Abstract: A public telephone network to portable telephone interconnection device (20) is provided. At least one transceiver (30a-n) interconnects a plurality of portable telephones (12) to the public telephone network (16). A channel monitor (38) monitors the transceivers (30a-n and 82) to provide information. At least one information transceiver (82) interconnects the plurality of portable telephones (12) to and is responsive to the monitor (38) for transmitting (104) the information to the plurality of portable telephones (12).

Abstract: An annunciator for indicating the removal of an electrical plug from an electrical receptacle. The electrical receptacle includes neutral switching contacts actuated in response to the insertion of a plug into the receptacle. An input circuit in the annunciator apparatus monitors the state of the neutral switching contacts and couples signals produced when a plug is removed to a latching circuit thereby to produce an audible or electrical indication of plug removal. The annunciator circuit does not provide an alarm in response to the insertion of a plug or to an absence of a plug.

Abstract: A diaphragm for microphones having a laminate structure which imparts damping characteristics to the diaphragm is disclosed. The laminate comprises upper and lower resilient layers composed of a plastic film. The upper and lower layers constrain a center layer composed of an elastomeric material having a high dissipation of vibratory shear motion. Manufacturing techniques for making such diaphragms are disclosed.

Abstract: A hearing aid includes a filter in an electrical feedback path, the characteristics of which filter are calculated to model acoustic coupling between the receiver and microphone of the aid. A limiter is inserted in the main electrical pathway between the microphone and the receiver to provide stability in the presence of sudden sound bursts. A noise signal is injected continuously into the electrical circuit and is used to adapt the characteristics of the filter to accommodate changes in the acoustic coupling. The level of the noise signal can be varied to match changes in residual signal level to maintain signal to noise ratio and to optimize rate of adaption commensurate with satisfactory hearing function while the noise itself is unobtrusive to the user.

Abstract: An in-the-ear hearing aid comprises a housing having a face plate that has a first opening for a battery compartment and a second opening connected to the first opening. A lamina is constructed as a carrier for a hearing aid component and is introduced into this second opening, and the lamina is secured in this second opening, even when the battery is removed from the battery compartment, and is, nonetheless, removable from the hearing aid without exertion of great force. To accomplish these goals, a holding arrangement is formed in a portion of the edges of the lamina and the second opening.

Abstract: A video teleconferencing system includes a plurality of terminals, a server including a storage for storing input information, and a network coupling the terminals to the server, where the input information is supplied from each terminal to other terminals from the server.

Abstract: A frequency synthesizer for producing an output whose phase and/or frequency can be finely adjusted under digital control. The synthesizer utilizes a phase lock loop including a phase detector responsive to a prescale divide-by-N frequency divider and a feedback divide-by-M frequency divider to product an output signal F.sub.OUT. The phase of F.sub.OUT can be shifted by a small increment by slightly adjusting the values of the divisors M and N.

Abstract: A network of local area audience response systems is coupled together at a central audience response processing station by a satellite communication system for real time audience response analysis, nationally or internationally. Each local area station and each response unit may be identified and verified by allocation of specific time slots for response preferably synchronously related to a TV picture program transmission carrying the audience questions to be answered. Wireless transmission of the question and answer signals in digital format of beeps of a single frequency keeps transmission channels narrow. The system may be operated in conjunction with TV broadcasting or independently.

Abstract: A digital error corrected Fractional-N synthesizer having a reference frequency generator for providing a reference frequency signal and a voltage controlled oscillator for providing an output signal having a frequency equal to a fractional multiple of said reference frequency signal. The output signal of the Fractional-N synthesizer includes a residual error signal. An error signal compensation circuit is provided for generating a correction signal to cancel the residual error signal. In a preferred embodiment, the reference frequency signal is delivered to a loop phase detector which provides an error voltage proportional to a phase difference between the reference frequency signal and a feedback signal. The frequency of the output signal, which is a fractional multiple of the reference frequency signal and proportional to the error voltage, is operated upon by a plurality of divisors of a loop divider circuit to provide the feedback signal.

Abstract: A receiver having a signal path incorporating a tuner, a demodulator circuit for supplying a stereo multiplex signal having a baseband stereo sum signal (L+R), a 19 kHz stereo pilot and a stereo difference signal (L-R) which is double sideband amplitude-modulated on a suppressed 38 kHz subcarrier, a sampler for converting an analog signal into a time-discrete signal and a stereo decoder for time-division multiplex decoding of a time-discrete stereo multiplex signal into time-discrete left and right stereo signals. In order to realize an effective selection of the stereo multiplex signal by an easily integrable low-pass filter, the stereo decoder includes a time-discrete halfband low-pass filter circuit having a finite impulse response, with a transition band which is substantially located in the frequency range of said modulated stereo difference signal and with a half-value transfer which is located at the frequency of said 38 kHz stereo subcarrier.

Abstract: A radio pager system and pager terminal apparatus used in the system are disclosed. A pager signal to be transmitted includes destination information and message specifying information for specifying a message to be transmitted. The pager terminal apparatus includes a receiver for receiving an incoming pager signal, a detector for detecting that the received pager signal is a signal destined for the pager terminal apparatus, an extracting circuit for extracting message specifying information from the pager signal transmitted to the pager terminal apparatus and message displaying apparatus responsive to the extracted message specifying information for displaying a message corresponding to the extracted message specifying information in a visually recognizable manner. The radio pager system includes the above pager terminal apparatus, a station for transmitting via radio a pager signal, and transmission terminal apparatus for supplying the destination information and the message information to the station.

Abstract: A method and an apparatus for following a vehicle are disclosed by which the distance from a vehicle to a preceding target vehicle running ahead thereof can be exactly measured and, based on the thus measured distance, an appropriate vehicle following window can be automatically set with respect to a target image of the preceding vehicle at the start of vehicle following. Images of objects including the preceding vehicle are taken from two different points. The distance to the preceding vehicle is measured based on the images thus taken from the two points. On the basis of the measured distance, the size of an image-following window to be set within an image area displayed on a screen of a display is determined for following the preceding vehicle. The image of the preceding vehicle is found among various images of objects in the image area on the screen, and the position of the window on the screen is properly set and then temporarily stored in a memory.

Abstract: A single-channel circuit for a hearing aid for persons with an impaired hearing faculty has a pre-amplifier and an output amplifier, a microphone and an earphone, as well as a full-wave rectifier circuit for producing a control voltage for a voltage-dependent attenuator connected to the pre-amplifier. In order to allow a favorable speech audibility characteristic over the entire amplification range, a voltage-controlled filter is provided for a single-dependent change in the frequency response. The control input of the filter is connected to the rectifier circuit. The filter is connected to the rectifier circuit via a time function element.

Abstract: CMOSFETs control the power in a bipolar logic gate to regulate its operating speed and hence its delay. In a specific embodiment of the invention, an n-channel CMOSFET controls the constant current through an emitter-coupled current switch, comprised of a pair of bipolar integrated circuit transistors. A p-channel CMOSFET, in series with each collector of the switch pair, establishes the collector voltage so as to maintain constant the output swing of the gate as the power through the gate is varied in order to regulate the gate delay. An error signal, indicative of factors that can cause variations in gate delay and the inverse of the error signal are generated by an on-chip circuit. The error signal is coupled to the n-channel CMOSFET and the inverse of the error signal is coupled to the p-channel CMOSFET. Thus, as the switch current is decreased in order to increase the gate delay, the collector impedance is simultaneously increased so the collector voltage, and hence the gate swing, remains constant.

Abstract: A ground bouncing reducing circuit comprises a first control means, a second control means and an output means for generating an output signal at a fourth output terminal. The first control means generates a first control signal at a first output terminal and a second control signal at a second output terminal in response to an input signal. The first control signal and the second control signal are not asserted at the same time. The second control means generates a third control signal at a third output terminal in response to the first control signal and the second control signal. The ground bouncing phenomenon is reduced when the output signal changes state.

Abstract: In a cellular mobile telephone system wherein a mobile station is provided with a status indicator which provides a HOME indication when the mobile station communicates with a base station in its home system and a ROAM indication when the mobile station communicates with a base station in a "visited" system, the particular indication that is provided by the mobile station is dependent upon the system identification data (SID) that is received from the base station with which the mobile station communicates. The mobile station also includes a status order control message sensor for sensing an indicator status order control message transmitted by the base station which serves to selectively activate or deactivate the status indicator at the mobile station, notwithstanding that the indicator had been activated previously by the received SID.

Abstract: A facsimile machine which is coupled to a telephone line and a telephone set, where the facsimile machine connects the telephone set to the telephone line in a telephone mode and disconnects the telephone set from the telephone line in a facsimile mode so as to use the telephone line as a communication line for a facsimile communication, and the facsimile machine is connectable to a communication equipment via an interface unit which is designed exclusively for the communication equipment. The facsimile machine includes a single connector including signal lines for receiving and transmitting signals for coupling the facsimile machine to the interface unit, a single switch coupled to the connector for arbitrarily selecting the communication line to the telephone line in a first mode and to the communication equipment in a second mode, and a communication part for making a facsimile communication using the communication line which is selected by the switch.

Abstract: An acoustic transducer is disclosed for incorporation into an engine exhaust system or other gas carrying duct. The transducer produces pressure variations within the duct in accordance with an applied electrical signal. The transducer is especially suitable for use as part of a noise cancellation system whereby inverse pressure variations produced by the transducer cancel noise propagating in the duct. The design of the transducer allows its use when the duct is one carrying high temperature gases such as an automobile exhaust pipe.

Abstract: A data communication apparatus operates in a first switching mode in order to switch over between data communication and speech communication depending upon whether or not a signal indicating data communication mode is received within a predetermined period of time; a as well as second switching mode which switches over between data communication and speech communication depending upon whether or not a response signal to a procedure signal is received within a predetermined period of time. The apparatus has a detector that detects a state of the apparatus, and it selects one of the first and second switching modes.

Abstract: The invention relates to a supporting structure of a diaphragm of a dynamic microphone. A viscous liquid is filled in the inside of the peripheral edge portion of the edge portion of the diaphragm, thereby supporting the diaphragm to the casing through the viscous liquid. On the other hand, the peripheral edge portion of the diaphragm is fixed to the casing by a fixed ring and the viscous liquid is filled between the fixed ring and the front and rear surfaces of the peripheral edge portion of the edge portion of the diaphragm. With the above structure, by supporting the diaphragm to the casing through the viscous liquid, the liquid also moves in accordance with the vibration of the diaphragm without blocking the vibration of the diaphragm. Therefore, it is possible to certainly prevent the occurrence of the resonance at a special frequency.