Abstract:
A method and/or device that may be used in locations where equipotential bonding is not practiced can be installed on a customer premises equipment device basis that provides over-voltage protection between the AC main and HFC ground planes. According to one aspect of the present invention, a bonding link is established between the AC main and the HFC coaxial braid that allows energy surges to bypass the CPE equipment and to be passed on to the AC mains, which are traditionally more equipped to deal with these large energy surges. According to another aspect of the present invention, an apparatus is disclosed that may be incorporated into any premises powered HFC CPE device for protection. The apparatus provides a surge energy bypass path around the CPE device being protected and allow voltage differentials to be normalized between systems.
Abstract:
A system comprising customer premises equipment including a reverse power supply unit (40) and an access node (90) to which the customer premises equipment is connected for permitting telephony devices connected to the customer premises equipment to make and receive telephone calls via the customer premises equipment and the access node. The reverse power supply unit is suitable for supplying electrical power from the customer's premises to an access node via a twisted copper pair (8), the reverse power supply unit including a power consumption signature detector (212) operable to detect if the power drawn from the reverse power supply unit corresponds to a signature power consumption pattern indicative of a telephony device being in or transitioning into an off-hook state when connected directly to the reverse power supply unit and not being connected via a current limiting interface. The customer premises equipment also includes a current limit arrangement connected to a customer premises wiring for limiting the amount of current and/or the maximum rate of increase of current which can be drawn by a telephony device connected to the customer premises wiring to be no greater than a predetermined amount or rate, the customer premises wiring being connected to the twisted copper pair in such a manner that voice signals can be transmitted from the telephony device to an access node to which the twisted pair is connected. The access network unit (90) includes a rate of change of current limitation device (91) wherein the rate of change of current limitation device has one or more of the following properties: a maximum rate of change of current draw of less than 150mA/s when connected to a 50V dc power supply; and the inclusion of a gyrator (92) for performing the rate of change of current limitation providing a predetermined inductance in order to provide a predetermined maximum rate of change of current draw when increasing its power consumption from a specified dc power source.
Abstract:
A method is provided for migrating at least one of a plurality of subscribers from a first service connecting the subscriber to an exchange to a second service connecting the subscriber to a FTTx node, the subscriber being connected to the first service via a subscriber line. The method includes establishing a connection between the FTTx node and the subscriber line at a node connection point; establishing a connection between the FTTx node and the exchange at the node connection point; and remotely activating the first service at the exchange and deactivating the second service at the FTTx node, or remotely deactivating the first service at the exchange and activating the second service at the FTTx node. Throughout the process, the subscriber remains physically and simultaneously connected to both the FTTx node and the exchange at all times.
Abstract:
A method and/or device that may be used in locations where equipotential bonding is not practiced can be installed on a customer premises equipment device basis that provides over-voltage protection between the AC main and HFC ground planes. According to one aspect of the present invention, a bonding link is established between the AC main and the HFC coaxial braid that allows energy surges to bypass the CPE equipment and to be passed on to the AC mains, which are traditionally more equipped to deal with these large energy surges. According to another aspect of the present invention, an apparatus is disclosed that may be incorporated into any premises powered HFC CPE device for protection. The apparatus provides a surge energy bypass path around the CPE device being protected and allow voltage differentials to be normalized between systems.
Abstract:
The present invention relates to a transmission arrangement (100; 200) comprising a line driver (130) for driving a transmission line (L) with a transmit signal (Vs) comprising successive transmit DMT symbols (S1 to S5), and a clamping device (152; 252; 254) for protecting the line driver from signal surges occurring over the transmission line. in accordance with an embodiment of the invention, the transmission arrangement further comprises a peak amplitude equalizer (111) configured to increase the amplitude of selected signal crests (V1P; V2P) of respective transmit DMT symbols (S1; S2) up to a desired crest value (VOPT) for short recharge of the clamping device. The present invention also relates to a method for driving a transmission line (L) with a transmit signal (Vs) comprising successive transmit DMT symbols (S1 to S5).
Abstract:
A protection device (10) uses a single-coil (15) latch relay (11) to decouple a telephone and/or data installation from DC transmission lines (12) in the event of a line AC/overvoltage disturbance. A trip circuit (19) and a reset circuit (21) are respectively connected to normally-closed (OUTA1, OUTB1) and normally-open (OUTA2, OUTB2) terminals of the relay to monitor the line voltage using an earth connection as a reference voltage, supplying respectively trip (23) or reset (25) currents to the coil for switching the relay. Hence, the protection device may operatively tolerate an inexpensive high-resistance earth connection. The reset current is supplied to the relay coil by a transistor circuit (Q1, Q2) only after the disturbance has ceased, the nominal transmission voltage has been restored and the line has stabilized for some seconds.
Abstract:
A surge reset circuit (200) used to automatically reset a surge protection circuit within a telephone line interface circuit. A sensor (300) (e.g., a zenering device) advantageously generates a voltage level representing current draining out of the transient voltage suppression portion of the surge protection circuit after a transient energy surge. If the current is draining, which may indicate a potential lockup situation, feedback circuitry (305) generates a reset feedback signal that is provided to a cutoff device (330). The cutoff device, in response to receiving the feedback signal, disables a current limiter portion of the surge protection circuit to reduce the current draining from the transient voltage suppression portion. As the current level is reduced, the transient voltage suppression portion will reset when the current drops below a threshold value or is substantially eliminated. As a result, the feedback circuitry removes the reset feedback signal from the cutoff device to re-enable the current limiter (34).
Abstract:
A protection arrangement for a telephone subscriber line interface circuit is disclosed. The arrangement is particularly useful for protecting an electronic telephone set from over-voltage and over-current fault conditions. The arrangement provides a FET (34) that operates in saturation mode to connect an office battery (22) to the subscriber line under normal operation. The FET (34) also provides isolation capabilities for protecting the line circuit from an over-current condition on the subscriber line. Over-voltage protection is provided by way of an isolation relay (12) between the line circuit and the subscriber line. Both the FET and isolation relay are operated by a controller (16) that uses timers in the methods of over-voltage and over-current protection that it performs. A further capability of the arrangement is that is resets itself after the fault condition has ended. This feature is particularly useful in the case of fault conditions of short duration.
Abstract:
A telephone line interface circuit with d.c. amplifiers (12) coupled to tip and ring paths is protected against transient voltages by a crowbar-type protection device (52) coupled via a diode bridge (28, 30) to the tip and ring paths, positive and negative terminals of the diode bridge being connected respectively to ground and via a diode (54) to a negative supply voltage line for the amplifiers. The diode prevents discharge of a capacitor (26), coupled between the negative supply voltage line and ground, through the protection device when it conducts. A locked up state, in which the amplifiers maintain holding current to the protection device after a transient voltage, is avoided by further diodes (56, 58) coupled from the negative terminal of the diode bridge to inputs of the amplifiers, or by controlling a current limiter (34) to interrupt current to the capacitor when the diode is reverse biased, so that the capacitor discharges. The current limiter includes a resistance (38) and inductance (40) in series for sensing current, whereby initial charging current for the capacitor is reduced on closing of relay contacts (K1, K2) in series with the current limiter, and relay contact deterioration is avoided.