. An amplified direct-current is output from the output-side transistor capable of producing a magnitude of current in proportion to that of the input-side current.

Abstract: To allow a universal replacement telephone handset, an adaptive amplifier circuit uses DC power available from a host telephone set base to discriminate between low resistance and high resistance base power supplies. It emulates either a carbon microphone or an electret microphone, whichever is appropriate for the set base. The circuit couples a microphone (10) and an output terminal (2a) through a series connection of resistor (R1), input and output leads of an amplifier (12), and a sense circuit (22). The sense circuit controls two current sources (14),(16) in response to the shunt voltage and series current available from the telephone base. Current source (14) connects the amplifier output to an input terminal (1a) and acts either as a bias current source, or as an electronic switch that provides a short circuit from the microphone to the the amplifier output.

Abstract: An electrical telephone speech network is disclosed in which the transmitting and the receiving amplifiers are serially connected so as to reduce the minimum working current of the whole speech network. As a result, a telephone set in the network can operate properly with a much lower line current, and more extension telephones can be connected parallelly with the speech network. Further, a bias switching circuit is matched with the speech network. Thus, in pulse dialing mode, the line voltage drop of the network loop during "make" status is automatically decreased so that a pulse dialing signal received by the exchange can be more accurate. At the same time, in DTMF dialing mode, the voltage drop of the telephone set is automatically increased, for the purpose of providing a larger AC signal dynamic range to enable a telephone set to deliver a large DTMF signal and operate with a lower line current.

Abstract: A telephone set includes a volatile memory (14) for storing data such as telephone numbers or messages and a battery (17) for maintaining the data stored in the volatile memory (14). In order to prevent the data stored in the volatile memory (14) from being lost when the battery (17) is consumed, a detection circuit (18) detects the consumption of the battery (17) and supplies the voltage fed through a line from the telephone office side to the volatile memory (14) through a switch (19) on the basis of that detection. It is possible to transfer the data in the volatile memory to the non-volatile memory directly before the battery is consumed.

Abstract: A telephone station set (100) alerting arrangement preferably uses a a speakerphone loudspeaker (140) to produce audible alerting signals (e.g., ringing signals )from locally-generated (105, 115) alerting signals both when the set is on-hook and when the set is off-hook. The present state of the speakerphone control circuit (102) is used to control the volume of the produced audible alerting signals: high-volume alerting signals are supplied to the loudspeaker when the control circuit (102) is used to control the volume of the produced audible alerting signals: high-volume alerting signals are supplied to the loudspeaker when the control circuit is in talking state (202), and low-volume, attenuated alerting signals are supplied to the loudspeaker when the control circuit is in listening state (201). The appearance of alerting signals when the speakerphone control circuit is in idle state (200) causes the speakerphone circuit to make a transition to the talking state.

Abstract: A hands-free telephone assembly according to the present invention comprises a speech network mounted in a base and having an input channel and an output channel, the speech network being connected to a telephone interface which is selectively connectable to a telephone line. Also included are a gain-controllable amplifier in said input channel, a primary transducer including a primary speaker connected to the output of said gain-controllable amplifier, and a primary microphone, and a gain and frequency controllable amplifier connecting the primary microphone to said input channel. The primary transducer is mounted in a housing separate from the base, said housing being constructed and arranged so as to fit within the ear canal of a user and to be releasably maintained therein. Finally, the assembly contains a cancellation mechanism for suppressing positive feedback between the primary microphone and the primary speaker.

Abstract: A programmable telephone powered by a telephone line, and responsive to ringing signals for providing an automatic answer. A microprocessor in the telephone is powered by periodic signals during ringing intervals for executing instructions to count the number of ring cycles, and is placed in a sleep mode if such number does not exceed a predefined threshold. When the threshold number of rings occurs, the microprocessor places the telephone in a simulated off-hook condition for allowing programming of the memory thereof. The memory of the microprocessor is an EEPROM having a file allocation table with addresses pointing to an input dialing pattern table, an area code/exchange code table and to an output dialing pattern table. Multiple levels of user and software security codes are employed to provide a high degree of security to the programming of the telephone.

Abstract: A control circuit for an electrical telephone accessory detects if the telephone receiver is on the cradle, the telephone ringer is actuated, or if the telephone receiver is lifted from the cradle. The control circuit connects the electrical telephone accessory to a power supply source when the telephone ringer is actuated or when the telephone receiver is lifted from the cradle.

Abstract: An adaptive echo canceller for suppressing an echo in an input signal by a pseudo echo, includes a pseudo echo generation filter having a predicted impulse response sequence of an echo path as filter coefficients thereof for generating a pseudo echo, a coefficient renewal part for adaptively renewing the filter coefficients of the pseudo echo generation filter, and a part for suppressing an echo by the pseudo echo which is generated by the pseudo echo generation filter. The coefficient renewal part includes a part for dividing renewed filter coefficients into a plurality of groups each having a certain number of renewed filter coefficents, and a part for successively selecting one group with a predetermined period and carrying out a correction process with respect to the renewed filter coefficients within the selected group, where the correction process corrects an accumulation of errors of renewal processes.

Abstract: An interface between a bidirectional transmission channel with analog signals and four-wire input of a digital communication system. In order to enable a formatting of the interface as an integrated module in 10 V technology, a repeater or transformer is operated as an attenuation element in a lower frequency range and the transmission or, respectively, terminating impedance is selected such that all signalization voltages are transformed into a range that can be evaluated in 10 V technology, whereby, for suppressing higher-frequency noise signals, the signalization voltages are supplied via a low-pass filter to a ringing signal detector or, respectively, via a selective band-pass filter to a call charge signal detector.

Abstract: An echo canceller which incorporates an overlapping look-up-and-add structure is suitable for cancelling both the linear and nonlinear components of an echo. In the well-known overlapping look-up-and-add structure, the cancellation provided is the sum of a plurality of memory outputs wherein each memory is addressed by an associated transmitted symbol in a sequence of symbols along with one symbol immediately preceding and/or one symbol immediately succeeding each associated symbol. In accordance with the present invention, this structure is modified so that each memory is addressed by the plurality of bits representative of an associated symbol in the sequence of symbols along with less than all of the bits representative of one or more symbols adjacent to the associated symbol in the sequence.

Abstract: An automatic telephone dialer system using optical input of telephone numbers from printed materials. Numbers can be stored as bar codes (22) readable by a bar code wand (26) or as characters (24) readable by an OCR (Optical Character Recognition) scanner (106). When the number is read by the autodialer unit it is interpreted by a microcontroller (50) which commands a DTMF (Dual Tone MultiFrequency) generator (56) to send dialing signals to a telephone line (72). Dialing occurs when a sensor (68) detects that an attached telephone handset (74) is off-hook. Multiple numbers can be read into memory (42) and the next sequential number will be dialed after the telephone handset goes on-hook then off-hook. The sequence of numbers can be cleared by a reset switch (30). Bar codes are self checking and require only one scan. The autodialer unit can be configured to delete all scanned area codes or access codes.

Abstract: A device for controlling a cursor on a data terminal display screen. The device is in the form of a headset and includes an orientation sensor which provides an electrical signal related to the orientation of the device without it being adjacent to any fixed surface. The orientation sensor includes a hollow spherical housing having at least one light source/detector pair mounted opposingly in the inner wall, along an axis extending through the center point of the housing. The housing is half-filled with a transparent liquid having a specified viscosity and index of refraction and half-filled with air. Light beams emitted from the sources are refracted upon passing through the boundary between the air and the liquid. As the orientation sensor rotates with respect to the vertical axis, the changing refraction angle of the light beam causes the detector to sense changing intensities of light, which are representative of the angle of rotation.

Abstract: Method and apparatus for capturing and saving recently dialed telephone numbers and for redialing automatically a telephone number from among the most recently dialed telephone numbers. Embodiments of the present invention: (a) capture an outgoing telephone number when it is dialed by a caller; (b) enter the telephone number into a database comprised of the last N telephone numbers that were dialed, where N is a predetermined number of telephone numbers, while eliminating duplicative entries for a particular telephone number; (c) display the telephone numbers in the directory in response to caller input; and (d) cause a telephone number in the directory to be redialed in response to caller input.

Abstract: A conversion circuit for connecting a two-wire circuit and a four-wire circuit to each other comprises a transformer having a primary side and a secondary side, the primary side being connected to a two-wire circuit having a variable impedance, a first amplifying circuit having a first input terminal connected to the secondary side of the transformer for receiving an audio frequency signal from the two-wire circuit and a second input terminal, the first amplifying circuit having an output terminal connected to a reception-side line of a four-wire circuit, a second amplifying circuit having an input terminal connected to a transmission-side line of the four-wire circuit and an output terminal connected to the secondary side of the transformer for sending out an audio signal on the transmission-side line to the two-wire circuit, a plurality of impedance matching circuits having respective impedances each determined so as to simulate one state of the variable impedance of the two-wire circuit, and a switch for s

Abstract: A hybrid circuit which converts receiving side four-wire signals from a switching network into two-wire signals, supplies the same through line B and line A to a telephone terminal equipment, and converts two-wire signals supplied from the telephone terminal equipment through the line A and the line B to the switching network into transmitting side four-wire signals, including a pair of battery feeding and terminating resistors connected between power sources (GND and V.sub.BB) and the line B and line A and a receiving side mirror circuit and transmitting side mirror circuit both connected between the lines B and A.

Abstract: A circuit arrangement of simple structure for producing dialing pulses for a telephone transmission system so as to provide a relatively low insertion attenuation during transmission. The impedance of the transmission system should not be reduced. At loop closure the a.c. impedance of the circuit is high-ohmic and for d.c. current the circuit has a very low resistance. A switching apparatus is connected to the wires of a connecting line in parallel with the transmission system. The switching apparatus is arranged as a series connection of a bipolar transistor and a switching element consisting of a MOS field-effect transistor.

Abstract: In a noise cancellation system an adaptive filter produces a noise cancellation signal. The cancellation signal is compensated in response to indications of timing variations. For a linear traversal filter compensating coefficients (25) are provided which combine with, or relace, their respective primary coefficients when a timing variation occurs. Higher order compensating coefficients may be provided for selected taps and a modular structure is adopted thus facilitating implementation in integtrated form.

Abstract: A user can alternately send information to one of two parties on different telephone lines by mounting a microphone/speaker transducer in each ear, and connecting each transducer to a speech network device that is operatively connected to the respective telephone lines such that each transducer is connected to a different one of the telephone lines. The user may speak exclusively to only one of the parties by selectively muting the transmission of microphone signals through the speech network device connected to the telephone line connected to other party. Because the transducers are of the hands-free type, the user can easily manipulate the muting switch of one or the other of the speech network devices in accordance with which of the two parties to whom he wishes to speak in private.