Abstract: A combined cable/digital subscriber line (DSL) modem and method for data transmission. Upstream data is transmitted to a data communications network through a two wire pair to a central office using unidirectional DSL transmission. Downstream data is transmitted from the data communications network to the combined cable/DSL modem via a cable network using unidirectional cable transmission. Thus, bi-directional data communications is established using two unidirectional transmission links for faster and more efficient data communication.

Abstract: The present invention is generally directed to an xDSL modem that is capable of transmitting at multiple data rates. Specifically, the xDSL modem is configured to generally transmit at a high data rate (typically the highest data rate supported by the line), but will reduce its data transmission rate in response to one or more sensed conditions. In this regard, it has been found that transmitting at a data rate that is low enough to avoid significant corruption, and thus retransmission, achieves a higher overall data transmission rate than that which is achieved if re-transmissions are required. Further, various conditions may be sensed that will prompt the xDSL modem to alter its transmission rate, including detecting an unfiltered POTS device going Off-Hook. In accordance with one aspect of the present invention, at modem startup, the Off-Hook condition and other line problems are detected by direct measurement of the line impedance.