Title: AFC circuit, carrier recovery circuit and receiver device
Application Number: 200410042601 Application Date: 1998.09.18
Publication Number: 1543154 Publication Date: 2004.11.03
Approval Pub. Date: Granted Pub. Date:
International Classifi-cation: H04L27/22,H04N5/455
Applicant(s) Name: Japan Broadcasting Corp. Address:
Inventor(s) Name: Hamazumi Hiroyuki, Hashimoto Akinori
Attorney & Agent: hao qiangfen
Abstract:
     Stabilized carrier recovery is acheived even at the time of a low C/N ratio by measuring the phase of a signal and controlling VCO or NCO (Numerical Controlled Oscillator) using only a period having few constellation points. At this time, false lock phenomenon is avoided as follows. That is, relatively short SYNC modulated by an already-known pattern is entered into a modulation wave, VCO or NCO oscillation frequency is swept in a wide range and sweep is stopped at a frequency in which the SYNC can be received, thereby carrying out coarse control AFC. Further, a period having long to some extent, having few constellation points is provided in the modulation wave and then, a difference between the frequency of a received modulated signal and a local oscillation signal of VCO or NCO is obtained in this period. This frequency difference is analyzed according to the phase differential function method, self-correlation function method or count method, and the VCO or NCO is controlled based on this result of analysis.
Time: 8
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