Abstract: A telephone station subscriber line interface circuit for connecting a telephone subscriber station to a telecommunications transmission line comprises a loop current sensing circuit for providing an output signal proportionately representative of DC resistance in the telecommunications transmission line. A ring-side driving circuit is coupled to the loop current sensing circuit and is responsive to the output signal for providing an alternating current voltage source and a direct current voltage source to a transmit amplifier in periods of high constant DC resistance in the telecommunications transmission line, the ring-side driving circuit maintaining the output of the alternating current voltage source constant to the transmit amplifier and automatically transferring from a constant direct current voltage source to a constant direct current current source in the event of a decrease in the DC resistance in the telecommunications transmission line sensed by the loop curent sensing circuit.

Abstract: A toy type children telephone set, which mainly comprises a full functional telephone printed circuit board (abbreviated TPCB thereafter). The TPCB is encased in a toy-shaped outer case, instead of a traditional ringing bell. The TPCB is provided with an IC sound generator circuit, which produces a crying, laughing, or singing sound correlating to the embodied toy shape of the outer case when this telephone set is rung. Moreover, in the audio circuit of this TPCB, it is provided with an audio signal conversion circuit, so that through a bridge inverter it controls the rotation of a permanent magnet motor, this motor in turn drives the upper and lower lips at the head portion of the toy-shaped outer case to open or close by following the audio sound signal fluctuation via a driven mechanism and leaf spring switches, which attracts the children to use this telephone set happily.

Abstract: An echo suppressor for a communication system wherein a signal sent to a transmitting line is returned to a receiving line with some delay. The suppressor comprises an attenuator for attenuating the amplitude of a received speech signal. The transmitting speech signal amplitude level is compared to the amplitude of a receiving speech signal, and according to the result obtained, a signal for controlling the signal attenuation of the attenuator is generated. The delay time, until the attenuation control signal operates on the attenuator according to a change in the amplitude level of the receiving speech signal, is controlled. The controlled delay time is normally held at a predetermined maximum value, and is minimized when a change in amplitude of the receiving speech signal indicates a beginning of speech. Thus, an echo of the speech uttered by a near end user can be suppressed without impairing a beginning of the speech signal uttered by a far end user.

Abstract: A telephone line circuit transformer couples tip and ring leads of a telephone line to a telephone facility. Tip and ring transformer windings are connected in series with the respective tip and ring leads, tip and rings feed resistors and terminals of a battery power source for supplying energizing current to the telephone line. A capacitor is connected between a junction of the tip winding and the tip feed resistor and a junction of the ring winding and the ring feed resistor. A compensating circuit is connected to drive a compensating winding in current opposing relationship with respect to differential alternating current signals in the tip and ring windings and being within a range of voice frequencies within which an impedance of the capacitor is significantly shunted by the feed resistors.

Abstract: An animated telephone annunicator apparatus provides realistic movements so that a user of the apparatus appears to converse with the apparatus. The apparatus receives telephone signals, and in response to these received signals moves portions of the apparatus in synchronism with the signals. As a result, the apparatus appears to realistically speak the words of a calling party.

Abstract: A hybrid alphanumeric directory comprises a portable notebook containing a plurality of loosely bound pages, each of which has several writing areas where alphanumeric information can be entered. The writing areas are on each page in the same relative position. When the notebook is placed on the receiving surface of an electronic unit, an arrangement is provided to determine which page is open and this automatically associates the push-buttons with the respective writing areas of the open page. Data associated with the writing areas are electronically stored. When a push-button beside a writing area of an open page is depressed, an operation associated with the stored data pertaining to that writing area is automatically initiated. The directory is particularly useful as a telephone directory, in which case the data are stored telephone numbers. Depression of one of the push-buttons causes the stored telephone number to be automatically dialed.

Abstract: An echo canceller determines the optimum value of the required digital filter coefficient from values obtained by measuring a plurality of samples of the echo signal and by measuring, for each of a predetermined number of such samples, the replica signal sample factors which, when multiplied by the filter coefficients and summed, cancel the echo signal sample. The echo signal samples as well as the factors used to determine the replica signal samples are both measured in a way that reflects the actual environment in which the echo canceller is used. To measure each of the factors of the replica signal sample corresponding to an echo signal sample, an input signal is applied to the receive path, the filter coefficient corresponding to the factor is set to a non-zero value and the other filter coefficients to zero, and the resultant replica signal sample is then measured. It is not necessary for the echo signal and replica signal measurement to be made concurrently, or from the same location.

Abstract: A lock-out plug is provided for preventing unauthorized use of a telephone by preventing connection thereof to an operative telephone jack. The lock-out plug comprises a compact plug fitting having a size and shape to fit snugly into an open receptacle of a standard modular type telephone outlet jack. An angularly set threaded bore is formed within the plug fitting such that a forward end of the bore is disposed within the telephone receptacle and a rearward end of the bore is exposed to the exterior of the receptacle when the plug fitting is seated therein. A set screw is received within the bore and includes a forward end locking tip for binding engagement with a side wall of the telephone jack to lock the plug fitting in place and thereby prevent unauthorized connection of a telephone to the jack. The head of the set screw is accessible from the exterior of the jack preferably by engagement with a specialized tool to advance or retract the locking tip relative to the jack side wall.

Abstract: A telephone keypad assembly including a one-piece deformable membrane for sealing the keypad assembly from the environment. The deformable membrane has an upper surface for mating with keypad pushbuttons and a keypad pushbutton housing unit, and a lower surface including a contact actuator for making contact with electrical switch contacts. The membrane forms raised areas or domes which bias the keypad pushbuttons and biasingly resists movement of the contact actuator toward the electrical contacts. The keypad assembly including switch contacts is protected from moisture, dust and other corrosive elements by the seal formed between the housing unit and the deformable membrane.

Abstract: The invention provides a tip party identification facility in association with a subscriber line interface circuit. The tip party identification facility takes advantage of a shutdown feature and the output of a common mode error amplifier of the subscriber line interface circuit. The use of this facility enables the central office to determine whether the tip party or ring party is off-hook for billing purposes.

Abstract: An office line interface circuit includes a DC circuit for extracting a DC signal component from the office line current, an AC circuit for extracting an AC signal component from the office line current to supply the extracted AC signal component to the receiver of a telephone set, an impedance circuit switchably connected to the office line, and a switching circuit for connecting the impedance circuit to the office line when the extracted DC signal component exceeds a predetermined level to maintain at a substantially constant value the impedance of the office line as viewed from the telephone set. With this interface circuit, the sidetone preventing circuit for the telephone system can operate satisfactorily without complicating the construction under any office line condition.

Abstract: An adaptive echo suppressor is provided at each local station in a data transmission system for transmission of local data from a local station to a remote station over a transmission medium exhibiting an echo and simultaneous transmission of far end data over said medium from said remote station. The echo suppressor comprises an adaptive echo suppressor located at said local station and comprising: an adaptive digital filter connected to receive the local data a.sub.x and a clean signal e.sub.k substantially free of echo and arranged to deliver on an output an estimation o.sub.k of the echo of the local data by multiplying a vector of coefficients C.sub.k with the local data a.sub.k, said vector having an adaptation algorithm:C.sub.k+1 =C.sub.k +.mu.a.sub.k *.multidot.f(e.sub.k)wherein .mu. is a predetermined incrementation step, a.sub.k * is a conjugated value of the local data a.sub.k, and f is a predetermined function of e.sub.

Abstract: The present invention describes a low power consumption type subscriber line interface circuit (SLIC). The SLIC described in the present invention includes a first pair of potential detectors each of which detects the potential difference between each corresponding subscriber line and a first predetermined value, a second pair of potential difference detectors each of which detects a potential difference between each corresponding subscriber line and a second predetermined value, a pair of signal adder circuits each of which sums output signals from one of the first potential difference detectors and one of the second potential difference detectors, and a pair of amplifiers each of which amplifies each output signal from each signal summing circuit and returns a direct current to the each of corresponding subscriber lines.

Abstract: A channel unit interface circuit for interconnecting a two-wire, bidirectional signal transmitting means and a four-wire signal transmitting means in a communication system includes a tip terminal line driver, a ring terminal line driver, a voice sense amplifier, a balance network, A/D signal processing circuit, D/A signal processing circuit, filter network, a voice codec/PCM filter, a channel logic circuit, and a DC-to-DC converter. The channel unit interface circuit is suitable for use with substantially all of the different alarm-signalling techniques utilized by the various alarm companies for connecting their equipment to a channel bank coupled to the four-wire means. The interface circuit simulates a transmission line or cable over carrier in the frequency range of DC to 3.5 KHz with an amplitude variation between +110 to -200 VDC.

Abstract: A vehicular steering wheel telephone apparatus is set forth wherein a centrally mounted telephone unit is positioned medially of a vehicle-type steering wheel. Positioned in overlying relationship to said telephone unit is a pair of voice receiving speakers. In underlying relationship to said telephone unit is a pair of voice transmitting microphones. An overlying pivotal closure releases the telephone for use by releasing a switch hook exposing the telephone unit for operation. Optionally, a switching means is available for switching the receiving speakers for utilization with automobile stereo speakers.

Abstract: A multiple dwelling interface box has a plurality of individual customer compartments to provide distribution to individual customers from one secure compartment housing communication company equipment. The box will contain up to six single or six two line modular customer interfaces. The invididual securable compartments are provided for easy invididual subscriber access on a panel or partition that hinges to provide access to the telephone company equipment, but which panel can be locked to prevent customer access to the communication company equipment.

Abstract: A noise cancelling microphone for location inside an apertured mouthpiece region of a telephone handset comprises a housing with a face for securement in contact with the inside of the mouthpiece region. A cavity accommodates a vibratable diaphragm. A first sound path is provided to a front surface of the diaphragm by way of an opening in a central region of the face of the housing and apertures in a central portion of the mouthpiece region of the handset. A second sound path, physically separated from the first, is provided to a rear surface of the diaphragm by way of an opening in an outer region of the face of the housing and apertures in an outer portion of the mouthpiece region. The separated sound paths are extended by securing an upstanding member, such as a hollow truncated cone, externally on the mouthpiece region to separate the central and outer apertures.

Abstract: A power circuit for supplying power to a device, which is connected in parallel with a telephone to a telephone line to that power is normally supplied to it from the central telephone office, includes batteries and a switching circuit such that the power source for the device is switched to these batteries when a voltage drop in the normal power source is detected.

Abstract: An adaptive expander for telephones reduces the gain of a transmitting amplifier in proportion to the intensity of the background noise. Gain reduction occurs when the user is not speaking into the handset microphone. When the user is speaking, however, the gain of the transmitting amplifier is restored to its normal level. Noise is distinguished from speech via long-term averaging of the microphone output signal, and a circuit that precludes the magnitude of the long-term average voltage from ever exceeding the short-term average voltage. The present invention is used in full duplex arrangements where simultaneous transmission in both directions is possible rather than in half duplex arrangements, such as a speakerphone, where transmission occurs only in one direction at a time.

Abstract: An electronic speech circuit configuration includes first and second line terminals to be connected to a telephone line. An AC circuit portion includes a modulator circuit for generating a line transmission current. A DC circuit portion supplies energy and generates a DC current/voltage characteristic curve. The DC circuit portion includes a reference potential source and a decoupling capacitor. A current sensing resistor is provided. A high-speed control amplifier has a control circuit and controls current through the current sensing resistor. A buffer capacitor is provided. Output terminals are connected to the buffer capacitor for the connection of external components. The DC circuit portion also includes a current toggle circuit connected upstream of the buffer capacitor. The current for feeding the buffer capacitor flows through the current sensing resistor connected to the first line terminal.