Hing Wai Hung

US Patent:

20010022813, Sep 20, 2001

Filed:

Feb 27, 2001

Appl. No.:

09/794724

Inventors:

Loke Tan - Laguna Niguel CA, US
Tian-Min Liu - Laguna Niguel CA, US
Hing Ada Hung - San Juan Capistrano CA, US

Assignee:

Broadcom Corporation

International Classification:

H03H007/30

US Classification:

375/233000

Abstract:

A system for reducing the complexity of an adaptive decision feedback equalizer, for use in connection with a dual-mode QAM/VSB receiver system is disclosed. QAM and VSB symbols, which are expressed in two's compliment notation, include an extra bit required to compensate for a fixed offset term introduced by the two's compliment numbering system. A decision feedback equalizer includes a decision feedback filter section which operates on symbolic decisions represented by a wordlength which excludes the added bit representing the offset. The vestigal word is convolved with the decision feedback filter's coefficients, while a DC component, corresponding to the excluded bit, is convolved with the same coefficient values in a correction filter. The two values are summed to provide an ISI compensation signal at the input of a decision device such as a slicer. A DC component representing a pilot tone in VSB transmission systems also introduces a DC component, and additional bits, to a VSB wordlength. These additional bits are similarly excluded and the vestigal representation convolved with coefficient values in a decision feedback filter. The DC component, including the pilot tone representation, is convolved with the same coefficient values in a correction filter.

US Patent:

20020172276, Nov 21, 2002

Filed:

Jun 27, 2002

Appl. No.:

10/184384

Inventors:

Loke Tan - Laguna Niguel CA, US
Tian-Min Liu - Laguna Niguel CA, US
Hing Ada Hung - San Juan Capistrano CA, US

Assignee:

Broadcom Corporation

International Classification:

H03H007/30
H03K005/159

US Classification:

375/233000

Abstract:

A system for reducing the complexity of an adaptive decision feedback equalizer, for use in connection with a dual-mode QAM/VSB receiver system is disclosed. QAM and VSB symbols, which are expressed in two's compliment notation, include an extra bit required to compensate for a fixed offset term introduced by the two's compliment numbering system. A decision feedback equalizer includes a decision feedback filter section which operates on symbolic decisions represented by a wordlength which excludes the added bit representing the offset. The vestigal word is convolved with the decision feedback filter's coefficients, while a DC component, corresponding to the excluded bit, is convolved with the same coefficient values in a correction filter. The two values are summed to provide an ISI compensation signal at the input of a decision device such as a slicer. A DC component representing a pilot tone in VSB transmission systems also introduces a DC component, and additional bits, to a VSB wordlength. These additional bits are similarly excluded and the vestigal representation convolved with coefficient values in a decision feedback filter. The DC component, including the pilot tone representation, is convolved with the same coefficient values in a correction filter.

US Patent:

20040196897, Oct 7, 2004

Filed:

Apr 23, 2004

Appl. No.:

10/830827

Inventors:

Loke Tan - Laguna Niguel CA, US
Tian-Min Liu - Laguna Niguel CA, US
Hing Ada Hung - San Juan Capistrano CA, US

Assignee:

Broadcom Corporation

International Classification:

H04B001/10
H03K005/159

US Classification:

375/233000, 375/350000, 375/340000

Abstract:

A system for reducing the complexity of an adaptive decision feedback equalizer, for use in connection with a dual-mode QAM/VSB receiver system is disclosed. QAM and VSB symbols, which are expressed in two's compliment notation, include an extra bit required to compensate for a fixed offset term introduced by the two's compliment numbering system. A decision feedback equalizer includes a decision feedback filter section which operates on symbolic decisions represented by a wordlength which excludes the added bit representing the offset. The vestigal word is convolved with the decision feedback filter's coefficients, while a DC component, corresponding to the excluded bit, is convolved with the same coefficient values in a correction filter. The two values are summed to provide an ISI compensation signal at the input of a decision device such as a slicer. A DC component representing a pilot tone in VSB transmission systems also introduces a DC component, and additional bits, to a VSB wordlength. These additional bits are similarly excluded and the vestigal representation convolved with coefficient values in a decision feedback filter. The DC component, including the pilot tone representation, is convolved with the same coefficient values in a correction filter.