Abstract: A client premises digital subscriber line (DSL) modem having multi-mode capability is disclosed. In initialization, the modem estimates whether channel conditions are such that digital processing of the received data according to a lower data rate DSL standard, such as ADSL2, may result in a higher effective data rate than receipt and processing according to a higher data rate DSL standard, such as ADSL2+. If so, the DSL modem configures itself, such as by configuring its filter characteristics and sampling frequency, to receive and process data according to the lower data rate DSL standard; the transmitting modem, for example at a central office or service area interface, may continue to operate according to the higher data rate standard (with its bit loading corresponding to a subset of subchannels). The receiving DSL modem processes the payload data according to the lower standard, while processing control messages according to the higher standard.

Abstract: An upstream signal optimizer for use with a digital subscriber line (DSL) modem, a method of optimizing an upstream signal and a transmitter associated with a DSL modem. In one embodiment, the upstream signal optimizer includes (1) a signal adapter configured to shape a frequency domain of an upstream signal and (2) an adapter controller coupled to the signal adapter configured to control operation of the signal adapter based on a training sequence of the modem.

Abstract: A method of resynchronizing data transfer between a first modem assigned to a central office and connected by a dedicated line a second modem assigned to a remote subscriber following a fault caused by a ringing signal. A ringing ID is set up in the central office modem as soon as a ringing signal is to be sent to the subscriber modem, and a ringing alert is transferred to the connected subscriber modem. Transmission of the pilot tone accompanying the data transfer set by the central office modem is interrupted as is the clock frequency synchronization implemented during data transfer in the subscriber modem with the pilot tone as reference. The two modems are put on hold to save the characteristic parameters for the momentary data transfer followed by transfer of the ringing signal via the dedicated line to the subscriber modem.

Abstract: A method of resynchronizing data transfer between two modems connected by a dedicated line following a fault caused by a ringing signal, whereby at least one of the modems is assigned to a central office and the other modem is assigned to a remote subscriber, is implemented by setting a ringing ID in the central office modem as soon as a ringing signal is to be sent to the subscriber modem connected via the dedicated line, transferring a ringing alert to the connected subscriber modem, interrupting transmission of the pilot tone accompanying the data transfer set by the central office modem and interrupting clock frequency synchronization implemented during data transfer in the subscriber modem with the pilot tone as reference, signalling the central office modem and subscriber modem on hold to save the characteristic parameters for the momentary data transfer in the two modems followed by transfer of the ringing signal via the dedicated line to the subscriber modem, resetting the ringing ID in the central of