Abstract: A device includes a controller. An input is coupled to the controller, the input having a set of wires to couple to a doorbell to receive an AC signal when the doorbell is actuated. An analog to digital converter is coupled to the input to convert the received AC signal to a digital signal and coupled to the controller to provide the digital signal to the controller. A transmitter is coupled to the controller to wirelessly transmit signals from the controller representative to actuation of the doorbell. An enclosure contains the controller, input, analog to digital converter and transmitter and has an opening to provide a passage outside the enclosure for the set of wires. The controller may be programmable via an optical signal and may provide alerts responsive to a temperature sensor.

Abstract: Methods and apparatus are disclosed for identifying defective communications lines. The method generally involves passively detecting signals symptomatic of and generated by a defective communications line rather than by a user accessing a communication network via the line. One alternative involves monitoring calls to a selected number having low digit and set values. Analysis of the pattern of calls to the selected number, or directly monitoring the frequencies upon the communications line, identify calls that are effectively generated by defects in a communications line rather than legitimate calls generated by network users. Spurious calls are associated with the originating communications line. The line can then be automatically tested or service dispatched. More automated alternatives are also disclosed that make use of switch reconfigurations. Central office switches may be programmed to detect a variety of events that indicate a spurious pulse or seizure is being generated by a communication line.

Abstract: Negative-resistance resonant tunnel diodes (RTDs) perform a complete set of logic functions with a single basic configuration. Inputs feed through Schottky diodes to a transfer RTD coupled to a clocked latch having two RTDs in series. Cascaded gates are driven synchronously by multiple clock phases or by asynchronous event signals. An XOR configuration also provides logical inversion.

Abstract: An improved automatic gain control circuit for a telephonic headset having a gain control stage in the audio signal path to attenuate tones, in which the gain is controlled by a control signal. A peak filter and an average filter generate signals proportional to the peak and average levels of the input signal, respectively. The signals are compared and a control signal is generated based on the relative signal levels. When the average signal exceeds a predetermined fraction of the peak signal, the circuit recognizes the signal as a tone and generates a control signal that causes the gain control stage to increase attenuation of the input signal.

Abstract: Negative-resistance resonant tunnel diodes (RTDs) perform a complete set of logic functions with a single basic configuration. Inputs feed through Schottky diodes to a transfer RTD coupled to a clocked latch having two RTDs in series. Cascaded gates are driven synchronously by multiple clock phases or by asynchronous event signals. An XOR configuration also provides logical inversion.

Abstract: A tone reduction circuit for headsets designed to attenuate high frequency signals while permitting low frequency signals to pass undistorted. Input signal is supplied to a low-pass filter, a high-pass filter and an automatic gain control circuit (AGC). Outputs from both filters are input to a comparator, with the comparator output connected to the gain control input of the AGC. The AGC is configured to attenuate only the higher frequency signals. Thus, the comparator output controls gain imparted to the output signal produced by the AGC. The comparator output signals no gain in the automatic gain control circuit when low-pass filter output is greater than high-pass filter output, but when the high-pass filter output is greater than the low-pass filter output the comparator controls the automatic gain generator to attenuate the higher frequency input signal in proportion to the difference between high-pass filter output and low-pass filter output.

Abstract: An improved automatic gain control circuit for a telephonic headset having a variable gain stage in the audio signal path, the gain of which is controlled by a control signal appearing across a capacitor. A peak detector is used to detect the presence of peak signals above a predetermined minimum threshold level and a substantially conventional automatic control network is formed around the capacitor in response thereto. During the absence of such peak signals the capacitor is disconnected from the AGC control network and holds the control signal at a constant level. Passage of a predetermined period of time in which no peak signals above the threshold are detected causes a switch to connect a nominal gain setting network to the capacitor to establish a quiescent no signal gain for the circuit which is lower than the maximum gain which the AGC can achieve when it is active.