Dual mode QAM/VSB receiver

• US 7,403,579 B2
• Filed: 01/07/2005
• Issued: 07/22/2008
• Est. Priority Date: 11/03/1998
• Status: Expired due to Fees

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Tan, Loke Kun, Jaffe, Steven T., Liu, Tian-Min
• Primary Examiner(s): Tse; Young T.
• Application Number:
  US11/031,107
• Publication Number:
  US 20050105651A1
• Time in Patent Office: 1,292 Days
• Field of Search: 375/233, 375/235, 375/280, 375/281, 375/332, 375326-327, 375/344, 375/371, 375/373, 375/376, 329/304, 329/307, 329/345, 332/103, 327/146, 327/147, 327/155, 327/156
• US Class Current: 375/326
• CPC Class Codes: H04B 1/68 for wholly or partially suppressing the carrier or one side band
• CPC Class Codes: H04L 2025/03382 Single of vestigal sideband
• CPC Class Codes: H04L 2025/0342 QAM
• CPC Class Codes: H04L 2025/0349 as a feedback filter
• CPC Class Codes: H04L 2025/03503 as a combination of feedback and prediction filters
• CPC Class Codes: H04L 2027/0032 at baseband and passband
• CPC Class Codes: H04L 2027/0042 the equaliser providing the offset correction per se
• CPC Class Codes: H04L 2027/0057 quadrature phase
• CPC Class Codes: H04L 2027/0067 Phase error detectors
• CPC Class Codes: H04L 2027/0087 Out-of-band signals, (e.g. pilots)
• CPC Class Codes: H04L 25/03057 with a recursive structure H04L25/03031 takes precedence
• CPC Class Codes: H04L 27/02 Amplitude-modulated carrier systems, e.g. using on-off keying; Single sideband or vestigial sideband modulation H04L27/32 takes precedence
• CPC Class Codes: H04L 27/066 Carrier recovery circuits H04L27/2271 takes precedence
• CPC Class Codes: H04L 27/2273 associated with quadrature demodulation, e.g. Costas loop
• CPC Class Codes: H04L 27/3427 in which the constellation is the n - fold Cartesian product of a single underlying two-dimensional constellation
• CPC Class Codes: H04L 27/3827 in which the carrier is recovered using only the demodulated baseband signals
• CPC Class Codes: H04N 11/24 High-definition television systems
• CPC Class Codes: H04N 21/426 Internal components of the client ; Characteristics thereof H04N5/44 takes precedence
• CPC Class Codes: H04N 21/4382 Demodulation or channel decoding, e.g. QPSK demodulation analog front ends or means for connecting modulators, demodulators or transceivers to a transmission line H04L27/0002
• CPC Class Codes: H04N 5/21 Circuitry for suppressing or minimising disturbance, e.g. moiré or halo
• CPC Class Codes: H04N 5/211 : Ghost signal cancellation H04N23/81 takes precedence
• CPC Class Codes: H04N 5/44 : Receiver circuitry for the reception of television signals according to analogue transmission standards H04N5/14 takes precedence
• CPC Class Codes: H04N 5/46 : for receiving on more than one standard at will deflecting circuits of multi-standard receivers H04N3/27

Abstract

A television receiver system capable of receiving and demodulating television signal information content that has been modulated and transmitted in accordance with a variety of modulation formats is disclosed. In particular, the system is able to accommodate receipt and demodulation of at least 8 and 16-VSB modulated signals in order to support US HDTV applications, as well as 64 and 256-QAM modulated signals, for European and potential US CATV implementations. The system includes carrier and timing recovery loops adapted to operate on an enhanced pilot signal as well as decision directed carrier phase recovery loops. Phase detectors operate on I and Q rail signals, or generate a Q rail from a Hilbert transform of the I rail. Decision directed loops incorporate a trellis decoder in order to operate on sequence estimated decisions for improved reliability in poor SNR environments.

Claims

1. A carrier recovery apparatus, comprising:

a first demultiplexer to generate a sampled first phase symbol and a first phase mid-symbol based on an input signal, wherein the sampled first phase symbol is sampled at a first sampling time and the first phase mid-symbol is sampled at a second sampling time;

a first decision device block to generate a first phase symbol decision based upon the sampled first phase symbol;

a first adder to combine the first phase symbol decision and the sampled first phase symbol to produce a first error term;

a first multiplier to multiply the first error term and a second phase mid-symbol to produce a first phase error term, wherein the second phase mid-symbol is sampled at the first sampling time; and

means for generating a timing reference signal based on the first phase error term.

2. The carrier recovery apparatus of claim 1, wherein the input signal is transmitted on a first carrier frequency and received on a second carrier frequency and the first carrier frequency and the second carrier frequency are offset in frequency and/or phase, further comprising:

a phase splitter configured to receive the input signal, wherein the phase splitter substantially reduces the offset in frequency and/or phase based on the timing reference signal.

3. The carrier recovery apparatus of claim 1, wherein the means for generating the timing reference signal based on the first phase error term comprises:

a loop filter to produce a control voltage based on the first phase error term; and

an oscillator to produce the timing reference signal based upon the control voltage.

4. The carrier recovery apparatus of claim 1, further comprising:

a phase splitter configured to receive the input signal including a first phase symbol and a second phase symbol.

5. The carrier recovery apparatus of claim 4, wherein the first demultiplexer generates the sampled first phase symbol and the first phase mid-symbol based on the first phase symbol.

6. The carrier recovery apparatus of claim 4, further comprising:

a second demultiplexer to generate a sampled second phase symbol and the second phase mid-symbol based on the second phase symbol, wherein the sampled second phase symbol is sampled at the second sampling time and the second phase mid-symbol is sampled at the first sampling time;

a second decision device block to generate a second phase symbol decision based on the sampled second phase symbol;

a second adder to combine the second phase symbol decision and the sampled second phase symbol to produce a second error term; and

a second multiplier to multiply the second error term and the first phase mid-symbol to produce a second phase error term.

7. The carrier recovery apparatus of claim 6, further comprising:

a multiplexer to produce consecutive phase error terms by multiplexing the first phase error term and the second phase error term, wherein the means for generating the timing reference signal generates the timing reference signal based on the consecutive phase error terms.

8. The carrier recovery apparatus of claim 4, wherein the phase splitter samples the first phase symbol at the first sampling time and the second sampling time.

9. The carrier recovery apparatus of claim 4, wherein the first phase symbol is a in-phase symbol and the second phase symbol is a quadrature-phase symbol of an Offset-QAM (OQAM) input signal.