Conexant Systems, Inc.

Globespan Semiconductor, Inc.

Farooq Jabbar

Ehud Langberg

William H Scholtz

Weimin Liu

A system and method for performing pilot tone based timing recovery in a communication system using the discrete multi-tone (DMT) modulation. In DMT modulation, interference is introduced to the phase of the pilot tone in the transmitter due to the cyclic prefix. Broadly, a receiver is configured to detect and apply a phase offset to the pilot tone in a phase locked-loop upon recognition of far-end signal segments during transceiver initialization. The output of the phase locked-loop is then used to control the timing of the analog-to-digital (A/D) and digital-to-analog (D/A) conversions. In alternative embodiments, the receiver is configured to detect and remove the cyclic prefix from the far-end signal either prior to, or after, time-domain equalization. In a similar manner, the resulting signal stream is applied to the input of the timing recovery phase locked-loop (PLL). The output of the PLL is used to control the timing of the A/D and D/A converters. In a further alternative embodiment, a phase error on the pilot tone is estimated in the frequency domain. The phase error is then applied to the input of a modified timing recovery PLL to reduce phase interference on the pilot tone.

System and method for timing recovery in a discrete multi-tone system

A DSL communication device wherein the state of component coefficients are saved in a memory of a DSL device so that at a later time, the DSL device may initiate a warm start activation sequence wherein the last known channel parameters are used to train the equalizer, significantly reducing the amount of equalizer training required by eliminating the requirement that the aforementioned coefficients be transferred between DSL devices.

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Parlin, NJ, United States of America

Farooq Jabbar