Invention Grant
US08259859B2 Method and system for carrier recovery for QAM 失效
QAM载波恢复方法与系统

  • Patent Title: Method and system for carrier recovery for QAM
  • Patent Title (中): QAM载波恢复方法与系统
  • Application No.: US12563850
    Application Date: 2009-09-21
  • Publication No.: US08259859B2
    Publication Date: 2012-09-04
  • Inventor: Honghui Xu
  • Applicant: Honghui Xu
  • Applicant Address: US CA Milpitas
  • Assignee: Techwell LLC
  • Current Assignee: Techwell LLC
  • Current Assignee Address: US CA Milpitas
  • Agency: Fogg & Powers LLC
  • Main IPC: H04L27/00
  • IPC: H04L27/00
Method and system for carrier recovery for QAM
Abstract:
Systems and methods of carrier frequency acquisition or recovery in a receiver. The receiver is able to achieve carrier acquisition when a frequency offset is large (e.g., near a decision boundary). The receiver includes a demodulator, an equalizer, and a carrier recovery module. The carrier recovery module includes a decision device and phase detector, a phase error differentiator, a frequency direction confidence module, and a frequency and phase combiner module. The carrier recovery module calculates a phase error differential between a phase error at a first time and a phase error at a second time. Based on the phase error differential, the frequency direction confidence module generates a frequency offset confidence number. The frequency offset confidence number provides an indication of the direction of a frequency offset and a degree of certainty related to a detected direction (e.g., positive or negative) of the frequency offset. If the confidence number is greater than a threshold value, a joint frequency and phase lock loop (“FPLL”) is used for carrier acquisition. If the confidence number is less than the threshold value, a phase lock loop (“PLL”) is used for carrier acquisition.
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