Pctel, Inc.

Di Zhou

Chien-Cheng Tung

Thomas Paul

Long Wang

Short pseudo-random (PR) probing sequences that comply with ITU V.90 digital impairment learning (DIL) descriptors provide DIL probing sequences that yield high performance in severe inter-symbol interference (ISI) channels. The short PR sequences do not require the insertion of extra zero symbols to get rid of ISI. Further, a novel receiving structure corrects for propagation of digital impairment common in conventional equalizers for an ISI free receipt of the probing sequences within the strictly time constrained probing sequence. Based on the reliably received signals, general digital impairment mapping tables, digital pads, regular and strange RBS patterns, and different types of PCM codecs (A-law/&mgr;-law) are identified.

Digital impairment learning method and system

A host signal processing (HSP) modem or transceiver includes a transmit buffer and a receive buffer. The transmit buffer stores multiple blocks of information representing a transmit signal, and the receive buffer includes available space for multiple blocks of information representing a receive signal. Each block of information corresponds to its respective signal for an associated period that spans the time between consecutive interrupts for the HSP modem. When the host computer fails to service one or more interrupts, the hardware portion of the HSP modem uses the reserve of information from the transmit buffer to generate the transmit signal and stores one or more blocks of information representing the receive signal in the receive buffer. Accordingly, the HSP mode maintains the connection and data throughput even when the host computer misses interrupts. When the host computer services an interrupt, the modem software determines the number of interrupts missed and then dynamically selects the amount of data to process in an attempt to fill the transmit buffer and empty the receive buffer. The amount of information that the modem software processes in response to a single interrupt can be limited so that the transmit buffer is filled and the receive buffer is emptied over a series of serviced interrupts.

Growing community of inventors

San Jose, CA, United States of America

Di Zhou