Abstract: A data apparatus (e.g., a modem) continues to generate an analog line signal acceptable to a remote data apparatus' receiver when software fails to deliver samples used to generate the line signal to the hardware in time. The data apparatus uses symbols, rather than samples, which are transmitted from a data-pump unit software to an analog front-end (AFE) unit to generate the analog line signal. When the data-pump is late in providing a new set of symbols, the AFE unit uses previous symbols, randomized versions of previous symbols, or some other source of acceptable symbols to generate a transmit line signal. While data errors will still occur, these data errors are a normal occurrence for data apparatus and a link-layer protocol will detect and retransmit the erred data. The invention avoids having the line signal distorted, which can create data transmission outages due to the remote data apparatus entering into a rate change, initiating a retrain operation, or failing entirely.

Abstract: A split-architecture modem splits the physical layer protocol into a logical operations portion and a signal processing portion. A first processor (e.g., a general purpose processor (GPP)) of the modem performs the logical operations of the physical layer protocol along with the data link layer protocol. A second processor (e.g., a digital signal processor (DSP)) of the modem performs the signal processing portion of the physical layer protocol.

Abstract: The problem of tracking rapid changes in the echo signals associated with modems is eliminated by using an echo canceler consisting of cascaded adaptive filters. Each filter in the structure contributes to the modeling of the overall echo path impulse response, with a longer filter providing the ability to model long echo path impulse responses and a shorter filter providing the ability to track changes in the echo path impulse response over time.

Abstract: The problem of tracking rapid changes in the echo signals associated with modems is eliminated by using an echo canceler consisting of cascaded adaptive filters. Each filter in the structure contributes to the modeling of the overall echo path impulse response, with a longer filter providing the ability to model long echo path impulse responses and a shorter filter providing the ability to track changes in the echo path impulse response over time.