Abstract: A system for providing subscriber line power to an auxiliary device may include a primary communications device, a secondary communications device, and an auxiliary device. The primary communications device and the secondary communications device may be connected to opposite ends of at least one subscriber line. The auxiliary device may be connected to the secondary communications device. The auxiliary device may be powered by the primary communications device via the subscriber line and the secondary communications device. A power capacity metric of the at least one subscriber line may be determined. An operating power metric of the secondary communications device may be determined. A power budget may be calculated from the power capacity metric and the operating power metric. The power budget may be enforced. For example, the secondary communications device may limit power to the auxiliary device to enforce the power budget.

Abstract: A noise cancellation system configured to isolate and process a common mode noise signal to generate a cancellation signal. The cancellation signal is combined with a differential signal to cancel unwanted differential mode noise that coupled onto the differential signal. In one embodiment a multi-channel communication system utilizes two or more channels that are in close proximity to other alien channels. A common mode signal isolation unit is configured to isolate common mode noise. The common mode noise signal is processed with a filter or other means to generate a cancellation signal. The cancellation signal is combined with the differential signal to thereby cancel noise that coupled onto the differential signal. The processed common mode noise signal may be made to approximate the differential mode noise signal. The common mode signal may be obtained from a center tap of a transformer, or a sensing winding of a three winding transformer.