Block-adaptive equalization using partial decision feedback in digital broadcast communications

• US 6,559,894 B2
• Filed: 06/11/2001
• Issued: 05/06/2003
• Est. Priority Date: 10/21/1999
• Status: Expired due to Term

• Current Assignee: ARRIS Enterprises LLC (CommScope Holding Company, Inc.)
• Original Assignee: Digeo Incorporated (CommScope Holding Company, Inc.)
• Inventors: Henderson, Thomas Ross, Omura, Jimmy Kazuhiro, Peting, Mark Robert, Dabell, Steve
• Primary Examiner(s): Miller, John
• Assistant Examiner(s): Tran, Trang U.
• Application Number:
  US09/879,662
• Publication Number:
  US 20020009135A1
• Time in Patent Office: 694 Days
• Field of Search: H04/N.5217, H04/N.544, 348/611, 348/613, 348/614, 375/229, 375/230, 375/231, 375/232, 375/233, 375/234, 375/235, 375/236
• US Class Current: 348/614
• CPC Class Codes: H04L 1/0059 Convolutional codes
• CPC Class Codes: H04L 1/0071 Use of interleaving interleaving per se H03M13/27
• CPC Class Codes: H04L 2025/03382 Single of vestigal sideband
• CPC Class Codes: H04L 2025/0377 during the reception of training signals
• CPC Class Codes: H04L 25/03133 with a non-recursive structure H04L25/03127 takes precedence

Abstract

A block-adaptive method of performing equalization on a signal received over a broadcast system, includes providing a set of predetermined symbols that correspond to symbols in a data field synchronization segment of a data field having a plurality of segments wherein a data frame having at least two of these data fields is transmitted over the signal in the broadcast system during a block-time interval, correlating complex samples of the signal with the set of predetermined symbols to extract a corresponding impulse response during the block-time interval, selecting a phase identifying the start of the block-time interval from the correlated complex samples, estimating an equalizer filter using the set of predetermined symbols and an initial data field synchronization segment provided at the start of the block-time interval, updating the equalizer filter using subsequent complex samples of the signal to extract a subsequent impulse response and correlate with a reference segment, wherein the reference segment corresponds to either the predetermined symbol sequence or a partial decision feedback segment.

Claims

1. A method of performing equalization on a signal received over a broadcast system, comprising:

providing a set of predetermined symbols that correspond to symbols in a data field synchronization segment of a data field having a plurality of segments wherein a data frame having at least two of these data fields is transmitted over the signal in the broadcast system during a block-time interval;

correlating complex samples of the signal with the set of predetermined symbols to extract a corresponding impulse response during the block-time interval;

selecting a phase identifying the start of the block-time interval from the correlated complex samples;

estimating an equalizer filter using the set of predetermined symbols and an initial data field synchronization segment provided at the start of the block-time interval;

updating the equalizer filter using subsequent complex samples of the signal to extract a subsequent impulse response and correlate with a reference segment, wherein the reference segment corresponds to either the predetermined symbol sequence or a partial decision feedback segment.

2. The method of claim 1, wherein the set of predetermined symbols corresponds to the data field synchronization segment of an ATSC digital television signal system.

3. The method of claim 1, wherein the updating of the equalizer filter occurs continuously once the equalizer is estimated and the signal remains synchronized.

4. The method of claim 1, wherein the partial decision feedback segment used to update the equalizer filter is derived by estimating the sign-bit of symbols being transmitted in the signal.

5. The method of claim 1, wherein the reference segment used to update the equalizer is set to the predetermined symbol sequence when a subsequent data field synchronization segment is transmitted in the subsequent impulse response.

6. The method of claim 1, wherein the reference segment used to update the equalizer is set to the partial decision feedback segment when a subsequent data field synchronization segment is not transmitted in the subsequent impulse response.

7. An apparatus for equalizing a signal received over a broadcast system, comprising:

a predetermined symbol section that stores a set of predetermined symbols corresponding to symbols in a data field synchronization segment of a data field having a plurality of segments wherein a data frame having at least two of these data fields is transmitted over the signal in the broadcast system during a block-time interval;

a partial decision feedback section that estimates the sign-bits for symbols transmitted in the signal;

a complex correlator that correlates complex samples of the signal with the set of predetermined symbols to extract a corresponding impulse response during the block-time interval and determines the phase identifying the start of the block-time interval; and

an estimator that estimates the equalizer using the set of predetermined symbols with an initial data field synchronization provided at the start of the block-time interval and subsequently updates the equalizer using subsequent complex samples of the signal to extract a subsequent impulse response and correlate with reference segment, wherein the reference segment corresponds to either the set of predetermined symbols or a partial decision feedback segment.

8. The apparatus of claim 7, wherein the set of predetermined symbols corresponds to a data field synchronization segment in an ATSC digital television signal system.

9. The apparatus of claim 7, wherein the complex correlator and estimator update the equalizer filter continuously once the equalizer is initialized and the signal remains synchronized.

10. The apparatus of claim 7, wherein the partial decision feedback segment used to update the equalizer filter is derived by estimating the sign-bit of symbols transmitted in the signal.

11. The apparatus of claim 7, wherein the reference segment used to update the equalizer is set to the predetermined symbol sequence when a subsequent data field synchronization segment is transmitted in the subsequent impulse response.

12. The apparatus of claim 7, wherein the reference segment used to update the equalizer is set to the partial decision feedback segment when a subsequent data field synchronization segment is not transmitted in the subsequent impulse response.

13. An apparatus for performing equalization on a signal received over a broadcast system and acquired, comprising:

means for providing a set of predetermined symbols that correspond to symbols in a data field synchronization segment of a data field having a plurality of segments wherein a data frame having at least two of these data fields is transmitted over the signal in the broadcast system during a block-time interval;

means for correlating complex samples of the signal with the set of predetermined symbols to extract a corresponding impulse response during the block-time interval;

means for selecting a phase identifying the start of the block-time interval from the correlated complex samples;

means for estimating an equalizer filter using the set of predetermined symbols and an initial data field synchronization segment provided at the start of the block-time interval;

means for updating the equalizer filter using subsequent complex samples of the signal to extract a subsequent impulse response and correlate with a reference segment, wherein the reference segment corresponds to either the predetermined symbol sequence or a partial decision feedback segment.

14. Apparatus comprising a computer-readable storage medium tangibly embodying program instructions for performing equalization on a signal received over a broadcast system, the program instructions including instructions operable to cause a programmable process to:

provide a set of predetermined symbols that correspond to symbols in a data field synchronization segment of a data field having a plurality of segments wherein a data frame having at least two of these data fields is transmitted over the signal in the broadcast system during a block-time interval;

correlate complex samples of the signal with the set of predetermined symbols to extract a corresponding impulse response during the block-time interval;

select a phase identifying the start of the block-time interval from the correlated complex samples;

estimate an equalizer filter using the set of predetermined symbols and an initial data field synchronization segment provided at the start of the block-time interval;

update the equalizer filter using subsequent complex samples of the signal to extract a subsequent impulse response and correlate with a reference segment, wherein the reference segment corresponds to either the predetermined symbol sequence or a partial decision feedback segment.