Abstract: Methods and apparatus for using and/or switching to an auxiliary communication pathway to increase system reliability and/or reduce maintenance costs is disclosed. One feature is directed to a smart network interface device (SNID) implemented using latching relays. The SNID has very low power requirements and can be remotely controlled in a reliable manner through the use of simple tone signal commands over common POTS line pairs. Upon detecting a fault condition on a main line pair, the SNID is remotely instructed to disconnect the faulty line pair and switch the telephone customer's line connected to the faulty line pair to an auxiliary line pair. To operate in a POTS telephone environment without the need for an additional power supply, the SNID is designed to be powered from the power available from the auxiliary line pair. The power supply circuitry of the SNID is designed to have a near infinite input impedance with regard to input signals below twenty volts.

Abstract: A channel interface unit for interconnecting a two-wire transmission path which transmits analog signals and a digital signal transmission path. The channel interface unit includes a digital interface unit coupled with the digital signal transmission path and producing digital signals based on digital signals received from the digital signal transmission path, a converter for converting the digital signals to analog signals, a filter for removing noise, produced by the converter, from the analog signals, a driver, coupled with the two-wire transmission path, for amplifying the filtered analog signals, and a power supply for providing regulated voltage to the driver.

Abstract: A channel interface unit for interconnecting a two-wire transmission path which transmits analog signals and a digital signal transmission path. The channel interface unit includes a digital interface unit coupled with the digital signal transmission path and producing digital signals based on digital signals received from the digital signal transmission path, a converter for converting the digital signals to analog signals, a filter for removing noise, produced by the converter, from the analog signals, a driver, coupled with the two-wire transmission path, for amplifying the filtered analog signals, and a power supply for providing regulated voltage to the driver The channel interface unit also includes a device for decreasing effective capacitance by modifying the output impedance of the driver.

Abstract: A channel interface unit for interconnecting a two-wire transmission path which transmits analog signals and a digital signal transmission path. The channel interface unit includes a digital interface unit coupled with the digital signal transmission path and producing digital signals based on digital signals received from the digital signal transmission path, a converter for converting the digital signals to analog signals, a filter for removing noise, produced by the converter, from the analog signals, a driver, coupled with the two-wire transmission path, for amplifying the filtered analog signals, and a power supply for providing regulated voltage to the driver.

Abstract: A timing circuit and apparatus that utilizes this circuit. The apparatus is particularly suited for use with a telephone network interface, for substantially preventing a third party who gains access to the interface from placing an unauthorized telephone call through a network connection obtained through a jack, typically modular, located in a customer portion of the interface. Specifically, this apparatus is connected in series within the telephone company side of the interface to illustratively a ring lead of an incoming subscriber loop. In operation, the apparatus provides network access, by supplying loop current, on a timed periodic (repetitive) basis to a telephone (or other equipment through which a telephone call can be placed) plugged into the jack located within the network interface. Access is provided for a period of time that is sufficient to test loop current but is insufficient to allow the network to complete a call dialed from that telephone over this loop.

Abstract: Apparatus for disconnecting and reconnecting equipment to a telephone line in response to a signal sent over the telephone line. The apparatus includes a voltage threshold circuit, a voltage regulator circuit and a switching and timing circuit. The switching and timing circuit includes a first energy storage capacitor and a first discharge circuit. The switching and timing circuit further includes a second energy storage capacitor and a second discharge circuit and further includes a third energy storage capacitor and timing resistor. The first discharge circuit includes a first semiconductor switching device and a relay coil of a latching relay. The second discharge circuit includes a second semiconductor switching device and a second relay coil of the latching relay.

Abstract: Various embodiments of a ground start circuit suited for use in telecommunication applications, illustratively in conjunction with a ground start line, and a method for use in the circuit for invoking ground start operation on such a line are described. In essence, as soon as a telephone line is connected across the inventive ground start circuit, a potential difference that appears between a ring side of a two-wire telephone line and earth ground causes a control voltage internal to the circuit to increase in magnitude. Once this control voltage reaches a threshold value, then the circuit establishes a low impedance path between the ring side of the line and earth ground in order to place the line in an unbalanced condition. This low impedance path is maintained until a central office connected to the line at a remote end thereof senses the unbalanced condition and, in response, applies battery voltage to the line to cause loop current to flow therethrough, i.e.

Abstract: An apparatus and method for decoding ringing signals on a party telephone line coupled to the telephone line and a telephone instrument, according to the polarity of a d.c. voltage level present across the telephone line upon which ringing signals are superimposed and according to the grounded state of the telephone line. The apparatus comprises a discrimination circuit which supplies a selected one of the ringing signals to the telephone instrument via a ringing signal path to actuate the ringer of the telephone instrument. The apparatus further comprises a ringing signal rectification circuit connected to the telephone instrument via a voice signal path for preventing the ringing signal present on the telephone line from activating a ringer of the telephone instrument via the voice signal path. A switching circuit selectively connects the telephone instrument to the ringing signal path and the voice signal path.

Abstract: An apparatus adapted to be coupled into a party telephone line for selecting a ringing signal transmitted on the line from among a plurality of possible coded ringing signals that could be transmitted on the line and for coupling the ringing signal to a telephone is disclosed. The apparatus comprises a rectifier coupled to the party line for providing a rectified ringing signal, a first switch having the rectified signal as an input for reversing the polarity of the rectified signal at selected times, a second switch coupled to the first switch for selecting either the rectified ringing signal or the ringing signal itself and a third switch coupled to the second switch for coupling the selected signal to a telephone coupled to the third switch.

Abstract: A circuit for connection into a telephone line for detecting when a telephone instrument has gone off-hook and which is unaffected by the presence of a ringing signal on the telephone line. The circuit comprises a transistor switch, a first plurality of series connected diodes connected in series with the telephone line for developing a first voltage thereacross when the telephone instrument has gone off-hook, an RC circuit coupled to the first plurality of diodes for charging to the first voltage when the telephone instrument has gone off-hook after a time delay and for activating the switch, a second plurality of series connected diodes, the second plurality being greater than the first plurality, the second plurality of diodes being connected to the switch and to the first plurality of diodes for developing a second voltage thereacross during one half cycle of a ringing signal on the telephone line.

Abstract: A telephone line testing circuit for determining whether a fault exists on a telephone line entering a customer's premises or whether the fault exits in the customer's wiring and equipment. The testing circuit comprises a test switch, a polarity detector, a current detector, a dial tone detector and an indicator. The polarity, current and dial tone of an incoming telephone line signal are tested sequentially in the same circuit and in one operation such that if any one of the three characteristics of the entering telephone line contains a fault, the indicator will not generate a signal. When the entering telephone line signal has the correct operating polarity, sufficient operating current draw and a dial tone of the correct operating frequency, the indicator will generate a signal indicating that no fault exits on the entering telephone line.

Abstract: A wood thickness attachment for a jointer planer that has an angle/wood guide and cutter roller is provided. The attachment is attached and adjusted to the angle/wood guide and includes a roller guide that will engage a piece of wood which can be cut by the cutter roller and modified wood thickness attachment, leveling and adjustment features are built into the roller guide to compensate for various height thicknesses of the piece of wood.

Abstract: Apparatus is disclosed for disconnecting and reconnecting equipment to a telephone line in response to at least one signal sent over the telephone line. The apparatus includes a voltage threshold circuit, a voltage regulator circuit, a current chargeable element such as a capacitor, a discharge circuit, a switch and a switch control. The switch is coupled to the telephone line and to the equipment and disconnects the equipment from the line in response to the signal sent over the line. The threshold circuit is coupled to the line and receives the signal. It provides an output signal to the regulator circuit only when the signal on the line exceeds a threshold voltage level. The voltage regulator circuit regulates the voltage at the output of the threshold circuit and provides a substantially constant voltage to the chargeable element. Since the voltage applied to the chargeable element is known, the time required to charge the chargeable element can be precisely determined.

Abstract: Apparatus is disclosed for disconnecting and reconnecting equipment to a telephone line in response to at least one AC signal sent over the telephone line. The equipment can automatically be reconnected after a predetermined time period, or reconnected only after another AC signal is received. The apparatus includes digital circuits for detecting a signal within a predetermined frequency range which is present uninterrupted for a minimum time period to activate switching. The apparatus also includes digital timing circuits which can provide relatively long time periods during which the equipment is disconnected which do not utilize large energy storage devices. The digital circuits of the apparatus are operable at extremely low currents, e.g. less than 30 ua total drain. The regulator utilizes one or more light-emitting diodes drawing a current of only about 5 ua to generate a reference voltage.

Abstract: Apparatus is disclosed for disconnecting and reconnecting equipment to a telephone line in response to at least one signal sent over the telephone line. The apparatus includes a voltage threshold circuit, a voltage regulator circuit, a current chargeable element such as a capacitor, a discharge circuit, a switch and a switch control. The switch is coupled to the telephone line and to the equipment and disconnects the equipment from the line in response to the signal sent over the line. The threshold circuit is coupled to the line and receives the signal. It provides an output signal to the regulator circuit only when the signal on the line exceeds a threshold voltage level. The voltage regulator circuit regulates the voltage at the output of the threshold circuit and provides a substantially constant voltage to the chargeable element. Since the voltage applied to the chargeable element is known, the time required to charge the chargeable element can be precisely determined.