Phase detectors in carrier recovery for offset QAM and VSB

(54) PHASE DETECTORS IN CARRIER

RECOVERY FOR OFFSET QAM AND VSB

(75) Inventors: Thuji S. Lin, Irvine, CA (US);

Tian-Min Liu, Laguna Niguel, CA
(US); Stephen E. Krafft, Los Angeles,
CA (US)

(73) Assignee: Broadcom Corporation, Irvine, CA
(US)

( * ) Notice: This patent issued on a continued prosecution application filed under 37 CFR 1.53(d), and is subject to the twenty year patent term provisions of 35 U.S.C. 154(a)(2).

Subject to any disclaimer, the term of this patent is extended or adjusted under 35 U.S.C. 154(b) by 0 days.

(21) Appl. No.: 09/433,732

(22) Filed: Nov. 3, 1999

Related U.S. Application Data

(60) Provisional application No. 60/107,103, filed on Nov. 4, 1998, provisional application No. 60/107,037, filed on Nov. 3, 1998, provisional application No. 60/106,938, filed on Nov. 3, 1998, provisional application No. 60/106,923, filed on Nov. 3, 1998, provisional application No. 60/106,922, filed on Nov. 3, 1998, and provisional application No. 60/106,921, filed on Nov. 3, 1998.

(51) Int. CI. H03D 3/22

(52) U.S. CI 375/375; 375/327; 375/376;

329/307

(58) Field of Search 375/232, 233,

375/235, 279, 281, 284, 326-327, 329, 332, 344, 345, 346, 375-376; 329/304, 307, 308; 348/725, 726

(56) References Cited

U.S. PATENT DOCUMENTS

4,856,027 A * 8/1989 Nakamura et al 375/327

Improved carrier recovery, symbol timing, and carrier phase tracking systems and methods suitable for use in connection with a dual-mode QAM/VSB receiver system are disclosed. Carrier and phase recovery systems operate on complex signals representing symbols having the same time stamp for each phase error term, in-phase signals are sampled twice a symbol at the in-phase symbol sampling time and at the quadrature-phase symbol sampling time. The signals are de-multiplexed to generate I and X7 data streams, where I represents the in-phase sampling time signals and X7 represents mid-symbol point sample times. A similar procedure is carrier out on quadrature-phase signals. When the in-phase signal is de-multiplexed to generate a symbol I, the quadrature-phase signal is de-multiplexed to generate its mid-symbol point Xe. Both I and Q are decoded in a decision device to define a symbol error term, which is combined with the opposite mid-symbol signal to define a phase error term P7 and PG for each rail. In both cases, the symbol (I) decision (I), and mid-symbol (Xe) in each phase error term (P7) computation will have the same prime index.

8 Claims, 16 Drawing Sheets

U.S. PATENT DOCUMENTS

5,235,424 A 8/1993 Wagner et al 358/174

5,282,023 A 1/1994 Scarpa 358/36

5,311,547 A 5/1994 Wei 375/18

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OTHER PUBLICATIONS

ATSC Standard RF/Transmission Systems, Guide to the Use of the ATSC Digital Standard, pp. 96-101. (Oct. 4, 1995). ATSC Standard, Receiver Characteristics, Guide to the Use of the ATSC Digital Television Standard, pp. 102-136. (Oct. 4, 1995).

* cited by examiner