Patent ID: 6700940
Filing Date: 2004-03-02
Classification: H04L

Abstract:
A carrier reproduction circuit for use in a digital broadcasting receiver which receives a digital modulated communication signal comprising a plurality of modulated primary signals and a plurality of modulated burst symbol signals wherein the modulated primary signals are obtained by modulating a digital primary signal with a plurality of modulation methods with respective necessary C/N values being different, and each of the modulated burst symbol signals is obtained by modulating a burst symbol signal having a known-pattern with the modulation method associated with the least necessary C/N value, said carrier reproduction circuit, comprising:reception phase detection means for detecting a reception phase of the demodulated burst symbol signal; and carrier reproduction phase difference detecting means, comprising a phase difference table of absolute phase having one phase convergence point and a phase difference table of the phase rotated from the absolute phase by 180Â° so that any one thereof is selected based on the phase detected by said reception phase detection means, to send out the output based on the phase difference between the phase obtained from the signal point position of said reception signal and the phase convergence point, wherein carrier reproduction is implemented by controlling the frequency of the reproduced carrier so that the phase obtained from said signal point position coincides with the phase convergence point.